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CONTENT
General Preface..................................................................................................................................4 About MESA+, in a nutshell................................................................................................8 MESA+ Strategic Research Orientations....................................................................... 10 Research Groups .............................................................................................................. 15 Commercialization.............................................................................................................. 16 National Networks............................................................................................................. 18 International Networks..................................................................................................... 20 Education............................................................................................................................. 21 Awards, honours and appointments............................................................................... 22 Highlights AAMP - Applied Analysis & Mathematical Physics............................................ 25 BIOS - BIOS Lab-on-a-Chip................................................................................... 26 BPE - Biophysical Engineering........................................................................... 27 CMS - Computational Materials Science........................................................... 28 COPS - Complex Photonic Systems...................................................................... 29 CPM - Catalytic Processes and Materials......................................................... 30 IMS - Inorganic Materials Science.................................................................... 31 IOMS - Integrated Optical MicroSystems............................................................ 32 LPNO - Laser Physics and Nonlinear Optics....................................................... 33 LT - Low Temperature Division........................................................................ 34 LT-CMD - Condensed Matter Physics and Devices............................................... 35 MCS - Mesoscale Chemical Systems................................................................. 36 MNF - Molecular Nanofabrication...................................................................... 37 MTG - Membrane Technology Group.................................................................. 38 MTP - Materials Science and Technology of Polymers................................... 39 NE - NanoElectronics......................................................................................... 40 OS - Optical Sciences........................................................................................ 41 PCF - Physics of Complex Fluids........................................................................ 42 POF - Physics of Fluids......................................................................................... 43 SC - Semiconductor Components.................................................................... 44 SEPA-NST - STePHS / CEPTES....................................................................................... 45 SMCT - Supramolecular Chemistry and Technology.......................................... 46 SSP - Solid State Physics.................................................................................... 47 SSP-PNE - Physical Aspects of Nanoelectronics..................................................... 48 TST - Transducer Science and Technology...................................................... 49 Publications MESA+ Scientific Publications 2007............................................................................... 51 About MESA+ MESA+ Governance Structure......................................................................................... 73 Contact details.................................................................................................................... 74
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P R E FA C E
Just at the beginning‌. Nanotechnology does well in the Netherlands. Looking at the output in high-ranked journals and their citations, our country is at the forefront. Reason for this, no doubt about this, is the national program on nanotechnology NanoNed. This program, headed by our former scientific director David Reinhoudt, is unique for the Netherlands and its midterm review was excellent. Nanotechnology, and thus MESA+, benefits from the possibility to perform research at the forefront with young scientists in well equipped facilities throughout the national program. Last year we finished the drawings of the new NanoLab, 2008 will be the realisation and 2009 the opening of the new laboratory. Not only bricks and steel but also new activities in science are necessary to maintain our international position. A respectable number of research programs are granted and it is great to see that several new collaborations have started and existing ones are being formalized. MESA+ also has to play an important role in the region of Twente. Again a number of new spin-off companies has been realized, which brings the total at 37 high-tech companies since the nineties, keeping our standing on valorisation high. Although numerous programs are still running, it is essential to look to the years to come. Invited by the government, the follow-up of NanoNed is now in preparation as a national nano initiative and for MESA+ this will be a very important research agenda for the future.
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One of the important issues for the years to come is energy-related materials. The possibilities nanotechnology can offer towards new concepts of energy carriers and related subjects look more than promising. It will be an area, like the other MESA+ strategic orientations bio-nano, applied nano-photonics, nano-fluidics, nanoelectronics, and nanofabrication, were we should and will excel. Well, we are only at the beginning of a new episode with novel scientific results, innovative young scientists, dedicated technicians and the advanced NanoLab Twente. Prof. dr. ing. Dave H.A. Blank, Scientific Director of MESA+
INTRODUCTION
Shared initiatives for research and production in nanotechnology Both science and industry benefit from shared initiatives for research and production in nanotechnology bring both science and business forward. The MESA+ research programs are directly related to the national research program NanoNed. In NanoNed the importance of a national facility has been acknowledged, and a major part of the effort and the accompanying budget is dedicated to NanoLab NL. NanoLab NL builds up, maintains and provides a coherent and accessible highlevel, state-of-the-art infrastructure for nanotechnological research and innovation in the Netherlands. NanoLab NL is about national cohesion in infrastructure, access, and tariff structure. MESA+ is proud to be part of the national consortium NanoLab NL. NanoLab, location Twente, is of crucial importance to spin-off companies, existing ones, as well as ones still to emerge. It is the place where young and entrepreneurial people translate knowledge to expertise. Enjoying the vibrant environment, they start up new businesses. Till today, 37 spin-offs have started at MESA+; many more are to be expected in the years to come. University of Twente focuses strongly on, and gives high priority to nanotechnology. In 2007 construction started of CarrĂŠ, offering housing to the majority of the MESA+ research groups and NanoLab, a new and highly modern research facility, both buildings expected to be completed in 2009. With the current research facilities becoming available with the opening of the new lab, the socalled High Tech Factory plan has been developed. High Tech Factory is to provide production facilities to spin-off companies. In November 2006, the Innovation Platform Twente recognized this initiative as a significant contribution to the regional innovation system, and made it part of the Agenda of Twente. In 2007 MESA+ together with the companies Bronkhorst, Demcon, EnablingM3, Encapson, IMS, Lionix, Medimate, Medspray, Micronit, MTF, Nanomi, Ostendum R&D, Phoenix, SmartTip, SolMateS, TSST, UT International Ventures and MESA+ Technology Foundry developed a 9 million euro project to gain knowledge and expertise on production capabilities, eventually leading to production equipment. With the ambition and spirit to form the major league in nanotechnology, and with the support of all MESA+ stakeholders, we are looking forward to a bright future. To the benefit of excellent research and business development! Ir. Miriam Luizink, Technical Commercial Director of MESA+
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P R E FA C E
From the MESA+ Supervisory Board In 2007 MESA+ entered into a new phase of its existence. Under the guidance of its new management the institute continued to be a leading scientific laboratory in nanoscience and nanotechnology. NanoNed underwent an international scientific review. Being NanoNed’s lead contractor, MESA+ got full recognition for its outstanding scientific contributions in nanoscience. A summary of those are compiled in this annual report. In my opinion MESA+ always has been a special R&D institute. Inspired by an entrepreneurial attitude, MESA+ has already for many years been an active stimulator for new business development to implement its ground-breaking R&D findings. Usually creating business is an uphill battle: from promising research results to a product usually is a long road which is paved with hurdles and challenges. As a member of the Supervisory Board, it has been my pleasure to witness and to accompany MESA+’s organizational development. In 2007 the laboratory has progressed with the creation of the High Tech Factory. The High Tech Factory’s aim is to offer a unique piloting facility for entrepreneurial developers. Versatile multi-purpose and dedicated high-tech equipment will be made available for them. The High Tech Factory will lower the barriers for developing a new demonstrator product substantially! For the coming year the Supervisory Board intends to assist MESA+ in deciding what know how areas and business fields will be targeted. The original semiconductor orientation of MESA+ may shift further towards emerging areas like new structured materials and new energy.
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As Supervisory Board, we wish the MESA+ R&D team and their directors all the success, inspiration and wisdom to lead and transform MESA+ during the coming years. Dr. Gert Jan Jongerden Member of the Supervisory Board Managing Director Nuon Helianthos
INTRODUCTION
UCLA professor J. Fraser Stoddart is director of the California NanoSystems Institute (CNSI) and holds UCLA’s Fred Kavli Chair in Nanosystems Sciences. He came to UCLA in 1997 from England’s University of Birmingham, where he had been a professor of organic chemistry since 1990 and had headed the university’s School of Chemistry from 1993. In 2005, he received an honorary doctor of science degree from the University of Birmingham, and, in December 2006, he was the proud recipient of the same honor from the University of Twente in the Netherlands. Stoddart is member of the Scientific
Advisory
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In 2007, he has been named Knight Bachelor
From the Scientific Advisory Board
for services to chemistry and molecular nanotechnology
by
Britain’s
Queen
Elizabeth II.
The rate of technological change in the past half-century has been staggering. Personally, I can reflect how my own life has progressed from one that began on a farm in the lowlands of Scotland in the 1940s and 1950s with horses and carts and without electricity to one where in 2007 we are surrounded by technology in every shape and form that works pretty well for the most part. The dramatic growth in information technology, in the wake of the hardware and software that jointly sustain it, has had a huge impact on our daily lives over the past 25 years. Nanotechnology has given birth to many of these new developments and it augurs well for the future of society. Of the different options on the horizon, molecular electronics could start to make inroads into the commercial marketplace, in conjunction with silicon in a hybrid fashion, possibly in the form of inexpensive memory chips that could be embedded in plastic supports, for example. At present, however, those of us researching in the area of molecular electronics must recognize the need for a lot of fundamental work to be carried out well into the future. In the universities and institutes, this effort will have the virtue also of producing a new generation of scientists and engineers who will bring a fresh perspective to the field of nanotechnology and molecular electronics in particular. The MESA+ Institute for Nanotechnology is a pioneering example of such an institute, where scientists of different disciplines come together in a manner reminiscent of selfassembly and do research together that could not tackled with the same proficiency apart. Teamwork within strategic research orientations opens the minds of researchers in highly productive ways. MESA+ is visible worldwide because of its scientific excellence, as well as its impressive infrastructure. My scientific brother Professor David Reinhoudt has elevated MESA+ to such a high standing internationally that it would be fair to say that it is second to none in the world today. He has set the standards for others, like the California NanoSystems Institute (CNSI), to follow. With such a high bar, I’m looking forward to furthering our collaborations and to entering into vigorous and healthy scientific competition. Prof. J. Fraser Stoddart, Scientific Advisory Board
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Profile MESA+ Institute for Nanotechnology is one of the largest nanotechnology research institutes in the world, delivering competitive and successful high quality research. It uses a unique structure, which unites scientific disciplines, and builds fruitful international cooperation to excel in science and education. MESA+ has created a perfect habitat for start-ups in the micro and nano-industry to establish and to mature. MESA+ is the largest research institute of the University of Twente, having intensive cooperation with various research groups within the university. The institute employs approximately 500 people of which 275 are PhD’s or postdocs. The institute holds 1250 m2 of cleanroom space and state of the art research equipment. MESA+ has an integral turnover of 45 million euro per year of which more than 60% is acquired in competition from external sources (National Science Foundations, European Union, industry etc.). The structure within MESA+ supports and facilitates the researchers and stimulates cooperation actively. MESA+ combines the disciplines of physics, electrical engineering, chemistry and mathematics. Internationally appealing research is achieved through this multidisciplinary approach. It is strengthening its international academic and industrial network by fruitful cooperation programs. MESA+ has been the breeding place for 37 high-tech start-ups to date. A targeted program for cooperation with small and medium-sized enterprises is specially set up for start-ups. MESA+ offers the use of its extensive facilities and cleanroom space under friendly conditions. Start-ups and MESA+ work intensively together to promote transfer of knowledge.
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Field and mission MESA+ focuses on nanotechnology based on its underlying strengths in materials science, microsystem technology, bottom-up chemistry, optics and systems. Its mission is: • to excel in its field of science and technology; • to educate researchers and designers in the field; • to build up fruitful national and international cooperation with industry and fellow institutes, and; • to develop a commercialization strategy.
RESEARCH
Participating faculties/research groups Within MESA+ the following faculties/research groups participate:
Organization schedule MESA+
MESA+ has defined the following indicators for achieving its mission: • scientific papers at the level of Science, Nature, or journals of comparable stature; • 1:1 balance between university funding and externally acquired funds; • sizable spin-off activities. MESA+ is a Research School, designated by the Royal Dutch Academy of Science. Organizational structure and programs The MESA+ research programs, also called Strategic Research Orientations (SRO’s), ensure a strong multidisciplinary activity within the institute. An SRO is a large scientific program in the order of 30-35 full-time researchers, combining high-quality research of at least five groups within the institute into a genuine multidisciplinary program, and providing excellent opportunities for international top-level research. Such an ambitious multidisciplinary program is attractive for external funding. A program director is responsible for the scientific coordination of each SRO. The SRO’s and their program directors should achieve a strong presence and exposure in the scientific world. Within the MESA+ institute 25 research groups participate and combine their strenghts within the following disciplines: • Electrical Engineering, Mathematics and Computer Science (EEMCS) • Sciences and Technology (S&T) • Management and Governance (MG) Research facilities MESA+ NanoLab has extensive laboratory facilities at its disposal, offering a wide spectrum of opportunities for researchers in the Netherlands and abroad: • a 1250 m2 fully equipped cleanroom, with a focus on microsystems technology, nanotechnology, CMOS and materials and process engineering; • a fully equipped central materials analysis laboratory; • a number of specialized laboratories for chemical synthesis and analysis, materials research and analysis, and device charactererization. MESA+ has a strong relationship with industry, both through joint research projects with the larger multinational companies, and through a cooperation policy focused on small and medium- sized enterprises. MESA+ NanoLab plays a central part in these collaborations with industry.
Science & Technology (S&T) • B PE: Biophysical Engineering, prof. dr. V. Subramaniam • CMD: Condensed Matter Physics and Devices, prof. dr. ir. H. Hilgenkamp • CMS: Computational Materials Science, prof. dr. P.J. Kelly • COPS: Complex Photonic Systems, prof. dr. W.L. Vos • CPM: Catalytic Processes and Materials, prof. dr. ir. L. Lefferts • IMS: Inorganic Materials Science, prof. dr. ing. D.H.A. Blank • LPNO: Laser Physics and Nonlinear Optics, prof. dr. K.J. Boller • LT: Low Temperature Division, prof. dr. H. Rogalla • MCS: Mesoscale Chemical Systems: prof. dr. J.G.E. Gardeniers • MnF: Molecular NanoFabrication, prof. dr. ir. J. Huskens • MTG: Membrane Technology Group, prof. dr. ing. M. Wessling • MTP: Materials Science and Technology of Polymers, prof. dr. G.J. Vancso • OS: Optical Sciences, prof. dr. J.L. Herek • PCF: Physics of Complex Fluids, prof. dr. F.G. Mugele • PNE: Physical aspects of NanoElectronics, prof. dr. ir. H.J.W. Zandvliet • POF: Physics of Fluids, prof. dr. D. Lohse • SMCT: SupraMolecular Chemistry and Technology, prof. dr. ir. D.N. Reinhoudt • SSP: Solid State Physics, prof. dr. ir. B. Poelsema Electrical Engineering, Mathematics and Computer Science (EEMCS) • AAMP: Applied Analysis and Mathematical Physics, prof. dr. E.W.C. van Groesen • BIOS: BIOS, the Lab-on-a-Chip group, prof. dr. ir. A. van den Berg • IOMS: Integrated Optical MicroSystems, prof. dr. M. Pollnau • NE: NanoElectronics, dr. R. Jansen • SC: Semiconductor Components, prof. dr. J. Schmitz • TST: Transducers Science and Technology, prof. dr. M.C. Elwenspoek
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School of Management and Governance (MB)/ Behavioural Sciences (BS) • STeHPS Science, Technology, Health and Policy Studies Constructive Technology Assessment, prof. dr. A. Rip • SEPA-NST: Social, Ethical, Philosophical Aspects of NanoScience technology, dr. ir. M. Boon
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Dr. ir. Martin Bennink
BioNanotechnology From a nanotechnological point of view life is nothing more than a subtle interplay of a large number of individual molecules, such as proteins and DNA. Within each cell of the human body, thousands of individual molecules interact with each other, resulting in a number of processes which create the function of the cell and make it into something that we refer to as ‘living’. The SRO Bionanotechnology provides tools that allow the study of these biological systems at the nanoscale, allowing the observation and study of single molecules, providing new insights in how nature is organized and how it realizes the multitude of functionalities that cells present. Besides the scientific interest to understand nature in detail, the acquired knowledge can be directly used in different applications. The detection of molecules in very small quantities is extremely important in the diagnosis of diseases, in environmental control and homeland security. Furthermore understanding biology and the progress of diseases on the molecular level allows the development of new therapy strategies.
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The projects include: • Force spectroscopy studies on biomolecular complexes • Development of polymer nanocontainers for cell function mimicry and drug delivery applications • Nanopore detection of DNA-protein interactions • Atomic force microscopy imaging of molecular aggregates • Creating molecular bionanosensors • Using biomolecules for the creation of nanostructures • Patterning biomolecules on non-bio surfaces Program director: dr. ir. Martin Bennink, phone +31 (0)53 489 5652 m.l.bennink@utwente.nl, www.mesaplus.utwente.nl/bionano
The current MESA+ SRO’s are: • BioNanotechnology • NanoElectronics • NanoFabrication • MesoFluidics • Molecular Photonics • Cell-Stress • NanoFluidics
R E S E A R C H
NanoElectronics The NanoElectronics program’s aim is twofold. The first goal is conducting fundamental research on nanoelectronic devices with a curiosity-driven focus. Novel electronic concepts and/or materials are explored. Combination of different materials and expertise is leading to fascinating new results. The second, and more long-term, goal is the application of those new concepts in devices with superior or complementary characteristics as compared to today’s technology. In our interdisciplinary program we are presently studying hybrid devices composed of different types of materials, such as ferromagnets, complex oxides, semiconductors, organic single-crystals and thin films and molecules. We also pay attention to the integration of nanoelectronic devices with mainstream (silicon) electronics. Dr. ir. Wilfred van der Wiel
The projects include: • Nanoscale spintronic devices based on ferromagnetic oxides • Organic materials for nanoscale spintronic devices • Smart self-assembled monolayers for nanoelectronics • Physical properties of single organic molecules • Smart substrates for nanoelectronic devices • First-principles quantum transport theory • Nanostructured interfaces in complex oxides • Silicon nanowires for electron transport and sensing Program director: dr. ir. Wilfred van der Wiel, phone + 31 (0)53 489 2873 w.g.vanderwiel@utwente.nl, www.mesaplus.utwente.nl/nanoelectronics
NanoFabrication The main aim of the NanoFabrication program is the development of general methods for making nanostructures. The NanoFabrication program is a separate discipline within the nanotechnology field because of its perspective on methodology development of nanostructures rather than the more common focus on final structures. The program has thus a fundamental approach and as such differs also from the nanomanufacturing technologies that deal with the actual application of nanotechnology in production processes. The SRO NanoFabrication focuses on key issues such as surface patterning on multiple length scales, complex structures and materials, and 3D nanofabrication with an emphasis on the integration of top-down and bottom-up methods. The projects include: • Integration of nanoimprint lithography and blockcopolymer assembly • Integration of edge lithography and self-assembly • Monolayer fabrication and patterning on complex oxides • Polymeric nanostructures of fluorescent nanoparticles • Porous stamp materials for microcontact printing Program director: prof. dr. ir. Jurriaan Huskens, phone +31 (0)53 489 2537 j.huskens@utwente.nl, www.mesaplus.utwente.nl/nanofabrication
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M E S A + S trate g i c R esearc h O r i entat i ons Prof. dr. Han Gardeniers
MesoFluidics The goal of this program is to study physics and chemistry of and in fluids at the mesoscopic scale. The behaviour and control of fluids, including miscible and immiscible liquids, gases and two-phase gas-liquid systems and of the chemical species contained in these fluids will be studied in a confined environment and more specifically, near plain, nanostructured and/or reactive surfaces and interfaces. Particular focus will be on microfluidic elements that contain materials fabricated by nanotechnology, to which electronically controlled stimuli will be applied in order to control the course of chemical reactions and fluidic behaviour.
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The projects include: • Pressure and shear driven liquid chromatography in microstructured columns with integrated injection and detection elements and microstructures for coupling to e.g. mass spectrometry • Parallel microreactor structures with on-line spectroscopic features (NMR, UV-Vis) for the study of the kinetics of catalytic and enzymatic reactions • Electrowetting and ultrasonic control of fluidic and chemical behaviour • Mass and heat transport in confined systems • Liquid behaviour on nanopatterned and hydrophobic surfaces in microstructures • Catalytic gas sensors • Micro-plasma reactors Program director: prof. dr. Han Gardeniers, phone +31 (0)53 489 4356, j.g.e.gardeniers@utwente.nl, www.mesaplus.utwente.nl/mesofluidics
RESEARCH
Molecular Photonics The strategic potential program in Molecular Photonics focuses on platforms, tools, and (bio)molecules that can be used to design, build, and investigate molecular photonic assemblies. Projects within this program involve synthesis of innovative photonic materials (responsive quantum dot systems, fluorescent self-assembled monolayers, proteins) and the optical creation and interrogation of these assemblies. A newly developed technology platform combining atomic force and optical microscopy with single molecule resolution (the atomic force fluorescence microscope – AFFM) is used to explore the limits of dip-pen nanolithography for patterning and investigating molecular assemblies such as dendrimers and fluorescent proteins on molecular printboards. The projects bridge physics and chemistry expertise within MESA+. The projects include: • Engineering optical emission of quantum dots in polymeric nano- and microspheres • Dip-pen nanolithography for biomolecular assembly
Prof. dr. Jennifer Herek
Program director: prof. dr. Jennifer Herek, phone +31 (0)53 489 3172 j.l.herek@utwente.nl, www.mesaplus.utwente.nl/molecularphotonics
Cell-Stress In many processes taking place in living cells, mechanical properties play a vital role. Cells divide, grow, translocate and adapt their shape to external circumstances: all processes which require an active mechanical behaviour. Conversely, cells also sense external mechanical stress, and respond to it. This can be a direct mechanical response (like stiffening or softening), which can be local or global. Indirect biochemical responses, like a downregulation of receptor molecules or the expression of proteins, can also change the mechanical behaviour. Importantly, also diseases can lead to mechanical alterations. This makes cell mechanics and mechanotransduction a fascinating research area, in which many behaviours are still to be discovered, explained, and potentially used to diagnose the cell (e.g. using the cell’s mechanics as a disease marker). The SRO Cell-Stress aims to analyze and characterize the response of single cells upon mechanical stimulation. By performing this in a microfluidic environment it can potentially generate new diagnosis methods. The projects include: • Biological response of endothelial cells to fluid shear stress • Mechanical response of single living cells to fluid flow in microchannels • Rheology of the cell interior, measured via particle tracking • Cell rheology measured via atomic force microscopy Program director: dr. Michèl Duits, phone +31 (0)53 489 3097 m.h.g.duits@utwente.nl, www.mesaplus.utwente.nl/cellstress
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Dr. Michèl Duits
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Nanofluidics highlight Context
Micro- and Nanofluidics are strongly growing fields with great potential for various applications in technology, chemical industry, diagnostics, and medicine. Through the rapid progress in the miniaturization of structures it is now possible to build microchannels, micropumps, or micromixers for applications in micro- and even nanofluidics. However, many fundamental questions are still unresolved. The aim of the program is to undertake a joint effort to solve some of these questions. More specifically, we aim at a better understanding of the basic properties of the liquid structure at solid surfaces, in both static and dynamic cases. At these interfaces phase separation seems to play a central role, with enormous consequences on the fluid flow boundary conditions (slip versus no-slip). The understanding must be on a level that it can be used to design fluidic micro- and nanosystems where the interaction of the liquid with walls is dominant for the function.
Participants of the SRO Nanofluidics Prof. dr. Detlef Lohse (programme leader) Physics of Fluids (PoF) Prof. dr. ir. Albert van den Berg BIOS Lab-on-a-Chip (BIOS) Prof. dr. Miko Elwenspoek Transducer Science and Technology (TST) Prof. dr. Frieder Mugele Physics of Complex Fluids (PCF) Prof. dr. Andrea Prosperetti Berkhoff-Chair, Physics of Fluids (PoF) Prof. dr. ing. Matthias Wessling Membrane Technology Group (MTG)
The long term goal of the project is to better manipulate and optimize the surface properties of microfluidic devices, to come to better micropumps, micromixtures, and microchannels. The knowledge generated in this multidisciplinary collaboration will thus eventually have an impact on commercial microfluidic devices.
Examples for collaborations
In a collaboration between the Physics of Fluids group and the Membrane Technology Group, the micro-structured material, which can show superhydrophobic behavior with effective contact angles of 160o and beyond (“Lotus effect”), was analysed. Such material is already used for medical applications, microelectromechanics, coatings, buildings, cars, textile, etc. and it will find many more applications in the future. However, under certain conditions the superhydrophobicity can break down: fluid enters into the microstructure and spreads, resulting into the much smaller contact angle of the unstructured material. We observed such a spontaneous transition from the so-called Cassie-Baxter (superhydrophobic) state to the so-called Wenzel (wetted) state: the liquid spreads through the posts in a steplike manner: entering a new row perpendicular to the direction of front propagation takes ms, whereas once this has happened, the row itself is filled on a much faster timescale (“zipping”). In this way squared-shaped or hexagon-shaped propagating wetting patterns emerge, see figure 1.
Figure 1: Bottom views of the front evolution of the transition from a drop on a superhydrophobic surface in the Cassie-Baxter state to the Wenzel state, see sketch (a). In (b) three snapshots for the case with a = 5μm are shown, leading to square-shaped wetted area (see also movie 2). In (c) it is a = 11μm, resulting in a circular wetted area. Figures (d) and (e) show the results of the corresponding numerical simulations with the Lattice-Boltzmann method with a = 5μm and 11μm, respectively.
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highlights of joint Publication [1] Albert van den Berg and Matthias Wessling, Nanofluidics - Silicon for the perfect membrane (News and Views), Nature, 445, 726 (2007). [2] Mauro Sbragaglia, Christophe Pirat, Bram Borkent, Alisia Peters, Rob Lammertink,Matthias Wessling, and Detlef Lohse, Spontaneous breakdown of superhydropbobicity, Phys. Rev. Lett., 99, 156001 (2007). [3] Helmut Rathgen, Kazuyasu Sugiyama, Claus-Dieter Ohl, Detlef Lohse, and Frieder Mugele, Nanometer-resolved collective micromenisci oscillations through diffractive optics, Phys. Rev. Lett., 99, 214501 (2007). [4] Koen van Delft, Jan Eijkel, Dragana Mijatovic, Tamara Druzhinina, Helmut Rathgen, Niels Tas, Albert van den Berg, and Frieder Mugele, Micromachined Fabry-Perot interferometer with embedded nanochannels for nanoscale fluid dynamics, Nano Letters, 7, 345 (2007).
RESEARCH GROUPS
R esearc h Gro u ps
Laser Physics & Nonlinear Optics group The group was founded in 1969 in the early years of the University of Twente and pioneered research on high power gas lasers, such as CO2 and excimer lasers, at that time a rather unexplored field of physics. In the mid-eighties, the group extended its research programme with free-electron lasers. With the appointment of prof.dr. K.J. Boller as the new chair in 2000, the name of the group changed into Laser Physics and Nonlinear Optics to reflect the change in focus towards solid state lasers and nonlinear optics. At the end of 2005, prof.dr. F. Bijkerk was appointed as part-time co-chair for research on XUV Sources and Optics, such as multilayered reflective mirrors for high power Soft X-ray and Ultraviolet (XUV) radiation. In 2007 the group became a member of the MESA+ Institute for Nanotechnology. The mission of the group can be described as exploring the physics and technology of nonlinear optical processes, also in search of applications. This includes a wide range of light intensities and time scales, research on novel or improved light sources, and it includes the selection and control of suitable nonlinear media and advanced optical components. The research currently covers three main themes, nonlinear optical processes for wavelength shifted radiation, extreme nonlinear optics, and the nonlinear interaction of light with free electrons. Prof. dr. Klaus Boller
Mesoscale Chemical Systems Since the beginning of 2007 Prof. Han Gardeniers is leading the Mesoscale Chemical Systems group within the MESA+ Institute for Nanotechnology. The aim of the research group Mesoscale Chemical Systems is to study the behaviour and control of fluids, including miscible and immiscible liquids, gases and two-phase gas-liquid systems and of the chemical species contained in these fluids in a confined environment and more specifically, near plain, nanostructured and/or or reactive surfaces and interfaces. The main research themes are: • “ Exciting” chemistry in microreactors, focusing on microfluidic systems to which electronically controlled stimuli are applied in order to control the course of chemical reactions • Microfluidic process analytical technology (μPAT), focusing on integrated chromatography-based separation methods (a longstanding collaboration with the Vrije Universite it van Brussel) and integrated spectroscopic techniques, like MS and NMR (a collaboration with Radboud Universiteit Nijmegen) • Catalytic microdevices and nanostructures
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The group is a very active user of the NanoLab clean room facilities, collaborates with many of the groups participating in MESA+ and IMPACT, and has a strong organizational link with the CPM group at MESA+ and the University of Twente. Prof. dr. Han Gardeniers
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C ommerc i a l i z at i on
High Tech Factory In 2007 realization of the High Tech Factory, in our former annual report called ‘MST Fabriek’, came a lot closer. High Tech Factory is a shared production facility for products based on micro- and nanotechnology. With the opening of the new NanoLab facilities in 2009, the current MESA+ R&D facilities will become available. Therefore a plan has been developed for a High Tech Factory, providing (pilot scale) production facilities to spin-off companies. In November 2006, the Innovation Platform Twente recognized this initiative as a significant contribution to the regional innovation system, and made it part of the Agenda of Twente. In 2007 the MESA+ Technology Foundry together with the companies Bronkhorst, Demcon, EnablingM3, Encapson, IMS, Lionix, Medimate, Medspray, Micronit, MTF, Nanomi, Ostendum R&D, Phoenix, SmartTip, SolMateS, TSST, UT International Ventures and MESA+ developed a proposal and applied for a grant in ‘Pieken in de Delta’ which has been approved in Q1 2008. The participating companies develop knowledge and expertise on production capabilities, eventually leading to production equipment. The project involves an investment of 4.5 million euro of the project partners and 4.5 million euro of the province of Overijssel and the Ministry of Economic Affairs.
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SolMates In June 2007 SolMates, the 35th spin-off company of MESA+, was launched officially. SolMateS is a research company specialized in functional thin films and coatings, offering high-tech know-how, competences and expertise to innovative industrial partners. SolMates was founded by Joska Broekmaat, Matthijn Dekkers, Arjen Janssens and Paul te Riele.
COMMERCIALIZATION
MESA+ International Ventures The mission of MESA+ International Ventures, a public private partnership, is to transform knowledge into economic good by exploiting and strengthening MESA+ technology platforms. Together with MESA+ research groups, MESA+ International Ventures is constantly scouting and screening newly developed technologies for market potential. In case a technology screens favourable, a next step in the commercialization process is embarked on. This involves researching markets for the specific technology in more detail, contacting potential customers, developing technology towards a demonstrator product and securing necessary Intellectual Property Rights. By so doing, a spin-out company is prepared for which MESA+ International Ventures will attract necessary finance.
Dr. mr. Paul Nederkoorn
Examples of promising technologies include a coating for LEDs to significantly increase light out-coupling and an instantaneous, optionally in-line, optical detection technology for micro-organisms. MESA+ International Ventures is financed by a group of private investors - who also bring in a relevant network for instance for future spin-out finance -, the province of Overijssel and the University of Twente. MESA+ International Ventures is managed by dr. mr. Paul Nederkoorn.
Nano4Vitality Innovation Program The application areas of food and health form a challenging area for innovation. The cost of health care, food safety, the ageing population and many other issues demand an increased innovation rate. The nanometer scale is the relevant scale for processes in living systems. With nanotechnology it is possible, for the first time, to interact with these natural systems on their own scale based on nature’s own principles. Together with the universities of Wageningen, Nijmegen and Groningen, MESA+ created a novel innovation program for health and food applications based on nanotechnology, called Nano4Vitality. The program received a grant of six million euro in 2007 from the Ministry of Economic Affairs and the Province of Overijssel. Projects will be carried out by consortia of industry, high tech SME’s, high tech start-ups and universities, focusing at product or proto type realization in a time frame of three years, based on underlying business cases.
Kennispark Twente Commercialization of nanotechnology research is one of the very strong drivers of MESA+. As illustrated in the topics above, key aspects of the MESA+ agenda encompass business development, facility sharing, area development, and growth towards a production facility. With these key commercialization projects MESA+ contributes strongly to the Kennispark agenda and the provincial and regional innovation systems.
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N at i ona l N et w or k s
NanoNed MESA+ is partner in NanoNed. NanoNed is a national nanotechnology R&D initiative that combines the Dutch strengths in nanoscience and technology in a national network with scientifically, economically and socially relevant research and infrastructure projects. The total budget amounts to 235 Mâ‚Ź and the program runs until 2009. NanoNed is executed by a consortium of nine partners being the main nanotechnology institutes of the Netherlands. Their individual role within the projects and infrastructure investments is defined through proven expertise, specialization and focus combined with strategic vision and ambition. All partners are devoted to developing strong cooperation on the subject of nanotechnology in its different application areas. The program is organized in eleven large interdependent programs called Flagships, based on national R&D strengths and industrial relevance. Several partners are working in each Flagship program under the leadership of an independent scientist. The partnership covers about 200 research projects, which over five years represent more than 1200 years of research. Generic, technology-oriented Flagships run together with more application-oriented programs, to create a cohesive nationwide multidisciplinary program. Additionally, a Technology Assessment program is an integrated part of NanoNed. The assessment will result in a mapping of the societal impact of nanotechnology in close collaboration with the scientists involved.
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To maintain this strong bases in nanotechnology after 2010, NanoNed and its partners, the Technology Foundation STW and the Foundation for Fundamental Research on Matter FOM, have been asked by the Dutch Cabinet to prepare a broad Strategic Research Agenda for nanotechnology in the Netherlands. This in order to keep the Netherlands a competitive nation in the rest of the world. To this end, in the fall of 2007 several thematic workshops with a large group of scientists from universities, knowledge institutes, industry, and experts from governmental and non-governmental organisations have been held. The partners aim to present a Strategic Research Agenda to the Dutch Cabinet in the first half 2008, in order to allow a timely start of the Netherlands Nano Initiative in 2009. MESA+ is strongly involved in this process.
NanoNed partners
N E T W O R K S
NanoLab NL
Impression of the new MESA+ NanoLab
NanoLab NL is a national investment program of high-level, state-of-the-art nanotechnology infrastructure that is accessible to NanoNed and the Dutch research community as a whole. In NanoNed the importance of a national facility has been acknowledged, and a major part of the effort and the accompanying budget is dedicated to NanoLab NL. NanoLab NL builds up, maintains and provides a coherent and accessible high-level, state-of-the-art infrastructure for nanotechnological research and innovation in the Netherlands. NanoLab NL is about national cohesion in infrastructure, access, and tariff structure. 85 M€ of the total NanoNed budget is reserved for NanoLab NL. The partners in NanoLab NL are: • MESA+ at University of Twente • Kavli Institute of Nanoscience at Delft University of Technology • Zernike Institute for Advanced Materials at Groningen University • TNO Science & Industry, Delft, and • Philips Research Laboratories, Eindhoven, as an associate partner Together, these five locations cover most of the country and offer the widest possible spectrum of nanotechnology facilities for researchers in the Netherlands to use. The University Twente, re-allocating the buildings for research and education, is building a new cleanroom and analysis facility, MESA+ NanoLab. The new NanoLab contains 1000 m2 cleanroom and 800 m2 laboratory space. With the investment in NanoLab the university shows the interest for and the importance of Nanotechnology research. In 2007 the Province of Overijssel contributed 1 million euros for the NanoLab building as the facility is of main importance to new and existing spin-off companies. MESA+ NanoLab is scheduled to be ready by spring 2009. In 2007 MESA+ NanoLab started its monthly technical colloquia, aiming to convey expertise and know how of the various equipment and technology within NanoLab in informal discussions. The colloquia have been received very well, and are visited by about 40 to 50 participants.
Symbolic handing over of the first stone of the new MESA+ NanoLab by Carry Abbenhues (Deputy Economic Affairs Province of Overijssel) to Dr. Anne Flierman (University Board)
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Internat i ona l net w or k s
Nanoforumeula researchers
Nanoforumeula Nanoforumeula For Nanonetworking Europe And Latin America This Specific Support Action Nanoforum EU Latin America is funded by the European Union under the Sixth EU Framework Programme for Research and Technological Development; Nanotechnologies and Nanosciences, Knowledge Based Multifunctional Materials and New Production Processes and Devices (FP6, NMP). The project aims to foster lasting research relations between European research organisations and research organisations in Latin America specialising in nanotechnology. Nanoforumeula subsidises exchange visits for some twenty Latin American researchers to four European research organisations specialising in nanotechnology and is organising two workshops and subsequent fact finding missions in Mexico and Brazil enabling European researchers and industrialists to identify opportunities for establishing working relations. Visit the website of Nanoforumeula for more information: www.nanoforumeula.eu.
Frontiers Frontiers is a European Commission Network of Excellence supported by the Sixth Framework Program (FP6) with a focus on the synergies between nanotechnology and the life sciences. The consortium, coordinated by MESA+, leverages the existing strengths and potentials of several key nanotechnology groups in Europe and was kicked-off in August 2004.
Frontiers partners MESA+, University of Twente (NL) iNano, University of Aarhus (DK)
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The year 2007 included several events such as the winterschool in Zermatt, the research meeting in Toulouse and several workshops intended to facilitate the process of integration of consortium partners, in keeping with the spirit of the Networks of Excellence in FP6. The third reporting period was successfully evaluated in October 2007, and was highlighted by the continuation of numerous joint research collaborations. Integration of communication activities was initiated in this period and will be continued in the final period. We are now in the process of formalizing a vehicle to continue the cooperative interactions established by the network.
Chalmers University of Technology (SE) CEMES (FR) Westfalian Wilhelms University (DE) Max Planck Institute for Solid State Physics (DE) University of Cambridge (UK) Forschungszentrum Karlsruhe (DE) IMEC (BE) NCCR (CH) CeNTech (DE)
The coordinator of Frontiers is prof. dr. Vinod Subramaniam. The program manager is dr. Rolf Vermeij. Monique Snippers provides management support and is in charge of network and external communications activities. For further information you can contact dr. Rolf Vermeij, phone +31 (0)53 489 2331, info@frontiers-eu.org, www.frontiers-eu.org.
E D U C A T I O N
E D U C AT I O N Master of Science Program Nanotechnology General information Different researchers and professors from MESA+ active in the fields of Applied Physics, Chemical Engineering and Electrical Engineering joined in to close the gap between scientific and technological progress and conventional disciplinary educational programs by setting up an interdisciplinary Master Program in Nanotechnology. The objective is to provide an educational program for master students as a preparation for a PhD project in nanotechnology. The Master will provide the student with training in the enabling technologies and key aspects relevant for the field of nanotechnology. Furthermore the student will learn to operate in a research environment, to set up, manage and perform research projects, including reporting and communicating the results. The philosophy in setting up the Master is that nanotechnologists must be able to combine expertise and know how, from the different disciplines (nanochemistry, nanobio, nanoengineering and nanophysics). Program Structure This 2-year Master program (120 EC) is divided into 4 semesters. In the first year, seven nanotechnology modules are offered that cover the different subfields in nanotechnology. After this in the second semester two different practical training modules are provided. The first practical training is an intensive course in the MESA+ cleanroom and the second is a larger practical course done in the lab of one of the nanotechnology research groups. The curriculum is further extended with a course focused on improving skills related to searching literature, presenting results in front of an audience and writing a scientific report. And in the last part of the first year the modules “Societal embedding of Nanotechnology” and “Technology venturing” will provide tools for the students to think and to deal with the development of technology in a societal context. Another 15 ec is reserved for elective courses which can be taken to specialize in a particular topic (mostly related to the final thesis assignment). In the second year, an industrial training in a company, involved in nanotechnology research is scheduled and the last 6 to 7 months are reserved for the final master research project which is to done in one of the research groups in nanotechnology. In this project the student will use all his acquired skills to set-up, manage and perform a complete research project. For further information and application for the (international) master program Nanotechnology you can visit the websites: http://nt.graduate.utwente.nl/ or http://www.tnw.utwente.nl/nt or contact the program coordinator: dr. ir. M.L. Bennink, phone +31 (0)53 489 5652, m.l.bennink@utwente.nl.
Fundamentals of Nanotechnology course Nanotechnology is multidisciplinary, and requires expertises from the field of electrical engineering, applied physics, chemical technology and life sciences. The course Fundamentals of Nanotechnology MESA+ is organizing every year provides a first introduction with the complete scope of what nanotechnology is about. The workshop is set up for graduate students and postdoctoral fellows with a training in electrical engineering, applied physics, chemical engineering or any other applied science and who are starting to work or are currently working in the field of nanotechnology. The workshop will be given in a intensive one-week format, in which the participants will attend lectures of different speakers that are active in the nanotechnology research area.
Program Structure Master NT
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Awards , h ono u rs and appo i ntments VIDI awards The Netherlands Organization for Research (NWO) granted VIDI awards to two young excellent MESA+ researchers, Dr. Alexander Brinkman and Dr. Allard Mosk. This award gives researchers the opportunity to develop themselves and their own innovative lines of research in a period of 5 years to appoint one or more researchers. The maximum grant is € 600,000,-. Dr. Alexander Brinkman (Low Temperature division) will investigate the possibilities for teleportation on a chip. Dr. Allard Mosk (COPS) will study and develop new methods to focus light deep inside strongly scattering materials in his project ‘Bringing light to hidden objects in turbid materials’. This will lead to new physical insights on light propagation in such materials, and to new possibilities for phototherapy and optical imaging in non-transparent tissue.
Dr. Alexander Brinkman
VENI award Dr. Pascal Jonkheijm of the Molecular Nanofabrication group received a VENI award of the Netherlands Organization for Research (NWO) for his research on molecular nanoscale cell manipulation. This VENI grant offers Jonkheijm the opportunity to develop his ideas over a further 3 years. The amount of the grant is € 208,000. Golden Medal of the Royal Netherlands Chemical Society Prof. Jurriaan Huskens of the Molecular NanoFabrication group and Program Director of the Strategic Research Orientation NanoFabrication of the MESA+ Institute for Nanotechnology received the 2007 Gold Medal of the Royal Netherlands Chemical Society (KNCV). The KNCV annually awards the Gold Medal to the most promising young chemical researcher in the Netherlands.
Dr. Allard Mosk
Else Kooi prize 2007 The Else Kooi prize 2007, for application-orientated research in the field of semiconductors and chip design, has been awarded to Dr. Wico Hopman for his research on light flow characterization and manipulation in 1 and 2 dimensional photonic crystals. Dr. Hopman is a former PhD of the Integrated Optical Microsystems Group. Overijssel PhD award During the celebration of the 46th Dies Natalis of the University of Twente the Overijssel PhD award of € 5,000.- was handed out to Dr. Christian Nijhuis for his PhD research at the Supramolecular Chemistry & Technology group. His research focuses on molecular electronics. Dr. Nijhuis, who received a Rubicon grant in 2006, currently has a postdoc position at Harvard University.
Prof. Jurriaan Huskens (left)
Rubicon grant The Rubicon program of the Netherlands Organization for Scientific Research (NWO) is directed to promising young postdoctoral researchers who are at the start of their career. This grant gives the laureates the chance to enhance their career prospects by spending up to two years at a top research institution outside the Netherlands. In 2007 Dr. Monique Roerdink of the Materials Science and Technology of Polymers group received a Rubicon grant. This grant allows Dr. Roerdink to do research at the University of Toronto in Canada on polymers for biomedical applications. Her project focuses on studies of release mechanisms of polymer capsule shells and biomedical applications for controlled release at specific tumor locations. Dr. Dorota Rozkiewic of the Supramolecular Chemistry and Technology group received a Rubicon scholarship from NWO.
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Dr. Wico Hopman
University of Twente Education Award During the opening of the Academic Year the award for the best educator of the University of Twente was granted to Prof. Hans Hilgenkamp of the Condensed Matter Physics and Devices group. The award is assigned annually by a student jury of the University of Twente.
Prof. Hans Hilgenkamp
A W A R D S
Silver Herring Prof. dr. ing. Dave Blank, scientific director of MESA+, received the ‘Silver Herring’ for his strong contribution to the innovative and entrepreneurial image of the region of Twente with MESA+ as a leading research institute in the field of nanotechnology. The ‘Silver Herring’ is awarded annually to people who make an important contribution to the region Twente. NanoNed Valorisation Grants The NanoNed Valorisation Grant is an initiative of NanoNed and Technology Foundation STW to fund the creation of new high-tech enterprises emerging from knowledge and expertise developed within the NanoNed Program. Two MESA+ researchers received NanoNed Valorisation Grants in 2007.
Prof. Dave Blank (right)
Dr. Regina Luttge
Dr. Regina Luttge of the Mesoscale Chemical Systems group received a second phase Valorisation Grant of € 200,000.-. With this grant she will establish the start-up company MyLife Technologies which will develop microneedle-integrated patches. Ir. Eric Staijen of the BIOS Lab-on-a-chip group starts a spin-off company that helps veterinarian and cattle farmers to monitor cows who possibly suffer from milk fever. A microfluidic chip based on capillary electrophoresis monitors different species in blood. The first phase Valorisation Grant of € 25,000.- gives him the possibility to perform a technological and economic feasibility study. Honorary Doctorate from the University of Parma Prof. dr. ir. David Reinhoudt of the Supramolecular Chemistry & Technology group and former scientific director of MESA+ received an Honorary Doctorate of the Universitá degli Studi di Parma in Italy. Prof. Reinhoudt is praised internationally because of his contribution to the supramolecular chemistry and nanotechnology. For the same reason the University of Twente awarded him with a ‘Medal of Honour of the University of Twente’ on the occasion of his emeritaat on 13 September 2007. Cum laude distinction In 2007 two MESA+ PhD students received cum laude distinctions for their work. Dr. Floor Wolbers of the BIOS Lab-on-a-chip group finished her PhD thesis ‘Apoptosis chip for drug screening’ with honours. Dr. Dorota Rozkiewic of the Supramolecular Chemistry and Technology group received a cum laude distinction for her thesis ‘Covalent Microcontact Printing of Biomolecules’. Drs. Jealemy Galindo Millan of the Supramolecular Chemistry and Technology group finished her master thesis with honours and also won the Unilever Research Prize for her work. Royal visit During the state visit of president Horst Kohler of the German federal republic to the Netherlands, Queen Beatrix and Horst Kohler visited the University of Twente on 10 October 2007. After talking about economic collaboration in the Euregio, Queen Beatrix visited some projects. Miriam Luizink, technical commercial director of MESA+, presented the institute emphasizing the strenghts of MESA+ with its excellent research position, the presence of state-of-the-art cleanroom- and lab facilities, a strong focus on commercialization and interaction with companies. To illustrate this products of two MESA+ spin off companies were shown, the Medimate Point of Care portable analyzer and the Medspray medical inhalers.
Prof. David Reinhoudt
Queen Beatrix and ir. Miriam Luizink
MESA+ meeting 2007 MESA+ Institute for Nanotechnology organizes the annual MESA+ meeting. The various projects and programs of MESA+ are illustrated by means of lectures and scientific poster presentations. In 2007 the poster with the title ‘Hybrid magnetometers base don YBCO ring flux concentrator’ of Kristiaan Kuit c.s. (Low Temperature Division / Condensed Matter Physics and Devices) won the 1st prize. Appointment of Prof. Stefan Kuhlmann In October 2007 Stefan Kuhlmann is appointed professor at the department of STeHPS (Science, Technology, Health and Policy Studies (STeHPS). The STeHPS group cooperates with the Department of Philosophy (Dr. Mieke Boon) on Technology Assessment of nanotechnology within MESA+.
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Prof. Stefan Kuhlmann
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H I G H L I G H T S
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A P P L I E D A N A LY S I S & M AT H E M AT I C A L P H Y S I C S Hybrid analytical / numerical coupled mode theory The group Applied Analysis & Mathematical Physics conducts research and teaching activities in ordinary and partial differential equations, and in mathematical modeling of problems from the physical and technical sciences. Methods from nonlinear analysis (variational methods, bifurcation theory, dynamical system theory), small scale numerical calculations, and computer-algebra are the main mathematical tools used to study partial differential equations from a series of different areas of applications. The group contributes to MESA+ in the field of theoretical optics, with a focus on phenomena related to the light propagation in nonhomogeneous linear and nonlinear dielectric media. The Maxwell equations of classical electrodynamics are to be solved for structures and devices from guided wave (integrated) optics or, more general, photonics. Computational tools are indispensable for concrete design tasks as well as for more fundamental investigations in photonics. Difficulties arise from the usually very limited range of applicability of purely analytical models, and from the frequently prohibitive effort required for rigorous numerical simulations of practical structures in 3-D. Hence we pursue an intermediate strategy. For specific classes of devices there exist relatively clear physical ideas about the optical behaviour, such that field templates can be written down which cover the major features of the light propagation. The templates are expressed in terms of certain known basis fields of lower dimension, which are computable with much smaller effort. Typically these are guided modes supported by the local optical channels of the device. What then remains is to determine the parameters (functions) in the field template, i.e. to quantify the interactions between the basis fields. Here we use numerical techniques: upon discretization of the amplitude functions by 1D finite elements (FE), variational procedures are applied to reduce the problems to systems of linear equations of small to moderate size. Building on the physical/engineering notions underlying the field templates, and on the tools necessary to compute the basis fields, the FE/variational procedures can be implemented in a flexible, device independent way. Although restricted to configurations where these prerequisites are available, this Hybrid analytical / numerical variant of Coupled Mode Theory (HCMT) still constitutes a tool of some generality for accurate quantitative ab-initio simulations of real-world photonic devices. ďż˝ Figure 1: 2-D propagation of optical waves through a crossing of two high-contrast dielectric waveguides. The plots compare snapshots of the stationary electric field as predicted by our approximate model (a, HCMT) with numerical reference results (b, QUEP).
25 HIGHLIGHTED PUBLICATION: M. Hammer, Hybrid analytical/numerical coupled-mode modeling of guided wave devices, Journal of Lightwave Technology 25 (9), 2287-2298 (2007).
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BIOS LAB-ON-A-CHIP Miniaturized Electrochemical sensor array for on-line monitoring of fermentations The research in the BIOS Lab-on-a-Chip group focuses on 4 main themes, viz. micro- and nanofluidics, cells on chips, electrochemical systems and nanosensing and technology. Whereas the central expertise in the group is in electrical measurements and micro/nanofluidics, the themes have a clear link to life sciences, chemistry, and physics, and several collaborations in these fields have been established. One particular aim of BIOS is to demonstrate the importance of Labs on a Chip through relevant applications in the health domain. Besides involvement in on-going development of a Point of Care (POC) lithium analyzer carried out by the company Medimate, new research projects regarding cancer diagnostics and fertility analysis have been initiated recently.
Figure 1: Microscope picture of the sensor array.
The work highlighted here is a fine example of multidisciplinary work regularly carried out in the BIOS Lab-on-a-Chip group. It is about the design, modeling, and experimental characterization of an microfabricated electrochemical sensor array for on-line monitoring of fermentor conditions in both miniaturized cell assays and in industrial scale fermentations. In order to understand the processes to be monitored, co-operation is a must, in this case with the Department of Biotechnology, Delft University of Technology. Subsequently, the chemical variables to be monitored are identified and in this case proper electrochemical sensors are creatively chosen and designed to meet the requirements. Understanding of smart measuring techniques is required to obtain reliable and meaningful signals from the sensors. Last but not least, the design has to be implemented in real hardware, which is especially for a single-dice sensor array not an easy task. A photograph of the sensor array is shown in figure 1.
Figure 2: Comparison of biomass concentration measurements using dry weight (♦) and biomass sensor (□).
The viable biomass concentration is determined from impedance spectroscopy. As a miniaturized electrode configuration with high cell constant is applied, the spectral conductivity variation is monitored instead of the permittivity variation. Results of this sensor, shown in figure 2, indicate the actual change in biomass of a Candida utilis culture, compared to dry weight samples and show the expected successful behaviour of this device. The dissolved oxygen concentration is monitored amperometrically using an ultramicroelectrode (UME) array, which is shown to have negligible flow dependence. In figure 3, the results of an actual test-run in the Candida utilis culture shows the fine agreement of the UME signal and the conventional Clark oxygen electrode.
Figure 3: Comparison between the dissolved oxygen signals from the conventional Clark electrode (―) and the UMEA on the multi-sensor chip.
pH is monitored using an ion-sensitive field effect transistor (ISFET). A platinum thermistor is included for temperature measurements. All sensors were shown to be sufficiently accurate within the range relevant to yeast fermentations. The sensor array is shown to be very stable and durable and withstands steam-sterilization.
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The results obtained open the way to application of multisensor arrays in a 96-well plate format or even in the recently developed very high throughput screening formats (millionwell culture chips). On the other hand, micro- and nanosensor arrays may find important applications in the area of monitoring growth of single cells, such as blastocytes. �
HIGHLIGHTED PUBLICATIONS: [1] Krommenhoek, E.E. and Gardeniers, J.G.E. and Bomer, J.G. and Li, X. and Ottens, M and van Dedem, G.W.K. and van Leeuwen, M. and van Gulik, W.M. and van der Wielen, L.A.M. and Heijnen, J.J. and van den Berg, A., Integrated electrochemical sensor arry for on-line monitoring of yeast fermentations. Analytical Chemistry, 79 (15), (2007), 5567-5573. [2] Erik E. Krommenhoek, Michiel van Leeuwen, Han Gardeniers, Walter M. van Gulik, Albert van den Berg, Xiaonan Li, Marcel Ottens, Luuk A.M. van der Wielen, Joseph J. Heijnen, Lab-scale fermentation tests of micro chip with integrated electrochemical sensors for pH, temperature, dissolved oxygen and viable biomass concentration, Biotechnology and Bioengineering, 2007, DOI 10.1002/bit. 21661. [3] Ingham, C.J. and Sprenkels, A.J. and Bomer, J.G. and Molenaar, D. and van den Berg, A. and Van Hylckama Vlieg, J.E.T. and de Vos, W.M. , The micro-Petri dish, a million-well growth chip for the culture and high-troughput screening of microorganisms, Proceedings of the National Academy of Sciences of the United States of America, 104 (46), (2007), 18217-18222.
H I G H L I G H T S
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BIOPHYSICAL ENGINEERING Manipulating biomolecules with nanotechnology
We are a multidisciplinary team using nanotechnology and optical methods to manipulate, organize, visualize, and probe the biophysics of functional biological systems. Our interests are in quantitative measurements of molecular and cellular biophysical processes. We control and manipulate biomolecular functionality and visualize and quantify dynamic biophysical processes involving multiple molecular interactions in vitro and in living cells at high spatial, temporal, and chemical resolution. Supramolecular associations play a role in several of our projects: disease-related protein aggregation, the functional architecture of protein complexes, patterning of biomolecules, clustering of cell-surface molecules, and protein-nucleic acid interactions. Strong collaborations with other MESA+ groups are essential elements of our work, and fruitful links with Molecular Nanofabrication (MnF) and Complex Photonics Systems (COPS) are highlighted below.
Figure 1: LH2 protein complexes functionalized with adamantyl groups (guest molecules) immobilized onto β-CD (host molecules) chemically patterned substrate. (Left) AFM topography (liquid), FWHM 80 nm. (Right) Fluorescence-spectral image (false colour). The spectroscopic properties are not altered which suggests that the protein complex is intact upon patterning.
Nanopatterning Biomolecules Nature has evolved elegant processes that use nano-scale architectures to produce striking optical effects. For example, in photosynthesis, the harvesting of solar energy and its subsequent conversion into stable products depends on an interconnected macromolecular network of membrane associated chlorophyll-protein complexes, the light harvesting antenna complexes (LH2 and LH1). These systems have become archetypal molecular electronic devices due to their high excitation transfer rate (LH2→LH1→RC ~100 ps) and high efficiency (~95 %). PhD student Maryana EscalanteMarun is currently exploring the fabrication of nanostructures (combining nanoimprint lithography and supramolecular interactions) to investigate the specific adhesion, organization and functional properties of the light harvesting complexes. Such structures can contribute to our fundamental understanding of the biophysics of these photosynthetic proteins. Characterization is performed with a hybrid high resolution scanning probe microscope-spectral microscope to address organization and activity of the molecules. This work is in collaboration with the Molecular Nanofabrication group and with the University of Sheffield, UK.
Biophotonic Engineering with Photonic Nanostructures Researcher Christian Blum demonstrated that the apparent emission color of a fluorescent protein can be effectively controlled externally by a photonic crystal. A dramatic color change was observed with increasing crystal lattice parameter a, which appear in sync with the theoretically expected redistribution of light emission around the stop-band of the photonic crystal. His work demonstrates the potential of combining biological systems and the possibilities of protein engineering with the expanding toolbox of nanophotonics. This research is performed in close collaboration with the Complex Photonic Systems group. �
Figure 2: True color fluorescence images of the fluorescent protein DsRed2 embedded in different titania inverse opal photonic crystals show that the yellow-orange DsRed2 emission can be manipulated to red as well as to bright green. The local emission spectra illustrate this color change. The yellow bars indicate the photonic stop-bands, solid arrows indicate spectral areas where the emission is enhanced (up) and attenuated (down).
27 HIGHLIGHTED PUBLICATIONS: [1] Maryana Escalante, Pascale Maury, Christiaan M. Bruinink, Kees van der Werf, John D. Olsen, John A. Timney, Jurriaan Huskens, C Neil Hunter, Vinod Subramaniam, and Cees Otto. Directed assembly of functional light harvesting antenna complexes onto chemically patterned surfaces. Nanotechnology 19, 25101 (2008). [2] Nicholas P. Reynolds, Stefan Janusz, Maryana Escalante-Marun, John Timney, Robert E. Ducker, John D. Olsen, Cees Otto, Vinod Subramaniam, Graham J. Leggett, and C. Neil Hunter. Directed formation of Micro- and nanoscale patterns of functional light harvesting 2 complexes. J. Am. Chem. Soc. 129, 14625-31 (2007). [3] Christian Blum, Allard P. Mosk, Ivan S. Nikolaev, Vinod Subramaniam, and Willem L. Vos. Color control of natural fluorescent proteins by photonic crystals. Small 4, 492-496 (2008).
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C O M P U TAT I O N A L M AT E R I A L S S C I E N C E Graphite and graphene as perfect spin filters
Understanding the magnetic, optical, electrical and structural properties of solids in terms of their chemical composition and atomic structure by numerically solving the quantum mechanical equations describing the motion of the electrons is the central research activity of the group Computational Materials Science. When the equations contain no input from experiment other than the fundamental physical constants (charge and mass of the electron, Planck's constant and the speed of light), then it is possible to make statements about the properties of systems which are difficult to characterize experimentally or which have not yet been made. This is especially important as experimentalists begin to make hybrid structures approaching the nanoscale. The structure of graphene - a single layer of graphite - is such that the carbon pz states form two half occupied, constant velocity bands which intersect at the Fermi energy at the K point in reciprocal space, so that graphene is a zero gap semiconductor. This gives rise to a host of interesting properties which have only recently been observed experimentally. However, for device applications the constant velocity is problematic because it means that the electrons have an infinite effective mass which makes it impossible to control the transport properties by means of external fields. We have pointed out that graphene is almost perfectly lattice matched to hexagonal boron nitride (h-BN) and that placing a sheet of graphene on top of h-BN leads to the opening of a small gap at the Fermi energy and give the electrons a finite effective mass [1]. We have also observed that the in-plane lattice constants of graphene and graphite match the surface lattice constants of (111) Co, Ni and Cu almost perfectly and that these metals have no majority spin states near to the high symmetry K point at or close to the Fermi energy while ferromagnetic Co and Ni do have states with minority spin character there (figure 1) irrespective of whether they are fcc or hcp. It follows that in the absence of symmetry-lowering, perfect spin filtering should occur for graphite on top of a flat Ni or Co (111) surface. The effectiveness of the spin filtering is demonstrated for a currentperpendicular-to-the-plane (CPP) structure with n graphene layers sandwiched between semi-infinite Ni electrodes. Five layers of graphene are sufficient to attenuate the majority spin electrons essentially completely leading to an ideal magnetoresistance (figure 2). The spin filtering is quite insensitive to roughness and disorder (inset). �
28 HIGHLIGHTED PUBLICATIONS: [1] G. Giovannetti, P.A. Khomyakov, G. Brocks, P.J. Kelly and J. van den Brink, Phys. Rev. B 76, 073103 (2007). [2] V. M. Karpan, G. Giovannetti, P. A. Khomyakov, M. Talanana, A. A. Starikov, M. Zwierzycki, J. van den Brink, G. Brocks and P. J. Kelly, Phys. Rev. Lett. 99, 176602 (2007).
Figure 1: fcc Fermi surface (FS) projections onto a plane perpendicular to the [111] direction for Co majority (a) and minority (b) spins, for Ni majority (c) and minority (d) spins and for Cu (e). The number of FS sheets is shown by the color bar. For graphene and graphite, surfaces of constant energy are centered on the K point (f ).
Figure 2: Conductances of a Ni│Grn│Ni junction as a function of the number of graphene layers n for ideal junctions. Inset: magnetoresistance as a function of n for: (circles) ideal junctions; (diamonds) Ni│Grn│Cu50Ni50│Ni junctions where the surface layer is a disordered alloy; (squares) Ni│Grn│Ni junctions where the top layer of one of the electrodes is rough with only half of the top layer sites occupied (sketch).
H I G H L I G H T S
C O P S
COMPLEX PHOTONIC SYSTEMS Focusing of light through opaque scattering materials
The Complex Photonic Systems (COPS) group studies light propagation in ordered and disordered nanophotonic materials. We investigate photonic bandgap materials, random lasers, diffusion and Anderson localization of light. We recently pioneered control of spontaneous emission in photonic crystals and active control of the propagation of light in disordered photonic materials. Novel photonic nanostructures are fabricated and characterized mostly in the MESA+ cleanroom. Optical experiments are an essential aspect of our research, which COPS combines with a theoretical understanding of the properties of light. Our curiosity driven research is of interest to various industrial partners, and to applications in medical and biophysical imaging. Paper, white paint and skin are opaque materials, even though they do not absorb light. Instead, light is randomly scattered by nanoparticles in these materials. Since randomly scattered light has no preferential direction, it seems impossible to sharply focus light through a multiply scattering material (figure 1a, 1c). We have demonstrated that, surprisingly, a beam of laser light can be focused through an opaque medium. This is accomplished by shaping the incident wavefront using a liquid crystal phase modulator (figure 1b, 1d). The modulator consists of a twodimensional array of pixels, each controlling the phase of a ray of light. A learning algorithm finds the ideal phase of each of these rays, such that after hundreds of collisions in the medium, all rays interfere constructively to form a focus behind the material. The resulting focus is very tight and more than thousand times as intense as the background of scattered light. We expect our methods for controlling the propagation of scattered light to have applications in imaging and light delivery in scattering media, such as metal nanostructures and photonic metamaterials. ďż˝
Figure 1: Opaque lenses a) Light is scattered by sub-wavelength particles in an opaque white object. The light performs a random walk through the material and exits diffusely. b) By exactly matching the wavefront to scattering in the medium, the opaque object acts as a lens that focuses the light to a sharp spot. c) Measured transmitted intensity with an unshaped wavefront. Transmission is low and disordered. d) Measured transmitted intensity with a shaped wavefront. Light is focused to a point that is a thousand times more intense than the diffuse background (the range of the color scale was extended to display this very intense focus).
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HIGHLIGHTED PUBLICATIONS: [1] I. M. Vellekoop and A. P. Mosk: Focusing coherent light through opaque strongly scattering media, Optics Letters 32, 2309–2311 (2007). [2] I.S. Nikolaev, P. Lodahl, A.F. van Driel, A. F. Koenderink, and W.L. Vos: Strongly nonexponential time-resolved fluorescence of quantum-dot ensembles in three-dimensional photonic crystals, Phys. Rev. B 75, 115302: 1-5 (2007).
M E M S AE S +A
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C ATA LY T I C P R O C E S S E S A N D M AT E R I A L S Towards catalytic devices
The ambition of CPM is to build a bridge between IMPACT and MESA+ by developing new (heterogeneous) catalytic materials and devices, based on the expertise in MESA+, for practical application in chemical processes for sustainable energy and clean fossil energy, spearhead of IMPACT. The strategic alliance between MCS and CPM is an important asset to meet this ambition. The most prominent research cluster that has emerged so far is the controlled preparation of thin layers of carbon-nano-fibers on e.g. foam materials, in microchannels, on metal surface and in tubing. The applications ranges from catalyst support enabling accurate control of concentrations and temperature at the active site by preventing mass/heat transfer limitations, to composites, super-hydrophobic materials, to achieving slip flow in microfluidic devices (SRO Mesofluidics). Micro-reactors are also used for scientific purposes. E.g., micro-plasma reactors provide unique ability to study the interaction between radicals and (catalyst-) surfaces, relevant for high-temperature catalytic processes i.e. oxidative cracking. Also, microreactors with integrated sensors, e.g. IR spectroscopy (ATR), allow detailed studies of adsorbed species despite the presence of the fluid. On the longer term, CPM would like to use 3D nanotechnology for step-change improvements in catalyst synthesis. Participation in NNI as well as participation in the continuation of NRSCC is essential for taking up this challenge. �
Figure 1: Synthesis of thin layer of carbon-nanofibers on metallic substrates: SEM micrographs and a schematic representation (from ref 1).
Figure 2: Properties of adsorbed CO on Pt as well as the rate of oxidation depends on the presence of water, as observed with Attenuated-Total-Reflection IR spectroscopy (from ref 2).
30 HIGHLIGHTED PUBLICATIONS: [1] The reason for strong attachment of thin CNF layers on metal foams was identified: an micro-porous layer encompassing the feet of the CNFs is responsible for the effect. How CarbonNano-Fibers attach on Ni foam, J.K. Chinthaginjala, D. B. Thakur, K. Seshan, and L. Lefferts, submitted to Carbon. [2] ATR-IR provided new insight on effect of water on the oxidation of CO over Pt nano-particles. In situ ATR-IR study of CO adsorption and oxidation over Pt/Al2O3 in gas and aqueous phase: Promotion effects by water and pH, Sune D. Ebbesen, Barbara L. Mojet, and Leon Lefferts, JOURNAL OF CATALYSIS Volume: 246 Issue: 1 Pages: 66-73.
H I G H L I G H T S
I M S
I N O R G A N I C M AT E R I A L S S C I E N C E
Amazing electronic effects at oxide interfaces
The research group Inorganic Materials Science of the Faculty Science and Technology is involved in different aspects of science and technology of advanced inorganic materials on the nano-scale. Our goal is to elucidate the effects of size, structure, and interfaces of atomically controlled complex materials, with special attention to properties such as electronic and ionic conductivity, spin polarization, and ferroelectrics. At first sight, the exhibited phenomena look very diverse, but, and this is the uniqueness of the materials which are under investigation, the elements that control these phenomena, such as carrier doping and strong correlation of the carriers, are universal in these materials. Complex oxide materials start to play a very important role in electronic devices since they exhibit a broad range of functional properties, such as piezoelectricity and ferroelectricity, superconductivity, and ferromagnetism. Many of these phenomena occur in oxides that are lattice-matched, which enables fabrication of heteroepitaxial structures, in which the multiple degrees of freedom can be accessed. A new class of (nano) devices can be envisaged and engineered exploiting the novel functional properties of interfaces in oxides. A real breakthrough in this field is obtained by controlling on atomic scale the physical properties at the interfaces between different oxide materials. Electronic correlations, which control the electronic behavior of the material, are modified at the interface, and induce remarkable changes of the collective electronic and magnetic properties, to the extent that novel quantum states, not attainable in bulk, emerge. In collaboration with the Strategic Research Orientation Nano-Electronics and the Condensed Matter Physics and Devices group of MESA+ as well as the Geballe Laboratory for Advanced Materials, Stanford University we have intensively studied the electronic effects at oxide interfaces, especially interfaces between the wide-bandgap insulators SrTiO3 (STO) and LaAlO3 (LAO). Although both materials are non-conducting, the interface can become conducting in the case that the atomic stacking at the interface can be tuned [1]. More surprising, we observed magnetic effects at these interfaces. At very low temperature, below 300 mK, ferromagnetic ordering has been observed at the interface between the non-magnetic oxides. These results were published in Nature Materials, in July 2007 [2]. See the contribution of the Condensed Matter Physics and Devices group in this yearly report for a detailed description. Based on transport, spectroscopic, and oxygen-annealing experiments, it was also concluded that extrinsic defects in the form of oxygen vacancies introduced by the pulsed laser deposition process is an additional the source of the large carrier densities, especially when a low pressure is used during growth [3]. Finally, at intermediate deposition pressure, superconductivity is seen in these structures at temperatures below 300 mK. The aforementioned results indicate that the functionality of devices, fabricated from heteroepitaxial oxide multilayers, can be tuned by control of composition and structure of the interfaces. ďż˝ HIGHLIGHTED PUBLICATIONS: [1] M. Huijben, G. Rijnders, D.H.A. Blank, S. Bals, S. Van Aert, J. Verbeeck, G. Van Tendeloo, A. Brinkmand and H. Hilgenkamp, Nature Materials 5, 556 (2006). [2] A. Brinkman, M. Huijben, M. Van Zalk, J. Huijben, U. Zeitler, J.C. Maan, W.G. van der Wiel, G. Rijnders, D.H.A. Blank and H. Hilgenkamp, Nature Materials 6, 493 (2007). [3] W. Siemons, G. Koster, H. Yamamoto, W. A. Harrison, G. Lucovsky, Th.H. Geballe, D.H.A. Blank, and M.R. Beasley, Physical Review Letters 98, 196802 (2007).
Figure 1: Temperature dependence of the sheet resistance, RS, for n-type SrTiO3–LaAlO3 conducting interfaces, grown at various partial oxygen pressures. Three regimes can be distinguished: low pressures leads to oxygen vacancies, samples grown at high pressures show magnetism [2], whereas samples grown in the intermediate regime show superconductivity.
Figure 2: Photograph of the new COMAT cluster tool for deposition (pulsed laser deposition and e-beam deposition) and analysis (x-ray and ultraviolet photoelectron spectroscopy and scanning probe microscopy) of COmplex MATerials. This cluster tool is part of the nanolab facilities.
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I N T E G R AT E D O P T I C A L M I C R O S Y S T E M S Light amplification in Al 2 O 3 :Er on silicon
The Integrated Optical MicroSystems (IOMS) group performs research on both passive and active planar optical waveguide devices, for a variety of applications in optical sensing, biomedicine, and optical communication. These “optical chips” are realized in the MESA+ clean room facilities. For nanophotonic structures, like photonic crystals and Bragg gratings, both silicon and aluminum oxide layers are used, and are structured with ~10 nm resolution using focused ion beam (FIB) milling. Based on silicon oxynitride, optical microring resonators are employed as compact building blocks for the realization of complex integrated optical circuits. Devices such as wavelength filters, power splitters, tunable filters, optical switches, and modulators are realized. To this end, thermo-optic and electro-optic effects are exploited. The optical gain properties of
Figure 1: Micro-structured channel waveguide fabricated in an Al2O3 layer by RIE
actively doped amorphous (aluminum oxide) and crystalline (double tungstates) materials are investigated for light amplification, lasing, and modulation in integrated optical devices. Recently, a crystal growth laboratory has been established within the IOMS group for the in-house liquid phase epitaxy of such promising double-tungstate active layers.
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In 2005, we started the EU STREP project PI-OXIDE, which is coordinated by our group. The goal of this project was to develop a new optical materials system suitable for massfabricated active integrated optical circuits for telecommunications applications. Within this project, we have recently demonstrated net optical gain (amplification) within the important telecom signal wavelength range (around 1.53 µm) of up to 0.8 dB/cm in erbium-doped aluminum oxide waveguides. Thin Al2O3 layers were deposited on largescale thermally oxidized silicon substrates by a simple and reliable reactive sputtering technique [1]. The layer growth was optimized for very low optical background losses, a key requirement for net gain. In addition, a waveguide micro-structuring process was developed using chlorine-based reactive ion etching (RIE) for well-defined optical waveguides with widths down to 1.5 µm and heights of 500 nm, see Fig. 1, also with very low losses (0.21 dB/cm) [2]. Applying FIB, nano-structuring of reflection Bragg gratings in such Al2O3 channel waveguides has been investigated, resulting in functional reflection structures for wavelength selection, see Fig. 2. In order to activate the Al2O3 layers, Er3+ ions were incorporated during sputtering. This deposition method has also been optimized. To measure signal gain, light in the wavelength range of 1480-1600 nm from a tunable laser source was launched into an Al2O3:Er3+ channel waveguide. The erbium ions were excited by optical pump light at 980 nm which was simultaneously launched into the waveguide. Amplification was observed in the range of 1526-1567 nm up to a maximum value of 0.8 dB/cm [3], see Fig. 3. In the future, we will realize integrated devices with high active functionality, such as lasers and lossless power splitters, exploiting the new deposition and structuring tools described here. Follow-up funding for further applications of such devices has already been secured within the SmartMix project MEMPHIS. �
Figure 2: Nano-structured Bragg reflection grating fabricated in an Al2O3 channel waveguide by FIB
Figure 3: Optical absorption (without pumping) and gain (when optically pumped) over the wavelength range 1480-1600 nm in an Al2O3:Er3+ channel waveguide amplifier on silicon
HIGHLIGHTED PUBLICATIONS: [1] K. Wörhoff, F. Ay, M. Pollnau, "Optimization of low-loss Al2O3 waveguide fabrication for application in active integrated optical devices", ECS Transactions 3 (11), 17-26 (2006). [2] J.D.B. Bradley, F. Ay, K. Wörhoff, M. Pollnau, “Fabrication of low-loss channel waveguides in Al2O3 and Y2O3 layers by inductively coupled plasma reactive ion etching”, Applied Physics B 89 (2-3), 311-318 (2007). [3] F. Ay, J.D.B. Bradley, W.C.L. Hopman, V.J. Gadgil, R.M. de Ridder, K. Wörhoff, M. Pollnau, “Focused-ionbeam nano-structuring of Al2O3 dielectric layers for photonic applications", International Conference on Micro- and Nano-Engineering, Copenhagen, Denmark, 2007, Book of Abstracts, pp. 375-376. [4] J.D.B. Bradley, D. Geskus, T. Blauwendraat, F. Ay, K. Wörhoff, M. Pollnau, A. Kahn, H. Scheife, K. Petermann, G. Huber, "Growth, micro-structuring, spectroscopy, and optical gain in as-deposited Al2O3:Er3+ waveguides", Advanced Solid-State Photonics Conference, Nara, Japan, 2008, paper WB10.
H I G H L I G H T S
L P N O
LASER PHYSICS AND NONLINEAR OPTICS Nonlinear interaction between light and matter
The focus of the research in the Laser Physics and Nonlinear Optics (LPNO) group, which became a member in 2007, is the nonlinear interaction between light and matter. This spans from low to high-intensity nonlinear processes including XUV generation and optics. For studying interactions at ultra-high light intensities, the group is building the
Figure 1: Acceleration of electrons in wake of short laser pulse propagating in plasma
strongest laser system in the Netherlands. The group has a leading position on both CW optical parametric oscillators and XUV optics. For the exploration of interactions and processes in the THz range, work on compact photonic free-electron lasers aims to generate record output powers in this range.
Ultra-high intensity nonlinear processes. The group is developing a 20 TW Ti:Sapphire laser system (the strongest laser in the Netherlands) for a Laser Wakefield Accelerator (LWA) that will accelerate electrons to GeV kinetic energy over a distance of ~5 cm [1]. Currently, the laser delivers 2 TW, which is sufficient to drive the final amplifier into saturation. We have also studied the electron bunch dynamics, the effect of the vacuum-plasma transition and the ponderomotive scattering of electrons due to the interaction with the laser light just before injection into the plasma channel. These models are used to better understand and use the nonlinear dynamics. The 2 TW laser is also used to generate XUV radiation using enhanced High Harmonic Generation in a plasma channel. As a first step, we have demonstrated optical guiding of a laser pulse in a 2 cm long plasma channel.
Low intensity nonlinear processes. Optical parametric oscillators (OPOs) are tailored to emit coherent light in areas of the electromagnetic spectrum where no lasers exist. Our unique approach provides extremely rapid tuning, which we have taken advantage of to extend existing spectroscopic techniques to the mid-infrared. These light sources have prospective applications in spectral fingerprinting for both industrial monitoring and health applications. More recently, we have started to explore the optical nonlinear response of highly scattering media. Our theoretical work shows that an ultrashort pulse will be stretched and develops echo pulses after propagating through highly scattering media [2]. This is used to determine properties of sample types that are extremely relevant to the food and pharmaceutical industries. This research has the potential to revolutionise the way solid-state mixtures are monitored in these industries.
Free-electron lasers We successfully demonstrated lasing of a Cerenkov FEL, having a gain section of only 20 cm long and driven by a low current, low energy electron beam. Theoretical work of the group focused on an optical propagation code that interfaces with different FEL gain models to allow modelling of FEL oscillators. Several groups worldwide have started using this code. Near the end of the year, a proposal on photonic FELs was ranked first by STW. In this new project, we combine the properties of photonic structures with the principle of electron beam based coherent radiation sources to produce the innovative concept of a photonic free-electron laser, with the aim of a very compact source generating Watt-level THz radiation. � HIGHLIGHTED PUBLICATIONS: [1] A. Irman et. al., “Design and simulation of laser wakefield acceleration with external electron bunch injection in front of the laser pulse”. J. Appl. Phys., 102, 024513, 2007. [2] C.J. Lee et. al., “Using ultra-short pulses to determine particle size and density distributions“. Optics Express, 15, 2483, 2007.
Figure 2: Near infrared OPO
Figure 3: Pulse dispersed from a variety of random media
Figure 4: Schematic view of a photonic FEL
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Figure 5: Example of a photonic THz crystal (courtesy of R. Beigang, U. Kaiserslautern)
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LOW TEMPERATURE DIVISION Superconductor/ferromagnet junctions and spin-triplet superconductivity Superconductivity and ferromagnetism are two competing orders, however their interplay can be realized when the two interactions are spatially separated. In this case the coexistence of the two orderings is due to the so-called proximity effect. Experimentally this situation can be realized in superconductor/ferromagnet (SF) hybrid nanostructures. The main manifestation of the proximity effect in SF structures is the damped oscillatory behavior of the superconducting correlations in the F layers, resulting in a number of novel physical effects in nanoscale structures. In particular, nanoscale Josephson junctions with ferromagnetic interlayer (SFS junctions) recently attracted a lot of interest both from fundamental and practical point of view. SFS junctions have been proposed as potentially useful elements in superconducting logic circuits and Josephson
Figure 1: Experiment: (a) SFS Josephson junction with barrier from weak ferromagnet Ni60Cu40 (Weides et. al., Appl. Phys. Lett. 89, 122511 (2006)) and (b) from half-metallic ferromagnet CrO2 (Keizer et. al., Nature, 439, 825 (2006))
phase qubits.
In this work we provide quantitative theory of electronic transport in SFS Josephson junctions. The model describes quantitatively the oscillations of the critical current as a function of thickness of the ferromagnetic layer and materials parameters. The most striking phenomena are predicted in junctions with barriers from fully-polarized half-metallic (HF) ferromagnets. In this case only spin-triplet Cooper pairs can tunnel across the HF barrier while spin-singlet pairs can not. Up to now, in all known bulk superconductors only spin-singlet Cooper pairing is realized. However, in superconducting nanostructures spin-triplet pairing can occur in the ground state. We discuss in detail the properties of this spin-triplet pairing state and suggest the ways to detect triplet pairs using various types of junctions [1-4]. This study provides a tool to explain the existing experimental data in SFS junctions and to design new experiments. �
Figure 2: Theoretical model which takes into account arbitrary polarization in a ferromagnet (exchange field Vex) and spin–active interfaces between F and S layers.
Figure 3: Calculated local density of states (LDOS) in the center of the half-metallic barrier (S/HM/S case) which exhibits strong zero-bias anomaly. The case of SNS junction is shown for comparison when LDOS exhibits a minigap. Zero-bias anomaly in a half-metal is the signature of odd-frequency spin-triplet Cooper pairs and can be detected by STM.
34 HIGHLIGHTED PUBLICATIONS: [1] Y. Asano, Y. Tanaka, A.A.Golubov, ‘Josephson Effect due to Odd-Frequency Pairs in Diffusive Half Metals’, Phys. Rev. Lett. 98, 107002 (2007). [2] Y. Tanaka and A.A.Golubov, ‘Theory of the Proximity Effect in Junctions with Unconventional Superconductors’, Phys. Rev. Lett. 98, 037003 (2007). Y. Tanaka, A.A.Golubov, S. Kashiwaya, M.Ueda, ‘Anomalous Josephson Effect between Even- and OddFrequency Superconductors’, Phys. Rev. Lett. 99, 037005 (2007). [3] Y. Asano, Y. Tanaka and A.A.Golubov, S. Kashiwaya, Phys. Rev Lett. ‘Conductance Spectroscopy of Spin-Triplet Superconductors’, Phys. Rev. Lett. 99, 067005 (2007).
H I G H L I G H T S
LT-CMD
CONDENSED MATTER PHYSICS AND DEVICES - LOW TEMPERATURE DIVISION Magnetism at the interface between two non-magnetic materials
The Condensed Matter Physics and Devices group (CMD), headed by prof.dr.ir. Hans Hilgenkamp, carries out research on materials and structures with unconventional electronic properties, and their use in devices. The current research activities have a particular emphasis on high temperature superconductors and related perovskite oxides. High-resolution scanning SQUID magnetic microscopy presents a further focus area. The CMD group is part of the Low Temperature (LT) research division. Magnetic properties of materials are of interest for various applications as well as for the fundamental understanding of the interactions between electrons in these materials. For the first time, a combination of groups* from the MESA+ Institute for Nanotechnology have now observed magnetic effects at the interface between two non-magnetic, and even non-conducting, materials; SrTiO3 and LaAlO3.
Figure 1: Illustration of the physics of the charge transfer from the LaAlO3 into the TiO2 layers of the SrTiO3 , and electrical characteristics of a LaAlO3SrTiO3 heterostructure (from [2]).
When these insulating materials are connected, the interface surprisingly turns out to be either a good conductor or an insulator, depending on the atomic stacking sequence at the interface. This can be explained from the fact that the constituting layers in the LaAlO3 are charged, i.e. (LaO)+ and (AlO2)-, while the SrO and TiO2 layers building up the SrTiO3 are charge-neutral. As a result, at TiO2-LaO interfaces some of the electrons of the LaAlO3 are transferred into the TiO2 layers of the SrTiO3, where they can conduct electrical current. The complementary AlO2-SrO interfaces remain insulating, presumably because charge-transfer processes are balanced there by the creation of oxygen vacancies. Following up on our initial experiments on such interfaces [1], we have now studied the transport properties in a magnetic field, in collaboration with the National High Magnetic Field Laboratorium in Nijmegen. It turns out that the conducting interfaces are also magnetic. The magnetism manifest itself by a Kondo effect, in which the resistance increases logarithmically for decreasing temperature (see figure 1), by a strong decrease in resistance with applied magnetic field (a so-called negative magnetoresistance, see inset of figure 1), and a ferromagnetic ordering, occuring at temperatures below 300 mK. These results were published in Nature Materials, in July 2007 [2].
Figure 2: Artist impression illustrating the stacking of LaAlO3 and SrTiO3 layers. This image, made by MESA+ PhD-student Jeroen Huijben, was used by Science magazine to illustrate their Top 10 breakthroughs of the year 2007 (21 december 2007 issue) .
The interest in these complex oxide heterostructures is exemplified by the fact that Science Magazine has selected the research on these materials on rank 5 of its Top 10 of most important scientific developments of 2007, which they illustrated with figure 2 shown here. ďż˝ *: This research was carried out in a collaboration between the Condensed Matter Physics and Devices group, the Inorganic Materials Science group (see also their contribution in this yearly report) and the Strategic Research Orientation Nano-Electronics.
35 HIGHLIGHTED PUBLICATIONS: [1] M. Huijben, G. Rijnders, D.H.A. Blank, S. Bals, S. Van Aert, J. Verbeeck, G. Van Tendeloo, A. Brinkmand and H. Hilgenkamp, Nature Materials 5, 556 (2006). [2] A. Brinkman, M. Huijben, M. Van Zalk, J. Huijben, U. Zeitler, J.C. Maan, W.G. van der Wiel, G. Rijnders, D.H.A. Blank and H. Hilgenkamp, Nature Materials 6, 493 (2007).
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MESOSCALE CHEMICAL SYSTEMS Chemistry in Confinement
The Mesoscale Chemical Systems group studies the behaviour and control of liquid and gas-liquid mixtures on plain, nanostructured and reactive surfaces and interfaces in a confined environment, e.g. in a microreactor channel. The main research themes are: i. "exciting" chemistry in microreactors, focusing on microfluidic systems to which electronically controlled stimuli are applied in order to control the course of chemical reactions, ii. microfluidic process analytical technology (μPAT), focusing on integrated chromatography-based separation methods (a long-existing collaboration with the Free University of Brussels) and integrated spectroscopic techniques, and iii. enzymatic microreactor systems. The group is a very active user of the Cleanroom and collaborates with many of the groups participating in MESA+ and IMPACT, and has an organizational link with the CPM group.
Magnetic resonance in a liquid drop One of the highlights of the research of the group in 2007 was the development of a new concept of a microfluidic NMR chip. NMR, Nuclear Magnetic Resonance, is a versatile technique used frequently for the indentification of organic chemical compounds, but has many other application fields as well. Over the last decade, a trend can be observed towards NMR on smaller sample size, from milliliters in closed tubes, to several microliters in a capillary. MCS has extended this trend down to the sub-microliter scale. This will allow measurements on samples that are difficult to obtain in large quantities, like liquids withdrawn from specific organs of living organisms. However, optimizing a radio frequency (rf) coil, the conventional excitation-detection element for NMR, for small sample size with improved sensitivity and resolution is not trivial. In collaboration with the group of prof. Kentgens at Radboud University Nijmegen, the novel concept of a stripline, to replace the conventional microcoil, was investigated [1]. The stripline configuration gives a lower distortion of the static field used in NMR, resulting in a higher spectral resolution and a higher signal-to-noise ratio. It also allows much higher power input, which adds to the sensitivity. Figure 1 shows a photograph of the chip. It contains a microfluidic channel integrated in silicon, a copper stripline, and metallic shields at the outer surface of the chip in order to confine the rf field. A probe was designed which contains the microfluidic and electrical connections (figure 1). Using this fully integrated microfluidic chip containing 600 nl of pure ethanol (figure 2), a linewidth of 1 Hz at 600 MHz 1H-resonance (0.0017 ppm) was achieved, which allows baseline resolution of J-coupling [2]. With this, the device exhibits an unprecedented signal-to-noise ratio and spectral resolution comparable to state-of-the-art highresolution NMR, but for 1000 times smaller sample volumes. The chip is currently applied in metabolite studies of humane samples. �
36 HIGHLIGHTED PUBLICATIONS: [1] P.J.M. van Bentum, J.W.G. Janssen, A.P.M. Kentgens, J. Bart, J.G.E. Gardeniers, Stripline probes for nuclear magnetic resonance, J. Magn. Reson. 189 (2007) 104. [2] A.P.M. Kentgens,J. Bart, P.J.M. van Bentum, A. Brinkmann, E.R.H. van Eck, J.G.E. Gardeniers, J.W.G. Janssen, P. Knijn, S. Vasa, and M. H. W. Verkuijlen, High-resolution liquid- and solid-state nuclear magnetic resonance of nanoliter sample volumes using microcoil detectors, J. Chem.Phys. 128 (2008) 052202.
Figure 1: Left: Photograph of the two halves of a microfluidic NMR chip based on the stripline design showing the copper pattern forming a half-λ RF resonator on one half and the microfluidic channel on the other half. In the final device the two halfs are bonded together. Right: NMR probe with the stripline chip positioned vertically in the aluminum tube, and connected electrically (a) and fluidically (b).
Figure 2: Single-shot (i.e. only one RF pulse) 1H spectrum at 600 MHz of a 600 nl 100% ethanol sample. Signal-to-noise ratio is 5000, line width is 1 Hz.
H I G H L I G H T S
M N F
M O L E C U L A R N A N O F A B R I C AT I O N Model systems for cell recognition
The Molecular Nanofabrication (MnF) group, headed by Prof. Jurriaan Huskens, focuses on bottom-up nanofabrication methodologies and their integration with top-down surface structuring. Key research elements are: supramolecular chemistry at interfaces, multivalency, supramolecular materials, biomolecule assembly and cell patterning, nanoparticle assembly, soft and imprint lithography, microfluidics, and multistep integrated nanofabrication schemes. The group has several collaborations within MESA+, e.g. with the Biophysical Engineering group on the assembly of proteins on patterned surfaces, with the Membrane Technology group on porous stamps for microcontact printing, and with the Transducer Science and Technology group on edge lithography and its applications. Furthermore, the group actively participates in the MESA+ Strategic Research Orientation Nanofabrication, and in the flagship
Figure 1: Cyclodextrin vesicles bound to metalcomplexing ligands: with the strong-binding copper no coagulation occurs (left), while the weakerbinding nickel induces aggregation (right).
Nanofabrication in the national nanotechnology program NanoNed. Viruses and bacteria are able to couple to cells by small recognition points at cell membranes with which the cell normally communicates with its environment. The virus establishes a connection to all of these recognition points, the origin of cooperation, and is even capable to distort the cell membrane in order to gain as many interactions as possible. This complex interplay is sometimes counterintuitive, as was established by a study imitating the weak-interactions in a model system. Spherical doublewalled vesicles were used as model systems for cell membranes. These vesicles are equipped with receptor molecules, comparable to recognition points at the cell membrane. These receptor molecules recognize specific molecules. Those molecules in their turn couple to metal ions. The type of metal determines the strength of the binding. And there a surprising effect comes into play which is completely counterintuitive: a weaker binding metal, such as nickel, gives rise to a high degree of coagulation of the vesicles, while a strong binding metal does not induce coagulation. In their PNAS publication the authors explain this effect as follows. Copper does not leave “loose ends” because it interacts very strongly and does not leave unoccupied binding sites at the vesicle. Nickel, which binds much weaker, works more “sloppy” and binds in such a way that there are unoccupied binding sites available at the vesicle. This induces the vesicles to clamp to each other because the surfaces recognize each other and give rise to multiple interactions, which is also typical for the binding between a cell and a virus. The research gives thereby insight into the molecular recognition process, which is also applicable, for instance, in chips that recognize proteins. �
Figure 2: Molecules bind to receptors at the surface of a vesicles and nickel ions bind on the other sides of the molecules. Nickel binds rather weakly, and as a result leaves “loose ends” which results in interaction with other vesicles and thus causes coagulation of the vesicles.
37 HIGHLIGHTED PUBLICATION: C.W. Lim, O. Crespo-Biel, M. C. A. Stuart, D. N. Reinhoudt, J. Huskens, B. J. Ravoo, Proceedings of National Academy of Sciences of the USA 2007, 104, 6986-6991; "Intravesicular and intervesicular interaction by orthogonal multivalent host-guest and metal-ligand complexation".
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MEMBRANE TECHNOLOGY GROUP Fabrication and operation of polymeric microsieves
The Membrane Technology Group focuses on the multidisciplinary topic of membrane science and technology. We consider our expertise as a multidisciplinary knowledge chain ranging from molecule to process. The knowledge chain comprises the following elements: colloid and interface science, macroscopic mass transport characterization and modeling, material science and processing (both organic and inorganic), module and system design, and process technology. The research team is assembled such that permanent staff members cover one or more of the disciplines involved. The majority of the research deals with separation of molecular mixtures and selective mass transport. Our research program distinguishes five application clusters: sustainable membrane processes, water, biomedical and life science, inorganic membranes, and micro/nano structuring.
The cluster related to micro/nano structuring is embedded within the MESA+ research institute. In this cluster we are studying new fabrication methods for microstructured membranes and new opportunities that result from these structures. One striking example is the fabrication and filtration performance of polymeric microsieves. These microfiltration membranes are made out of polymers via a replication method. This allows for very cheap production, especially compared to their silicon based counterparts. Microsieves are characterized by a very uniform pore size and very thin selective layer. This results in extremely high fluxes during filtration. However, such high fluxes also make these membranes very sensitive towards fouling. Several strategies have been published to control the fouling of silicon based microsieves over the last few years. These strategies include backpulsing, air-sparging, and surface modification. Filtration experiments with the flexible polymeric microsieves indicated no fouling under certain backpulse conditions, as a result of the generated motion of the membrane. Stable fluxes could be obtained with backpulsing using feed (white beer) that would otherwise result in rapid flux decline without any backpulsing. �
38 HIGHLIGHTED PUBLICATIONS: [1] Gironès i Nogué, M.; Akbarsyah, I. J.; Bolhuis-Versteeg, L. A. M.; Lammertink, R. G. H.; Wessling, M. Vibrating polymeric microsieves: Antifouling strategies for microfiltration, Journal of Membrane Science 2006, 285, 323-333. [2] Gironès, M.; Akbarsyah, I. J.; Nijdam, W.; van Rijn, C. J. M.; Jansen, H. V.; Lammertink, R. G. H.; Wessling, M. Polymeric microsieves produced by phase separation micromolding, Journal of Membrane Science 2006, 283, 411-424.
Figure 1: Optical microscopy of polymeric microsieve with non-optimal blend composition (top). SEM images of optimized polymeric microsieves (bottom).
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M T P
M AT E R I A L S S C I E N C E A N D T E C H N O L O G Y O F P O LY M E R S Layer-by-Layer Constructed Porous Architectures Research in the group Materials Science and Technology of Polymers is focused on the molecular level understanding, manipulation and control of polymeric materials. Work is carried out in three clusters including (1) engineering and analysis of polymer surfaces and interfaces, nanotechnology, nanofabrication, and self-assembly; (2) morphology development and molecular order of polymers on the nanoscale; and (3) materials chemistry of polymers with defined molecular and mesoscopic structures with special attention to inorganic and organometallic polymers. High molar mass double-stranded DNA, a negatively charged polyelectrolyte, and cationic poly(ferrocenylsilane) were employed in a layer-by-layer deposition process to form porous structures on flat and on curved substrates. On planar substrates, initial DNA/PFS bilayers exhibited an irregular, web-like morphology. This 2-dimensional DNA network spontaneously evolved with increasing the number of deposited polyelectrolyte layers into a 3-dimensional hierarchical structure (figure 1). Colloidal particles of manganese carbonate were covered with DNA/PFS multilayers (SEM image, figure 2) as reported in Angew. Chem. Int. Ed. 2007, 46, 1702-1705, and on the inside cover of this journal (p. 1546). Removal of the templating core produced microcapsules with a porous wall. Confocal laser scanning microscopy showed that unlike conventional capsules, these DNA/PFS microcapsules display complete permeability to large molecules (66000 g mol-1 dextran, hydrodynamic radius 9 nm) and macromolecules (MRho-PSS, 120000 g mol-1).
Figure 1: Tapping mode Atomic Force Microscopy (AFM) height images of silicon wafers with a) polyethyleneimine (PEI) layer; b) PEI + one DNA/PFS bilayer (DNA/PFS)1; c) PEI + five DNA/PFS bilayers (DNA/PFS)5; d) PEI + (DNA/PFS)10, showing the
development of a 3-dimensional porous structure with an increasing number of polyelectrolyte bilayers. e) Top-view SEM image of a PEI + (DNA/PFS)10 film on silicon. The scale bar represents 1 μm.
The electrostatic self-assembly of polyelectrolytes with a high persistence length and chain length mismatch demonstrated here constitutes a new method for the fabrication of bio-compatible porous structures, which may have potential applications in new cell scaffold materials, gene therapy, biocompatible surfaces, and controlled, active, molecular release systems. �
Figure 2: Colloidal particles of manganese carbonate covered with multilayers of high-molar-mass doublestranded DNA and cationic poly(ferrocenylsilane) (PFS) polyelectrolytes (SEM image). The macroporous structures, confirmed also by AFM (inset image) were constructed by simple sequential supramolecular assembly controlled by the persistence length mismatch of the constituents. Upon MnCO3 core removal porous capsules were obtained.
39 HIGHLIGHTED PUBLICATION: Y. Ma, W.-F. Dong, M.A. Hempenius, H. Möhwald, G.J. Vancso, Layer-by-Layer Constructed Macroporous Architectures, Angewandte Chemie International Edition 2007, 46, 1702-1705.
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NANOELECTRONICS The best of both worlds: ferromagnetic semiconductors
Spintronics is the emerging technology in which solid-state electronic nanostructures based on the spin of electrons are developed. The interplay between magnetism, spin and electronic transport gives rise to a wealth of fascinating physics and new concepts. The NanoElectronics (NE) group aims to exploit these to design and create devices and components with unique functionality for applications in nanoelectronics and information storage. Important research lines are the fundamental physics of spinrelated phenomena, the implementation in electronic devices, the development of characterization techniques down to the scale of a single atomic spin, and the creation of new magnetic materials. Ferromagnetic semiconductors are a particularly attractive class of new materials as they have the properties of semiconductors and ferromagnets in a single material, thereby combining the best of both worlds. Such materials consist of a dilute concentration (a few %) of magnetic ions introduced into an otherwise non-magnetic host semiconductor. This transforms it into a ferromagnet, even though the average separation between individual magnetic ions is too large for them to interact directly. Instead, the magnetic coupling is provided by mobile charges (electrons or holes). This novel magnetic interaction mechanism provides a means to manipulate it, because the carrier density in a semiconductor is controllable by doping, electric fields and light. This offers exciting opportunities for the development of electronic devices with novel functionality, hence the worldwide interest in these materials. A key requirement of a ferromagnetic semiconductor is that the magnetic ordering survives up to elevated temperature, enabling applications in devices operating at room temperature. We therefore focus on oxide ferromagnetic semiconductors that exhibit this feature. As shown in figure 1, these materials can be fabricated with high structural quality thanks to the excellent facilities for pulsed laser deposition available at MESA+. The host semiconductor, TiO2 in anatase structural phase, is doped with 1.4 % of Co ions that provide the magnetic moments. The Co-doped TiO2 thin films are ferromagnetic and exhibit magnetic hysteresis at room temperature, as shown in figure 2. Furthermore, electronic transport shows that the material is an n-type semiconductor, while electronic as well as magnetic properties can be tuned by the deposition conditions. An exciting discovery is the Kondo effect we observed, as this is direct evidence for the interaction of the conduction electrons with the magnetic moments of the Co. Now, the remaining challenge is to demonstrate manipulation of the magnetism by an electric field. ďż˝
Figure 1: Structure of Co:TiO2 films with 1.4% Co imaged by transmission electron microscopy. Top panel shows a high resolution image of the surface region with lattice planes indicated. The bottom and middle panels show images near the interface with the SrTiO3 single crystal substrate, with the anatase unit cell indicated.
Figure 2: Magnetic moment versus magnetic field loops of Co:TiO2 films (1.4% Co) grown by pulsed laser deposition under different oxygen pressure, taken at room temperature with the field applied in the plane of the thin film. The observed magnetic hysteresis proves the existence of ferromagnetism at room temperature.
40 HIGHLIGHTED PUBLICATIONS: [1] R. Ramaneti, J.C. Lodder and R. Jansen, "Anomalous Hall effect in anatase Co:TiO2 ferromagnetic semiconductor", Applied Physics Letters 91, 012502 (2007). [2] R. Ramaneti, J.C. Lodder and R. Jansen, "Kondo effect and impurity band conduction in Co:TiO2 magnetic semiconductor", Physical Review B 76, 195207 (2007).
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OPTICAL SCIENCES Biomolecules and nanostructures
The Optical Sciences (OS) group studies the interaction of light and matter at the nanoscale. We do this by exploring ways to shape light and its environment. It's what we call active and passive control. Our current focus is on the interaction of light with biomolecules and nanostructures. In 2007 the group took on its new name, Optical Sciences, reflecting both its history (previously Optical Techniques) and new directions, as we shift the focus from developing new techniques to addressing more scientific questions in our research.
Active control Active control of the amplitude and phase of femtosecond light pulses allows us to create “optical melodies.” Such tailored pulse shapes can be fine tuned to one or more specific electronic and vibrational responses of a molecule to control its behavior in real time. We are pursuing applications in spectroscopy, medical diagnostics and/or treatment and the optimization of solar cell materials. The combination of broadband pulses and nonlinear (CARS) microscopy offers new opportunities for chemically-selective imaging and protein detection. Also in 2007, we developed a heterodyne detection technique that has improved sensitivity by more than 3 orders of magnitude [1]. This will enable CARS imaging at extremely low concentrations. Figure 1 shows CARS selective imaging of the sebaceous glands surrounding a hair follicle.
Figure 1: CARS selective imaging of lipids localized in the sebaceous glands surrounding a hair follicle.
Passive control The direct (nano-)environment of a molecule influences its interaction with light. Collective (plasmon) oscillations can be excited on structured surfaces, decay can be enhanced or delayed and light can be made to refract in extraordinary ways with the right combination of materials. We design and create these environments, and then study the light and molecules within them. In collaboration with the MTP group, we are exploring the optical properties of polymernanoparticle composites that are engineered to respond to environmental changes by shifting their emission wavelength. Using the Photon Scanning Tunneling Microscope (PSTM), which has been developed inhouse (figure 2), we have measured phase shifts of evanescent waves on glass and metal interfaces associated with Goos-Hänschen and Surface Plasmon Resonance effects [2]. � Figure 2: Probing phase shifts. (a) Schematic representation of the PSTM. (b) Measured evanescent waves on gold (left) and glass (right).
41 HIGHLIGHTED PUBLICATIONS: [1] M. Jurna, J. P. Korterik, C. Otto and H. L. Offerhaus and C. Otto “Shot noise limited heterodyne detection of CARS signals” Optics Express 15, 15207 (2007). [2] J. Jose, F.B. Segerink, J.P. Korterik and H.L. Offerhaus, "Near-field observation of spatial phase shifts associated with Goos-Hänschen and Surface Plasmon Resonance effects” Optics Express 16, 1958 (2008).
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PHYSICS OF COMPLEX FLUIDS Microscopic properties of the superhydrophobic state
The goal of the PCF group is to understand and control the structure and the mechanical properties of liquids on small scales ranging from a few nanometers to many micrometers. Our activities are cover the areas of: i) nanofluidics, ii) (electro)wetting & microfluidics, iii) soft matter mechanics. In nanofluidics we are interested in the range of validity of classical hydrodynamics and in its breakdown upon approaching molecular scales. In microfluidics we make use of the electrowetting effect to control the shape, the motion, and the generation of microdrops. These processes involve various challenging fundamental issues, such as contact angle hysteresis, the dynamics of contact lines, and hydrodynamic singularities. In soft matter mechanics, we are interested in the correlation between the internal structure of various types of complex
Figure 1: A water drop on a superhydrophobic surface illuminated with white light. The drop is in the superhydrophobic state, characterized by the entrapment of air in the texture, as shown in the lower left inset. The lower right inset sketches the undesired impregnated state. In the experiment, we investigate light diffracted from the liquid-water interface, which is determined by the shape of the micromenisci in the superhydrophobic.
fluids ranging from colloidal suspensions to living cells and their viscous and elastic properties. The PCF group contributes to the SROs Mesofluidics and Cell-Stress. To understand the transition between the beneficial superhydrophobic state and the undesired impregnated state of a superhydrophobic surface (see figure 1), a tool is needed that allows for investigating the microscopic properties of the water-substrate contact in a non-invasive manner. We introduced the use of optical diffraction to achieve this goal. By measuring the angular dependence of light diffracted from the surface, and comparing the measured diffraction intensities to calculated ones, we effectively solve the inverse diffraction problem, and we are able to measure the shape of the microscopic liquid-gas interfaces, that span between the ridges of the superhydrophobic texture, with nm resolution (see figure 2). This demonstrated the high accuracy of the method. In [1], we employ the optical diffraction to study also the dynamics of the microscopic liquid-gas menisci. By driving the menisci with an ultrasound field at variable frequency, we excite their collective oscillation and are able to measure their frequency response. The resonance frequency is found to be strongly decreased as compared to a single isolated meniscus, due to strong hydrodynamic coupling (see figure 3). �
42 HIGHLIGHTED PUBLICATION: Helmut Rathgen, Kazuyasu Sugiyama, Claus-Dieter Ohl, Detlef Lohse and Frieder Mugele. Nanometer-Resolved Collective Micromeniscus Oscillations through Optical Diffraction, Phys. Rev. Lett. 99, 214501 (2007).
Figure 2: Diffracted light intensity versus incident angle for various external pressures. The intensity variations above 50° reflect the interference between light reflected from the flat surface and the micromenisci, which become increasingly deflected upon increasing the pressure. The numerical data analysis (solid lines) performed using Rigorous Coupled Wave Analysis yields a nanometer sensitivity for the meniscus deflection.
Figure 3: Frequency response of an array of micromenisci. The experimental data (black dots) is in disagreement with the Stokes flow theory for a single meniscus (dashed blue line) and a simple model for the resonance frequency (pink bar), but agrees excellently with Stokes flow theory taking into account hydrodynamic interaction between adjacent micromenisci.
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PHYSICS OF FLUIDS Summary of nanofluidics activities 2007
The Physics of Fluids group is studying various flow phenomenona, in particular those related with bubbles. We use experimental, theoretical, and numerical techniques. Our main research areas are (i) Turbulence and Two-Phase Flow (ii) Granular Flow, (iii) Biomedical Application of Bubbles, and (iv) Micro- and Nanofluidics.
In the context of MESA+, the Physics of Fluids group dealt with the behavior of surface nanobubbles, thin films, and wetting phenomena on superhydrophobic surfaces. In recent years, numerous experiments revealed the existence of nanoscopic soft domains at the liquid-solid interface. The most consistent interpretation of these experiments is that the soft domains, which resemble spherical caps with height of the order of 10 nm and diameter of the order of 100 nm, are surface nanobubbles, i.e., nanoscale gas bubbles located at the liquid-solid interface. However, on the other hand, such nanobubbles should not exist: according to the experimental data these bubbles have a radius of curvature R smaller than 1μm, and therefore they should dissolve on timescales far below a second, due to a large Laplace pressure inside of the bubbles, which in a bubble with radius of e.g. 200 nm amounts to approximately 5 atm. In marked contrast the experiments reveal that nanobubbles are stable for periods as long as a few hours. In recent joint work with the Solid State Physics Chair (Profs. Poelsema and Zandvliet) we recently have quantitatively characterized the appearance, stability, density, and shape of surface nanobubbles on hydrophobic surfaces under varying conditions such as temperature and temperature variation, gas type and concentration, surfactants, and surface treatment. In joint work with the Chair of Julius Vancso we performed combined shock wave induced cavitation experiments and atomic force microscopy measurements of flat polyamide and hydrophobized silicon surfaces immersed in water. It was shown that surface nanobubbles, present on these surfaces, do not act as nucleation sites for cavitation bubbles, in contrast to the expectation. This implies that surface nanobubbles are not just stable under ambient conditions but also under enormous reduction of the liquid pressure down to −6MPa. We denote this feature as superstability. In the context of our work on contact line instabilities we report on our ongoing project with the inkjet printing company Océ: In piezo-acoustic inkjet printing nozzle failures are caused by an ink-layer on the nozzle-plate. It was experimentally shown that the ink-layer at the nozzle is formed through streamers of ink (see figure 2), emanating from a central ink-band on the nozzleplate. The streamers propagate over a wetting nanofilm of 13nm thickness and are directed towards the actuated nozzles. The front end of the streamers follows a power law in time with an exponent 1/2. The observations are consistent with surface tension gradient driven flow. The origin of this Maragoni flow is an effective lower surfactant concentration around the nozzle due to the meniscus oscillations. �
Figure 1: AFM topography images (tapping mode, height range: 11.1 nm) at different water temperature during immersion of the substrate. The water temperature ranges in intervals of 5K from 20˚ C (a) to 40˚ C (e). The dependence of the nanobubble density with water temperature is depicted in (f), showing a dramatic increase of the nanobubble density from 30˚ C to 35˚ C. The increase of the water temperature effectively leads to an oversaturation with gas of the water, facilitating nanobubble formation. Figure taken from “Characterization of surface nanobubbles”, Shangjiong Yang, Stephan Dammer, Stefan Kooij, Harold Zandvliet, and Detlef Lohse, Langmuir 23, 7072-7077 (2007).
Figure 2: Flow pattern on the nozzle-plate with one jetting nozzle. The central wetting band (top edge of the images) slowly deforms and a flow develops towards the jetting nozzle. Picture a: t = 20 s after the start of the actuation, b: t = 350 s, c: t = 390 s, d: t = 408 s, e: t = 428 s, f: t = 448 s. Figure taken from “Surface tension gradient driven flows on inkjet nozzle plates”, Jos de Jong, Hans Reinten, Herman Wijshoff, Marc van den Berg, Koos Delescen, Rini van Dongen, Frieder Mugele, Michel Versluis, and Detlef Lohse, Appl. Phys. Lett. 91, 204102 (2007).
43 HIGHLIGHTED PUBLICATIONS: [1] Surface nanobubbles do not act as bubble nuclei, Bram Borkent, Stephan Dammer, Holger Schönherr, Julius Vancso, and Detlef Lohse, Phys. Rev. Lett. 98, 204502 (2007); see also: “The Little Bubbles that Could”, Phys. Rev. Focus 19, story 16 (21 May 2007). [2] Spontaneous breakdown of superhydrophobicity, Mauro Sbragaglia, Christophe Pirat, Bram Borkent, Alisia Peters, Rob Lammertink, Matthias Wessling, and Detlef Lohse, Phys. Rev. Lett. 99, 156001 (2007). [3] Nanometer-resolved collective micromenisci oscillations through diffractive optics, Helmut Rathgen, Kazuyasu Sugiyama, Claus-Dieter Ohl, Detlef Lohse, and Frieder Mugele, Phys. Rev. Lett. 99, 214501 (2007). [4] Surface tension gradient driven flows on inkjet nozzle plates, Jos de Jong, Hans Reinten, Herman Wijshoff, Marc van den Berg, Koos Delescen, Rini van Dongen, Frieder Mugele, Michel Versluis, and Detlef Lohse, Appl. Phys. Lett. 91, 204102 (2007).
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SEMICONDUCTOR COMPONENTS Electrical band gap measurements in ultra thin silicon
The research program of Semiconductor Components (SC) deals with silicon-based technology and integrated-circuit devices. The research comprises thin film deposition and low-temperature processing; the integration of new components (such as silicon LED’s and elementary particle detectors) into CMOS; and advanced device physics and modelling. The group has strong ties with Philips, NXP Semiconductors, ASM International, and the CTIT-group IC-design, and is involved in the SRO nano-electronics. The Dutch Technology Foundation STW is its main funding source. Microchips contain ever smaller transistors. In a few years from now, the industry envisages to take the revolutionary step to use ultra-thin silicon films instead of bulk silicon for the transistor. These thin films of 5-25 nm allow a better electrostatic control over the semiconductor from all sides. New transistor shapes are proposed with these thin films, such as double-gate and FinFET transistors. The properties of silicon films thinner than ~10 nm however deviate from bulk-silicon. As the number of atoms in one dimension becomes low, the collective behaviour of the lattice changes, and interface effects become more prominent. One important change in the semiconductor is its increasing band gap with smaller crystal size (due to quantum confinement). This phenomenon has been widely investigated in recent years using optical techniques, such as photoluminescence. In the Thin Silicon project, financially supported by NXP, we aim for a compact yet accurate description of the device physics in extremely scaled silicon layers, preferably suitable for incorporation in circuit simulation software. Rather than optical data, it is electrical behaviour that should be well described in these models, to allow circuit design. As a step towards such a model, we developed a procedure to measure electrically the quantum confinement in the thin semiconductor film. Figure 1 shows a change in one of the fundamental semiconductor properties, the band gap alignment, when the silicon body thickness (tSi) is reduced to 5 nm. The values have been extracted from temperature dependent subthreshold current measurements on SOI Double Gate devices. With this method, changes in the band gap alignment can be measured separately from other device parameters such as the mobility. It is the first reported method to determine band offsets (and hence the band gap) of ultra-thin semiconductor films. �
44 HIGHLIGHTED PUBLICATION: J.-L.P.J. van der Steen, R.J.E. Hueting, G.D.J. Smit, T. Hoang, J. Holleman and J. Schmitz, “Valence band offset measurements on thin silicon-on-insulator MOSFETs,” IEEE Electron Device Letters, Vol. 28, No. 9, pp. 821-824 (September 2007).
Figure 1: A shift in the valence band edge is observed, which directly corresponds to an increasing band gap; tSi is the silicon body thickness in the measured devices, denoted with SOI in the upper figure.
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S E PA - N S T
STEHPS/CEPTES Societal, Ethical and Philosophical Aspects of NanoScience & Technology SEPA-NST aims at understanding the nature of nano-sciences and technologies (NST), the dynamics of their development and embedding in society, the ethical issues related to technological developments, and the possibilities to modulate these various developments. Participants in SEPA-NST come from STeHPS (MB) and CEPTES (GW). STeHPS - Science, Technology, Health and Policy Studies - is a department in the Faculty of Management and Governance, studying science and technology in society, including their governance, as well as health management issues and policy analysis. Their work on Constructive Technology Assessment, which combines analysis of ongoing technology developments and their embedding in society with feedback to and interaction with actors relevant for these developments and their uptake, is the main input in SEPA-NST. Such studies link analytical and normative perspectives, and consider technological innovations as well as innovations in governance. (http://www.mb.utwente.nl/stehps/) CEPTES - the Center for Philosophy of Technology and Engineering Science - of the Philosophy Department of the Faculty of Behavioural Sciences, aims to promote scholarship and research in the philosophy of technology and engineering science, and to encourage scholarly exchanges between philosophy, engineering science, and social science. (http://www.ceptes.nl/) Mutually related themes covered in SEPA-NST are: • Constructive technology assessment of NST. In 2007, workshops were organized (in collaboration with the Network of Excellence Frontiers) on strategic issues in research on drug delivery (in Aarhus), molecular machines (in Toulouse) and responsible innovation (in Twente). The methodology of socio-technical scenarios was developed further, including the role of institutional entrepreneurs putting broader issues on the agenda, e.g. for nanotechnology in the food packaging industry. • Societal embedding of NST, images, risk, social acceptance and ethics. A study of the practices of production and use of images of the nano-scale was concluded. The dynamics of current risk debates and regulation were analyzed. The ethics (“in the real world”) of scientists, industrialists and policy makers were studied. • Valorisation, entrepreneurship, science and innovation policy. Such issues were addressed in the study how governmental funding agencies attempt to meet the challenge of NST. • Challenges of NST to philosophy of science. How can we assess the quality of scientific research? Can we specify methodological approaches in the engineering sciences? How are scientific research and technological innovation related? Why is it so difficult to work multi- or inter-disciplinary. How are societal values to be embedded in scientific research? A philosophy of science in practice, with emphasis on how science is actually done, is necessary. • Workshops in Philosophy of Science for MESA+ PhD students and their supervisors. In these three-weekly workshops, we discuss philosophical themes relevant for scientific research, and scientific work of these PhD students. • The Society for Philosophy of Science in Practice (SPSP) http://www.gw.utwente.nl/spsp/, initiated by Mieke Boon in 2006, held its first biennial conference at Twente University, 23-25 August, 2007. � HIGHLIGHTED PUBLICATIONS: [1] Mieke Boon, 2008 (in press) Understanding according to the Engineering Sciences: Interpretative Structures, in: Scientific Understanding: Philosophical Perspectives, by Henk De Regt et.al. (eds.), University of Pittsburgh Press. [2] Pierre-Benoît Joly and Arie Rip, A Timely Harvest, Nature 450 (8 November 2007), p. 308.
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SUPRAMOLECULAR CHEMISTRY AND TECHNOLOGY Redox-Active Dendrimers on the Molecular Printboard The Supramolecular Chemistry and Technology (SMCT) group investigates macromolecular systems and the self assembly of molecules into functional nanoscale structures. Fields of applications are nanotechnology, sensor technology and diagnostics. Current topics include: supramolecular chemistry at interfaces, reactive microcontactprinting, nanoelectronics, single molecule chemistry, fluorescent sensor arrays, lab-on-a-chip, and magnetic resonance applications for bionano and medicinal applications. Most of these projects are related to nanotechnology as they strive for the control over the preparation, strength, and positioning of individual molecules and supramolecular assemblies. Recent achievements are: supramolecular liquid crystals, supramolecular tunnel junctions prepared by metal nanotransfer, and fluorescent patterns made by metal ion printing. The controlled immobilization of (bio)molecules at surfaces that respond to external stimuli is of interest in molecular electronics, biochips, solar cells, and for conducting single molecule experiments. Anchoring of molecules at surfaces usually proceeds by covalent attachment, chemisorption or physisorption, which are difficult to control. Within the SMCT group, the non-covalent immobilization of molecules has been developed by means of supramolecular interactions at so-called “molecular printboards”, which are self-assembled monolayers of (cyclodextrine) host molecules to which guest molecules can bind. This allows to tune the binding events of guests at the host surface precisely. Redox-active dendrimers are molecules that respond to an external stimulus, are multivalent guests, have a well-defined number of end groups, and the number of interactions with the molecular printboard can be controlled. For instance, the biferrocene (BFc) moiety forms host-guest inclusion complexes with the molecular printboard, but the complex formation is diminished upon oxidation.1 This enables the electrochemically controlled binding of very strongly interacting BFc dendrimers with the molecular printboard (figure 1). Moreover, due to the interaction of the BFc dendrimers with the molecular printboard, an additional oxidation state of the dendrimers is accessible. The combination of self-assembly, multivalency and redox activity provides the ability to alter and control immobilization of molecules precisely. This interdisciplinary research has been conducted in collaboration with a number of groups of MESA+. A detailed electrochemical study has been conducted in collaboration with Bernard Boukamp (Inorganic Materials Science).2 For molecular electronic applications, tunnel junctions consisting of molecular printboards and monolayers of redoxactive dendrimers (figure 2) were investigated in collaboration with the group of Jurriaan Schmitz (Semiconductor Components).3 A related system showing stair-case Coulomb blockade at room temperature was studied by STM in the group of Harold Zandvliet.4 �
46 HIGHLIGHTED PUBLICATIONS: [1] Nijhuis, C. A.; Dolatowska, K. A.; Ravoo, B. J.; Huskens, J.; Reinhoudt, D. N. Chemistry 2007, 13, 69. [2] Nijhuis, C. A.; Boukamp, B. A.; Ravoo, B. J.; Huskens, J.; Reinhoudt, D. N. J. Phys. Chem. C 2007, 111, 9799. [3] Nijhuis, C. A.; ter Maat, J.; Bisri, S. Z.; Weusthof, M. H. H.; Salm, C.; Schmitz, J.; Ravoo, B. J.; Huskens, J.; Reinhoudt, D. N. New. J. Chem. in press. [4] Nijhuis, C. A.; Oncel, N.; Huskens, J.; Zandvliet, H. J. W.; Poelsema, B.; Ravoo, B. J.; Reinhoudt, D. N. Small 2006, 2, 1422.
Figure 1: Electrochemically controlled interaction of the redox-active BFc dendrimers with the molecular printboard.
Figure 2: Micrograph of the two-terminal devices consisting of gold-molecular printboard/dendrimergold.
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S S P
S O L I D S TAT E P H Y S I C S Optical characterization of a percolating metal film
The research of the Solid State Physics (SSP) group focuses on the preparation and physical properties of materials in reduced dimensions. It incorporates surface science based methods to exercise control over materials on the nanometer scale, a search for new properties resulting from that size, and the (further) development of adequate research tools. Our research aims at providing fundamental principles for future application in nanotechnology. A broad spectrum of surface and interface features and properties is studied, using ultra-sensitive laterally averaging probes as well as techniques with high spatial resolution. Materials of potential interest for future applications inspire the choice of subjects. Potential applications include nano(opto)electronic and nano-magnetic devices and truly new materials, all based on improved understanding of the underlying physics and chemistry on the atomic and molecular scale. Our studies range from state-of-the-art ultra-high-vacuum based, curiosity driven experiments to strategic ones under ambient conditions. Deposition of a thin metal film on an isolating substrate starts from the nucleation of isolated islands followed by their selective enlargement. The coalescence of islands at the time of percolation is accompanied by the creation of an electrically conducting path across the surface. The various stages of Ag growth (figure 1) have a markedly different optical response, which was studied using spectroscopic. Nucleation sites are initially created by Au nanoparticles, which exhibit a plasmonic absorption feature, which is characterized by a Lorentzian shape (figure 2). The strength and width of this resonance are related to the density of conduction electrons N and the electron relaxation time Ď„, respectively. The particles were subsequently enlarged by electroless Ag deposition, resulting in a red-shift of the resonance energy E0 and a discontinuous increase of the electron relaxation time at percolation. The optically determined conductivity is very similar to results obtained from DC resistance measurements. The maximum absorption or resonance energy is very different for a particulate or continuous metal film. For a continuous film the resonance energy has shifted to zero and the optical response is characterized by a Drude shape. This red-shift results from a change in particle shape, the interaction with surrounding particles and image dipole contributions. A rigorous analysis allow us to relate these effects to the depolarization factor L of the individual particles, which is proportional to the square of the resonance energy (figure 2). The change of L with time before percolation can therefore directly be related to the average shape and size of the growing entities. ďż˝
Figure 1: Scanning electron microscopy images (700nmx700nm) of different stages of a growing metal film: a) Au particle nucleation sites, b) initial enlargement with silver, c) after percolation, and d) continuous metal film.
Figure 2: Change of the depolarization factor L with time as obtained from the position of the absorption resonance energy of the thin film. Indicated are situations starting with 24% (red) and 5% (green) surface coverage of nucleation sites. The inset shows the optical absorption for a Lorentzian (red) and Drude (blue) lineshape.
47 HIGHLIGHTED PUBLICATION: A.J. de Vries, E.S. Kooij, H. Wormeester, A.A. Mewe and B. Poelsema, Ellipsometric study of percolation in electroless deposited silver films, Journal of Applied Physics 101 (2007) 053703.
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PHYSICAL ASPECTS OF NANOELECTRONICS - S O L I D S TAT E P H Y S I C S Atom manipulation at room temperature The research of the group Physical aspects of NanoElectronics (PNE) is devoted to the understanding of nanometer-sized building blocks (including single or small groups of molecules) in device-based structures, that constitutes fundamental units for electronic components such as nanowires, switches, memory and gain elements. At nanometer length scales quantum phenomena start to play an important role. For low-dimensional systems one expects a wealth of exotic physical phenomena, such as non-Fermi liquid behavior, Coulomb blockade, charge-density wave condensation due to a Peierls instability, quantization of conductance etc. In order to obtain a deeper insight into the behavior of these nanoscale devices the physical, chemical and especially electronic properties are studied with with high spatial resolution techniques. The possibility of controlled local demolition and repair of recently discovered selforganized Pt-nanowires on Ge(001) surfaces has been explored. These nanowires are composed of Pt-dimers, which are found to be rather weakly bound to the underlying substrate. Using this property, we demonstrate the possibility of carrying the constituting dimers of the Pt-nanowires from point to point with atomic precision at room temperature (see figure 1). Pt-dimers can be picked-up in two configurations: (i) a horizontal configuration at the tip apex, resulting in double tip images (figure 2(a)) and (ii) a configuration where the Pt dimer is attached to the side of the tip apex, resulting in welldefined atomically resolved images (figure 2(c)). ďż˝
48 HIGHLIGHTED PUBLICATION: O. Gurlu, A. van Houselt, W.H.A. Thijssen, J.M. van Ruitenbeek, B. Poelsema, and H.J.W. Zandvliet, Nanotechnology 18, 365305 (2007).
Figure 1: An array of 5 Pt nanowires on a Ge(001) surface. (a) Nanowire 1 has a large defect, which consists of 4 missing Pt dimers (upper left). (b) Four individual Pt dimers are picked up from nanowire 2 and dragged to the defect of nanowire 1. The dimers are picked up and displaced in a one-by-one fashion by the STM tip. Image size is 10 by 10 nm, tunneling current is 0.4 nA and -20 mV sample bias. The atom manipulation experiments are performed at room temperature.
Figure 2: (a) STM image (10 x 10 nm) recorded on an array of Pt nanowires just after a single dimer pickup event, resulting in a double tip image (configuration I). (b) STM image (10 x 3 nm) on which a Pt dimer is dropped from the STM tip during imaging. The lower half of the image is scanned with a double tip (Pt dimer at the tip apex in configuration I), while the upper half of the image, after the dropping event, is again atomically sharp. (c) STM image (10 x 10 nm) recorded on an array of Pt nanowires. In the middle of the image a single dimer is picked up from one of the Pt chains. The resolution of the STM image remains essentially unaltered (Pt dimer at the tip apex in configuration II). The small lateral shift of the image is due to the exact position of the Pt dimer with respect to the apex of the STM tip.
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TRANSDUCER SCIENCE AND TECHNOLOGY Micro flow sensors based on surface channel technology
The Transducer Science and Technology (TST) group has a history and focus on micro system technology. The research is highly multidisciplinary, ranging from the millimeter down to the nanometer range, including physical concepts, materials and micro- and nanofabrication technology, as well as system aspects. The extensive technological research program and the versatile high quality MESA+ cleanroom facilities allow the group to fabricate and investigate transducers off the beaten paths offered e.g. through foundry processes. Applications are clustered around Sensors, Actuators, Micro and nanofluidics and probe based data storage.
MEMS fluidic devices often require the integration of transducer structures with freely suspended microchannels. To this end we have developed a versatile microchannel fabrication concept, allowing for easy fluidic interfacing and integration of transducer structures in close proximity to the fluid. This is achieved by the reliable fabrication of completely sealed microchannels directly below the substrate surface (figure 1). The resulting planar substrate surface allows for the deposition of transducer material on top of the channels and pattern transfer by lithography. The microchannels are subsequently released and fluidic entrance holes are created, while the transducer structures can be protected by photoresist. Several monolithic microfluidic device structures have been fabricated, demonstrating the versatility of the concept. Fabricated surface microchannel devices can optionally be vacuum sealed by anodic bonding.
Figure 1: Cross-section of sealed surface microchannels.
Figure 2: Thermal flow sensor on a freely suspended microchannel.
One example of a device that can be realized in this technology is a thermal flow sensor with a heater and temperature sensors on top of a channel segment that is thermally isolated from the silicon substrate (figure 2). In this way, heat loss to the substrate is minimized. Another example of a successfully fabricated device is a flow sensor based on the Coriolis effect (figure 3). A freely suspended part of the channel is brought into vibration and Coriolis forces acting on the moving mass inside the channel result in a secondary vibration in a different mode of which the amplitude is a measure for the mass flow. An important advantage of Coriolis-based flow sensors is that they are sensitive to the true mass flow, independent of flow profile, pressure, temperature and properties of the fluid (density, viscosity, etc.). Because of the high ratio between the mass moving inside the channel and the mass of the channel itself (thanks to the extremely thin channel wall) and the relatively high resonance frequencies of micromachined structures an accuracy better than 0.01 gram per hour was demonstrated. �
Figure 3: Resonant tube structure (10 mm long, 40 µm diameter) of a Coriolis-force based flow sensor.
49 HIGHLIGHTED PUBLICATIONS: [1] Dijkstra M., De Boer M.J., Berenschot J.W., Lammerink T.S.J., Wiegerink R.J., Elwenspoek M., A versatile surface channel concept for microfluidic applications, J. Micromech. Microeng., 17, 2007, 1971–1977. [2] Dijkstra M., De Boer M.J., Berenschot J.W., Lammerink T.S.J., Wiegerink R.J., Elwenspoek M., Miniaturized flow sensor with planar integrated sensor structures on semicircular surface channels, Proceedings MEMS 2007, Kobe, Japan, 21-25 January 2007. [3] Haneveld J., Lammerink T.S.J., Dijkstra M., Droogendijk H., De Boer M.J., Wiegerink R.J., Highly sensitive micro Coriolis mass flow sensor, Proceedings MEMS 2008, Tucson, U.S.A., 13-17 January 2008.
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M esa + S cientific P u b l ications 2 0 0 7 PHD THESES Benito lopez, F. (2007, April 05). High Pressue: a Challenge for Lab-on-a-chip Technology. UT University of Twente (183 p.) (Zutphen: Wรถhrmann Print Service). Prom./coprom.: prof.dr.ir. D.N. Reinhoudt & Dr. W. Verboom. Casper, L.C. (2007, May 25). On the operation of a long-pulse KrCl excimer laser. UT University of Twente (152 p.) (Enschede: University of Twente). Prom./coprom.: Prof. K.J. Boller & Dr.ing. H.M.J. Bastiaens. Dam, H.H. (2007, May 16). New Ligands for Americium: a combinatorial Approach. UT University of Twente (167 p.) (Zutphen: Wรถhrmann Print Service). Prom./coprom.: prof.dr.ir. D.N. Reinhoudt & Dr. W. Verboom. Dekkers, J.M. (2007, March 08). Transparent Conducting Oxides on Polymeric Substrates by Pulsed Laser Deposition. UT University of Twente (146 p.) (Zutphen: Wohrmann Print Service). Prom./coprom.: Prof.Dr.Ing. D.H.A. Blank & Dr ing. A.J.H.M. Rijnders. Ebbesen, S.D. (2007, March 08). Spectroscopy under the Surface. In-Situ ATR-IR Studies of Heterogeneous Catalysis in Water. UT University of Twente (177 p.) (Enschede: Gildeprint B.V.). Prom./coprom.: Prof.dr.ir. L. Lefferts & dr. B.L. Mojet. Emmelkamp, J. (2007, May 04). An integrated micro bi-directional dosing system for single cell analysis on-chip. UT University of Twente (178 p.) (Zutphen: Wohrmann Print Service). Prom./ coprom.: prof.dr.ir. A. van den Berg & E.T. Carlen. Euser, T.G. (2007, March 02). Ultrafast optical switching of photonic crystals. UT University of Twente (164 p.) (Enschede: Printpartners Ipskamp). Prom./coprom.: Prof.dr. W.L. Vos. Fazal, I. (2007, October 19). Development of a gas microvalve based on fine and micromachining. UT University of Twente (157 p.) (Enschede: University of Twente). Prom./coprom.: prof.dr. M.C. Elwenspoek, dr.ir. H.V. Jansen, prof.dr.ir. A. van den Berg, prof.dr. J.G.E. Gardeniers, E.P. Enoksson, J. Muller, R. Zengerle & ir. J.C. Lotters. Fuente Valentin, M.I. de la (2007, March 09). Theory, Design and Operation of a Compact Cerenkov Free-Electron Laser. UT University of Twente (125 p.) (Enschede: University of Twente). Prom./coprom.: Prof. K.J. Boller & Dr. P.J.M. van der Slot. Harutyunyan, D. (2007, May 25). Adaptive Vector Finite Element Methods for the Maxwell Equations. UT University of Twente (194 p.) (Zutphen: Wohrmann Print Service). Prom./coprom.: prof.dr.ir. J.J.W. van der Vegt & dr. M.A. Botchev. Hoang, T. (2007, September 28). High efficient infrared-light emission from silicon leds. UT University of Twente (Enschede). Prom./coprom.: prof.dr. J. Schmitz. Hoexum, A.M. (2007, April 26). Unleashed Microactuators electrostatic wireless actuation for probe-based data storage. UT University of Twente (208 p.) (Zutphen: Koninklijke Wohrmann). Prom./coprom.: prof.dr. J.C. Lodder, dr.ir. L. Abelmann & dr.ir. G.J.M. Krijnen. Hopman, W.C.L. (2007, April 20). Light-Flow Characterization and Manipulation in 1 and 2 Dimensional Photonic Crystals. UT University of Twente (165 p.) (Enschede, The Netherlands: Wohrmann Print Service). Prom./coprom.: prof.dr. M. Pollnau, prof.dr. A. Driessen & dr.ir. R.M. de Ridder. Hussein, M.G. (2007, February 23). Optimization of PECVD boron-phosphorus doped silicon oxynitriide for low-loss optical waveguides. UT University of Twente. Prom./coprom.: prof.dr. A. Driessen. Klein, E.J. (2007, April 11). Densely integrated microring-resonator based components for fiberto-the-home applications. UT University of Twente (223 p.) (Enschede, The Netherlands: University of Twente). Prom./coprom.: prof.dr. A. Driessen. Krommenhoek, E.E. (2007, November 29). Integrated sensor array for on-line monitoring micro bioreactors. Univ. of Twente (170 p.) (Enschede: Print Partners Ipskamp). Prom./coprom.: prof.dr.ir. A. van den Berg & prof.dr. J.G.E. Gardeniers. Ludden, M.J.W. (2007, September 21). Molecular printboards as general platforms for protein immobilization. UT University of Twente (185 p.) (Enschede: Printpartners Ipskamp). Prom./coprom.: Prof.dr.ir. J. Huskens & prof.dr.ir. D.N. Reinhoudt.
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Martin, D. (2007, November 07). Development of superconducting tunnel junction arrays for astronomical observations. UT University of Twente (143 p.) (Enschede). Prom./coprom.: Prof. H. Rogalla, Dr. A. Golubov & Dr. A. Peacock. Mathew, D. (2007, April 27). High pressure discharge instabilities in Fluorine based excimer laser gas mixtures. UT University of Twente (138 p.) (Enschede: University of Twente). Prom./coprom.: Prof. K.J. Boller & Dr.ing. H.M.J. Bastiaens. Mathews, M. (2007, November 22). Structural and magnetic properties of epitaxial La0.67Sr0.33MNO3 films and nanostructures. UT University of Twente (144 p.) (Zutphen: Wohrmann Print Service). Prom./coprom.: Prof.Dr.Ing. D.H.A. Blank, prof.dr. J.C. Lodder, Dr ing. A.J.H.M. Rijnders & dr. R. Jansen. Maury, P.A. (2007, January 26). Fabrication of nanoparticle and protein nanostructures using nanoimprint lithography. UT University of Twente (154 p.) (Zutphen: Wöhrmann Print Service). Prom./coprom.: Prof.dr.ir. J. Huskens & Prof.dr.ir. D.N. Reinhoudt. Mewe, A.A. (2007, February 09). Nanocolloidal route to smart wiring: Electroless metal growth on gold nanoparticles, selectively adsorbed on locally functionalised oxide surfaces. UT University of Twente (116 p.) (Enschede, the Netherlands: Solid State Physics group). Prom./coprom.: Prof. dr.ir. B. Poelsema. Min, B.C. (2007, August 31). Interface engineering of spintunnel contacts to silicon - Towards silicon-based spintronic devices. UT University of Twente (Enschede: University of Twente). Prom./ coprom.: prof.dr. J.C. Lodder. Molen, K.L. van der (2007, April 25). Experiments on scattering lasers from Mie to random. UT University of Twente (128 p.) (Enschede: Printpartners Ipskamp). Prom./coprom.: Prof.dr. A. Lagendijk & Dr. A.P. Mosk. Nedelcu, I.N. (2007, September 07). Interface structure and interdiffusion in Mo/Si multilayers. UT University of Twente (129 p.). Prom./coprom.: Dr. F. Bijkerk. Nguyen, Q.D. (2007, August 27). Electrochemistry in anisotropic etching of silicon in alkaline solutions. UT University of Twente (167 p.) (Enschede: University of Twente). Prom./coprom.: prof. dr. M.C. Elwenspoek, E.K. Sato, P. French, J.J. Kelly, E. Vlieg, dr. J.G.E. Gardeniers, dr.ir. H.V. Jansen & E. Veenendaal, van. Nicollian, P.E. (2007, August 31). Physics of Trap Generation and Electrical Breakdown in Ultrathin SiO2 and SiON Gate Dielectric Materials. Univ. of Twente (175 p.) (Enschede, The Netherlands: Ipskamp). Prom./coprom.: prof.dr. J. Schmitz & prof.dr.ir. F.G. Kuper. Oncel, N. (2007, June 28). Scanning tunneling microscopy and spectroscopic studies on Ptmodified Ge(001) and metallic (Pd, Au) - quantum dots on self-assembled monolayers. UT University of Twente (108 p.) (Enschede, the Netherlands: Solid State Physics group). Prom./coprom.: prof. dr.ir. H.J.W. Zandvliet & Prof.dr.ir. B. Poelsema. Piermattei, A. (2007, May 03). Liquid Crystalline Hydrogen-Bonded Rosettes. UT University of Twente (163 p.) (Zutphen: Wöhrmann Print Service). Prom./coprom.: prof.dr.ir. D.N. Reinhoudt & Dr. M. Crego Calama. Radosevic-Zivkovic, T. (2007, November 29). Thin Supported Silica Membranes. UT University of Twente (126 p.) (Zutphen: Wöhrmann Print Service BV). Prom./coprom.: Prof.Dr.Ing. D.H.A. Blank, Prof.dr.ir. A. NijMayjer & Dr. H.J.M. Bouwmeester. Revermann, T. (2007, February 02). Methods and instrumentation for quantitative microchip capillary electrophoresis. UT University of Twente. Prom./coprom.: Prof.dr. U. Karst. Roerdink, M. (2007, April 05). Macromolecule-Substrate Interactins in Directed Self-Assembly. From Tailored Block Copolymers with Polyferrocenylsilanes towards Functional Nanoplatforms. UT University of Twente (163 p.) (Enschede: PrintPartners Ipskamp). Prom./coprom.: Prof.dr. G.J. Vancso & Dr. M.A. Hempenius. Rozkiewicz, D.I. (2007, October 18). Covalent Microcontact Printing of Biomolecules. UT University of Twente (156 p.) (Zutphen: Wöhrmann Print Service). Prom./coprom.: prof.dr.ir. D.N. Reinhoudt & Dr. B.J. Ravoo. Rusu, P.C. (2007, October 25). Charge transfer and dipole formation at metal-organic interfaces. UT University of Twente (115 p.) (Enschede: Gildeprint). Prom./coprom.: Prof.dr. P.J. Kelly & Dr. G. Brocks.
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Sandtke, M. (2007, June 29). Surface plasmon polariton propagation in straight and tailored waveguides. UT University of Twente (106 p.) ( Ponsen & Looijen B.V.). Prom./coprom.: Prof dr. L. Kuipers. Savels, T. (2007, February 14). Scattering Lasers. UT University of Twente (159 p.) (Enschede: Printpartners Ipskamp). Prom./coprom.: Prof.dr. A. Lagendijk & Dr. A.P. Mosk. Seiwert, B. (2007, July 06). Ferrocene-based derivatizing agents for LC/MS and LC/EC/MS. UT University of Twente. Prom./coprom.: Prof.dr. U. Karst. Song, J. (2007, November 28). New Approaches in the Engineering and Characterization of Macromolecular Interfaces Across the Length Scales: Applications to Hydrophobic and Stimulus Responsive Polymers. UT University of Twente (205 p.) (Zutphen, The Netherlands: Wรถhrmann Print Service). Prom./coprom.: Prof.dr. G.J. Vancso. Troeman, A.G.P. (2007, December 13). NanoSQUID Magnetometers and High Resolution Scanning SQUID Microscopy. UT University of Twente (130 p.) (Enschede: Print Partners Ipskamp, Enschede). Prom./coprom.: prof. H. Hilgenkamp. Wolbers, F. (2007, June 08). Apoptosis chip for drug screening. UT University of Twente (214 p.) (Zutphen: Wohrmann Print Service). Prom./coprom.: prof.dr.ir. A. van den Berg, Prof.dr. I. Vermes & S.M.H. Andersson.
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ACADEMIC JOURNAL REFEREED (RANKED BY IMPACT FACTOR) Berg, G.B. van den & Wessling, M., Nanofluidics - Silicon for the perfect membrane, Nature 445 (2007) 726-726. Brinkman, A., Huijben, M., Zalk, M. van, Huijben, J., Zeitler, U., Maan, J.C., Wiel, W.G. van der, Rijnders, A.J.H.M., Blank, D.H.A. & Hilgenkamp, H., Magnetic effects at the interface between nonmagnetic oxides, Nature materials 6 (2007) 493-496. Engelen, R.J.P., Sugimoto, Y., Gersen, H., Ikeda, N., Asakawa, K. & Kuipers, L., Ultrafast evolution of photonic eigenstates in k-space, Nature physics 3 (2007) 401-405. Jansen, R., Silicon takes a spin, Nature physics 3(8) (2007) 521-522. Basabe-Desmonts, L., Reinhoudt, D.N. & Crego Calama, M., Design of fluorescent materials for chemical sensing, Chemical Society reviews 36 (2007) 993-1011. Dam, H.H., Reinhoudt, D.N., Reinhoudt, D.N. & Verboom, W., Multicoordinate ligands for actinide/ lanthanide separtations, Chemical Society reviews 36 (2007) 367-377. Li, X., Reinhoudt, D.N., Reinhoudt, D.N. & Crego Calama, M., What do we need for a superhydrophobic surface? A review on the recent progress in the preparation of superhydrophobic surfaces, Chemical Society reviews 36 (2007) 1350-1368. Crivillers, N., Mas Torrent, M., Perruchas, S., Roques, N., Vidal Gancedo, J., Veciana, J., Rovira, C., Basabe desmonts, M.L., Ravoo, B.J., Crego Calama, M. & Reinhoudt, D.N., Self-assembled monolayers of a multifunctional organic radical, Angewandte Chemie, International Edition in English 46 (2007) 2215-2219. Ludden, M.J.W., Mulder, A., Tampé, R., Reinhoudt, D.N. & Huskens, J., Molecular printboards as a general platform for protein immobilization: A supramolecular solution to nonspecific adsorption, Angewandte Chemie, International Edition in English 46 (2007) 4104-4107. Ma, Y., Dong, W.F., Hempenius, M.A., Möhwald, H. & Vancso, G.J., Layer-by-Layer Constructed Macroporous Architectures, Angewandte Chemie, International Edition in English 46 (2007) 1702-1705. Oshovsky, G., Reinhoudt, D.N. & Verboom, W., Supramolecular chemistry in water, Angewandte Chemie, International Edition in English 46 (2007) 2366-2393. Shi, W., Giannotti, M.I., Zhang, X., Hempenius, M.A., Schönherr, H. & Vancso, G.J., Closed Mechanoelectrochemical Cycles of Inidividual Single-Chain Macromolecular Motors by AFM, Angewandte Chemie, International Edition in English 46 (2007) 4800-8404. Vancso, G.J., Feeling the Force of Supramolecular Bonds in Polymers, Angewandte Chemie, International Edition in English 46 (2007) 3794-3796. Chang, T., Rozkiewicz, D.I., Ravoo, B.J., Meijer, E.W., & Reinhoudt, D.N., Directional movement of dendritic marcomolecules on gradient surfaces, Nano letters 7 (2007) 978-980. Delft, K.M. van, Eijkel, J.C.T., Mijatovic, D., Druzhinina, T., Rathgen, H., Tas, N.R., Berg, A. van den & Mugele, F., Micromachined Fabry-Perot interferometer with embedded nanochannels for nanoscale fluid dynamics, Nano letters 7(2) (2007) 345-350. Manen, H.J. van & Otto, C., Hybrid confocal Raman fluorescence microscopy on single cells using semiconductor quantum dots, Nano letters 7(6) (2007) 1631-1636. Taminiau, T.H., Moerland, R.J., Segerink, F.B., Kuipers, L. & Hulst, N.F. van, λ/4 Resonance of an Optical Monopole Antenna Probed by Single Molecule Fluorescence, Nano letters 1(1) (2007) 28-33. Troeman, A.G.P., Derking, J.H., Borger, B.C., Pleikies, J., Veldhuis, D. & Hilgenkamp, H., NanoSQUIDs Based on Niobium Constrictions, Nano letters 7 (2007) 2152-5256. Ymeti, A., Greve, J., Lambeck, P.V., Wink, T., Novell, S.W.F.M. van, Beumer, T.A.M., Wijn, R.R., Heideman, R.G., Subramaniam, V. & Kanger, J.S., Fast, ultrasensitive virus detection using a young interferometer sensor, Nano letters 7(2) (2007) 394-397. Nijhuis, C.A., Ravoo, B.J., Huskens, J. & Reinhoudt, D.N., Electrochemically controlled supramolecular systems, Coordination Chemistry Reviews 251 (2007) 1761-1780. Benetti, E.M., Zapotoczny, S.J. & Vancso, G.J., Tunable Thermoresponsive Polymeric Platforms on Gold by Photoiniferter-Based Surface Grafting, Advanced materials 19 (2007) 268-271.
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Feng, C.L., Embrechts, A., Bredebusch, I., Schnekenburger, J., Domschke, W., Vancso, G.J. & Schönherr, H., Reactive Microcontact Printing on Block Copolymer Films: Exploiting Chemistry in Microcontacts for Sub-µm Patterning of Biomolecules, Advanced materials 19 (2007) 286-290. Cacciapaglia, R., Casnati, A., Mandolini, L., Peracchi, A., Reinhoudt, D.N., Salvio, R., Sartori, A. & Ungaro, R., Efficient and selective cleavage of RNA oligonucleotides by calix[4] arenebased synthetic metallonucleases, Journal of the American Chemical Society 129 (2007) 12512-12520. Lokate, A.M.C., Beusink, J.B., Besselink, G.A.J., Pruijn, G.J.M. & Schasfoort, R.B.M., Biomolecular Interaction Monitoring of Autoantibodies by Scanning Surface Plasmon Resonance Microarray Imaging, Journal of the American Chemical Society 129(45) (2007) 14013-14018. Reynolds, N., Janusz, S., Escalante, M., Timney, J., Ducker, R.E., Olsen, J.D., Otto, C., Subramaniam, V., Leggett, G.J. & Hunter, C.N., Directed formation of micro- and nanoscale patterns of functional light-harvesting LH2 complexes, Journal of the American Chemical Society 129(47) (2007) 14625-14631. Rozkiewicz, D.I., Brugman, W., Kerkhoven, R.M., Ravoo, B.J. & Reinhoudt, D.N., Dendrimermediated transfer printing of DNA and RNA mircoarrays, Journal of the American Chemical Society 129 (2007) 11593-11599. Xu, W., Dong, M., Vazquez Campos, M.S., Gersen, H., Laegsgaard, E., Stensgaard, I., Crego Calama, M., Reinhoudt, D.N., Linderoth, T.R. & Besenbacher, F., Enhanced stability of large molecules vacuumsublimated onto AU(111) achieved by incorporation of coordinated AU-atoms, Journal of the American Chemical Society 129 (2007) 10624-10625. Ahlers, G., Fontenele Araujo Jr., F., Funfschilling, D., Grossmann, S. & Lohse, D., Non-OberbeckBoussinesq Effects in Gaseous Rayleigh-Bénard Convection, Physical review letters 98(5) (2007) 054501-1-051501-4. Asano, Y., Tanaka, Y. & Golubov, A., Josephson Effect due to Odd-Frequency Pairts in Diffusive Half Metals, Physical review letters 98 (2007) 107002. Asano, Y., Tanaka, Y., Golubov, A. & Kashiwaya, S., Conductance Spectroscopy of Spin-Triplet Superconductors., Physical review letters 99 (2007) 067005. Berg, Th.H. van den, Gils, P.M. van, Lathrop, D.P. & Lohse, D., Bubbly Turbulent Drag Reduction is a Boundary Layer Effect, Physical review letters 98 (2007) 084501-1-084501-4. Betouras, J.J., Giovannetti, G. & Brink, J. van den, Multiferroicity induced by dislocated spindensity waves, Physical review letters 98 (2007) 257602-1-257602-4. Borkent, B.M., Dammer, S.M., Schönherr, H., Vancso, G.J. & Lohse, D., Superstability of Surface Nanobubbles, Physical review letters 98 (2007) 204502-1-204502-4. Caballero Robledo, G.A., Bergmann, R.P.H.M., Meer, R.M. van der, Prosperetti, A. & Lohse, D., Role of Air in Granular Jet Formation, Physical review letters 99 (2007) 018001-1-018001-4. Hatami, M., Bauer, G.E.W., Zhang, Q.F. & Kelly, P.J., Thermal spin-transfer torque in magnetoelectronic devices, Physical review letters 99 (2007) 066603-1-066603-4. Jansen, R. & Min, B.C., Detection of a Spin Accumulation in Nondegenerate Semiconductors, Physical review letters 99 (2007) 246604-246604. Karpan, V.M., Giovannetti, G., Khomyakov, P.A., Talanana, M., Starikov, A.A., Zwierzycki, M., Brink, J. van den, Brocks, G. & Kelly, P.J., Graphite and graphene as perfect spin filters, Physical review letters 99 (2007) 176602-1-176602-4. Molen, K.L. van der, Tjerkstra, R.W., Mosk, A.P. & Lagendijk, A., Spatial Extent of Random Laser Modes, Physical review letters 98(143901) (2007) 1-4. Park, B.G., Banerjee, T., Lodder, J.C. & Jansen, R., Tunnel spin polarization versus energy for clean and doped Al2O3 barriers, Physical review letters 99 (2007) 217206-217206. Rathgen, H., Sugiyama, K., Ohl, C.D., Lohse, D. & Mugele, F., Nanometer-resolved collective micromeniscus oscillations through optical diffraction, Physical review letters 99 (2007) 99.214501. Savels, T., Mosk, A.P. & Lagendijk, A., Gain narrowing in few-atom systems, Physical review letters 98(103601) (2007) 1-4. Sbragaglia, M., Peters, A.M., Pirat, C., Borkent, B.M., Lammertink, R.G.H., Wessling, M. & Lohse, D., Spontaneous Breakdown of Superhydrophobicity, Physical review letters 99 (2007)
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Sbragaglia, M. & Prosperetti, A., Effective velocity boundary condition at a mixed slip surface, Journal of fluid mechanics 578 (2007) 435-451. Jong, N. de, Emmer, M., Ting Chin, C., Bouakaz, A., Mastik, F., Lohse, D. & Versluis, M., Compression-only behavior of phospholipid-coated contrast bubbles, Ultrasound in medicine and biology 33(4) (2007) 653-656. Hoekstra, H.J.W.M., Stoffer, R. & Yudistira, D., Strong control and squeezing effects of radiation states in a slab waveguide sandwiched between two omnidirectional mirrors, Journal of the Optical Society of America B (Optical physics) 24(4) (2007) 1004-1011. Wel, A.P. van der, Klumperink, E.A.M., Kolhatkar, J.S., Hoekstra, E., Snoeij, M.F., Salm, C., Wallinga, H. & Nauta, B., Low-frequency noise phenomena in switched MOSFETs, IEEE journal of solid-state circuits 42(3) (2007) 540-550. Liesener, A., Perchuc, A.M., Schoni, R., Schebb, N.H., Wilmer, M. & Karst, U., Screening of acetylcholinesterase inhibitors in snake venom by electrospray mass spectrometry, Pure and applied chemistry 79(12) (2007) 2339-2349. Sturm, J.M., Croes, G.O., Wormeester, H. & Poelsema, B., Metastable precursor for oxygen dissociation on Si(001) 2x1 resolved by high lateral resolution work function measurements, Surface science 601 (2007) 2498-2507. Sturm, J.M., Wormeester, H. & Poelsema, B., Heterogeneous oxidation of Si(111) 7 x 7 monitored with Kelvin Probe Force Microscopy, Surface science 601 (2007) 4598-4602. Vazquez-Campos, S., Crego Calama, M., Reinhoudt, D.N. & Reinhoudt, D.N., Supramolecular chirality of hydrogen-bonded rosette assemblies, Supramolecular chemistry 19 (2007) 95-106. Eshuis, P.G., Weele, J.P. van der, Meer, R.M. van der, Bos, R.J. & Lohse, D., Phase diagram of vertically shaken ganular matter, Physics of fluids 19 (2007) 123301-1-123301-11. Sbragaglia, M. & Prosperetti, A., A note on the effective slip properties for microchannel flows with ultrahydrophobic surfaces, Physics of fluids 19 (2007) 043603-1-043603-8. Versluis, M., Blom, C., Meer, R.M. van der, Weele, J.P. van der & Lohse, D., Leaping shampoo, Physics of fluids 19 (2007) 091106-091106. Huisstede, J.H.G., Subramaniam, V. & Bennink, M.L., Combining optical tweezers and scanning probe microscopy to study DNA-protein interactions, Microscopy research and technique 70(1) (2007) 26-33. Cacciapaglia, R., Casnati, A., Mandolini, L., Reinhoudt, D.N., Salvio, R., Sartori, A. & Ungaro, R., Di- and trinuclear arrangements of zinc(II)-1,5,9-triazacyclododecane units on the calix[4]arene scaffold: efficiency and substrate selectivity in the catalysis of ester cleavage, Inorganica chimica acta 360 (2007) 981-986. Kia, R., Mirkhani, V., Harkema, S. & Hummel, G.J. van, Synthesis and characterization of the 1:1 adducts of copper(I) halides with bidentate N,N′-bis(benzophenone)-1,2-diiminoethane Schiff base: Crystal structures of [Cu(bz2en)2][CuX2] (X = Br, I) complexes, Inorganica chimica acta 360 (2007) 3369-3375. Sbragaglia, M. & Sugiyama, K., Boundary induced nonlinearities at small Reynolds numbers, Physica D 228(2) (2007) 140-147. Spijksma, G.I., Kloo, L., Bouwmeester, H.J.M., Blank, D.H.A. & Kessler, V.G., Nonacoordinated MO6N3 centers M = Zr, Hf as a stable building block for the construction of heterometallic alkoxide precursors, Inorganica chimica acta 360 (2007) 2045-2055. Hussein, M.G., Worhoff, K., Sengo, G. & Driessen, A., Optimization of plasma-enhanced chemical vapor deposition silicon oxynitride layers for integrated optics applications, Thin solid films 515(7-8) (2007) 3779-3786. Geerken, M.J., Lammertink, R.G.H. & Wessling, M., Tailoring surface properties for controlling droplet formation at microsieve membranes, Colloids and surfaces A Physicochemical and engineering aspects 292 (2007) 224-235. Taminiau, T.H., Segerink, F.B., Moerland, R.J., Kuipers, L. & Hulst, N.F. van, Near-field driving of a optical monopole antenna, Journal of optics A : pure and applied optics 9 (2007) S315-S321.
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Chinthaginjala, J.K., Seshan, K. & Lefferts, L., Preparation and Application of Carbon-Nanofiber Based Microstructured Materials as Catalyst Supports, Industrial and engineering chemistry research 46(12) (2007) 3968-3978. Lüttge, R., Wolferen, H.A.G.M. van & Abelmann, L., Laser interferometric nanolithography using a new positive chemical amplified resist, Journal of vacuum science and technology B: microelectronics, processing and phenomena 25(6) (2007) 2476-2480. Tiggelaar, R.M., Berenschot, J.W., Elwenspoek, M.C., Gardeniers, J.G.E., Dorsman, R. & Kleijn, C.R., Spreading of thin-film metal patterns deposited on non-planar surfaces using a shadow mask micromachined in Si (110), Journal of vacuum science and technology B: microelectronics, processing and phenomena 25(4) (2007) 1207-1216. Tiggelaar, R.M., Benito-Lopez, F., Hermes, D.C., Rathgen, H., Egberink, R.J.M., Mugele, F., Reinhoudt, D.N., Berg, A. van den, Verboom, W. & Gardeniers, J.G.E., Fabrication, mechanical testing and application of high-pressure glass microreactor chips, Chemical engineering journal 131 (2007) 163-170. Ran, S., Winnubst, A.J.A., Koster, H., Veen, P. de & Blank, D.H.A., Sintering behaviour and microstructure of 3Y-TZP + 8 mol% CuO nano-powder composite, Journal of the European Ceramic Society 27(2-3) (2007) 683-687. Basabe desmonts, M.L., Baan, F.H. van der, Zimmerman, R.S., Reinhoudt, D.N. & Crego Calama, M., Cross-Reactive Sensor Array for Metal Ion Sensing Based on Fluorescent SAMs., Sensors 7 (2007) 1731-1746. Boogaard, A., Kovalgin, A.Y., Brunets, I., Aarnink, A.A.I., Holleman, J., Wolters, R.A.M. & Schmitz, J., Characterization of SiO2 films deposited at low temperature by means of remote ICPECVD, Surface and coatings technology 201 (2007) 8976-8980. Brunets, I., Aarnink, A.A.I., Boogaard, A., Kovalgin, A.Y., Wolters, R.A.M., Holleman, J. & Schmitz, J., Low-temperature LPCVD of Si nanocrystals from disilane and trisilane 3 (Silcore®) embedded in ALD-alumina for non-volatile memory devices, Surface and coatings technology 201 (2007) 9209-9214. Kovalgin, A.Y., Boogaard, A., Brunets, I., Holleman, J. & Schmitz, J., Chemical modeling of a high-density inductively-coupled plasma reactor containing silane, Surface and coatings technology 201 (2007) 8849-8853. Hallbäck, A.S.V.M., Poelsema, B. & Zandvliet, H.J.W., Rectification behaviour of molecular layers on Si(111), Solid state communications 141(12) (2007) 645-648. Bakker, G., Ploeg, M.J. van der, Rooij, G.H. de, Hoogendam, C.W., Gooren, H.P.A., Huiskes, C., Koopal, L.K. & Kruidhof, H., New Polymer Tensiometers: Measuring Matric Pressures Down to the Wilting Point, Vadose zone journal 6(1) (2007) 196-202. Fanciulli, R., Cerjak, I. & Herek, J.L., Low-noise rotating sample holder for ultrafast transient spectroscopy at cryogenic temperatures, Review of scientific instruments 78(5) (2007) 053102:1-5. Driessen, A., Geuzebroek, D.H., Klein, E.J., Dekker, R., Stoffer, R. & Bornholdt, C., Propagation of short lightpulses in microring resonators: Ballistic transport versus interference in the frequency domain, Optics communications 270(2) (2007) 217-224. Molen, K.L. van der, Mosk, A.P. & Lagendijk, A., Quantitative analysis of several random lasers, Optics communications 278 (2007) 110-113. Taminiau, T.H., Segerink, F.B. & Hulst, N.F. van, A Monopole Antenna at Optical Frequencies: Single-Molecule Near-Field Measurements, IEEE transactions on antennas and propagation 55(11) (2007) 3010-3017. Fuente Valentin, M.I. de la, Slot, P.J.M. van der & Boller, K.J., Liner radius fluctuations in a high-gain Cherenkov free-electron laser, Physical review special topics 10 (2007) 020702-1-020702-7. Khachatryan, A.G., Irman, A., Goor, F.A. van & Boller, K.J., Femtosecond electron-bunch dynamics in laser wakefields and vacuum, Physical Review Special Topics - Accelerators and Beams 10 (2007) 121301-1-121301-13. Biferale, L., Benzi, R., Sbragaglia, M., Succi, S. & Toschi, F., Wetting/dewetting transition of twophase flows in nano-corrugated channels, Computer-Aided Materials Design (2007) 447-456.
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Kawabata, S., Kashiwaya, S., Asano, Y., Tanaka, Y., Kato, T. & Golubov, A., Theory of macroscopic quantum tunnelling and dissipation in high-Tc Josephson junctions, Superconductor science and technology 20 (2007) S6. Borca, C.N., Apostolopoulos, V., Gardillou, F., Limberger, H.G., Pollnau, M. & Salathe, R.P., Buried channel waveguides in Yb-doped KY(WO4)2 crystals fabricated by femtosecond laser irradiation, Applied surface science 253(19) (2007) 8300-8303. Hallbäck, A.S.V.M., Poelsema, B. & Zandvliet, H.J.W., Negative differential resistance of TEMPO molecules on Si(111), Applied surface science 253(8) (2007) 4066-4071. Song, J., Gunst, U., Arlinghaus, H.F. & Vancso, G.J., Flame Treatment of Low-Density Polyethylene: Surface Chemistry Across the Length Scale, Applied surface science 253 (2007) 9489-9499. Arora, M., Ohl, C.D. & Lohse, D., Effect of nuclei concentration on cavitation cluster dynamics., Journal of the Acoustical Society of America 121(6) (2007) 3432-3436. Borkent, B.M., Arora, M. & Ohl, C.D., Reproducible cavitation activity in water-particle suspensions, Journal of the Acoustical Society of America 121 (2007) 1406-1412. Honschoten, J.W. van, Yntema, D.R., Svetovoy, V., Dijkstra, M., Wiegerink, R.J. & Elwenspoek, M.C., Analysis of the performance of a particle velocity sensor between two cylindrical obstructions, Journal of the Acoustical Society of America 121(5) (2007) 1-12. Meer, S.M. van der, Dollet, B., Voormolen, M.M., Chin, C.T., Bouakaz, A., Jong, N. de, Versluis, M. & Lohse, D., Microbubble spectroscopy of ultrasound contrast agents, Journal of the Acoustical Society of America 121(1) (2007) 648-656. Ma, Y., Hempenius, M.A. & Vancso, G.J., Electrostatic Assembly with Poly(ferrocenylsilanes), Journal of inorganic and organometallic polymers and materials 17 (2007) 3-18. Bystrova, S., Luttge, R. & Berg, A. van den, Study of crack formation in high-aspect ratio SU-8 structures on silicon, Microelectronic engineering 84 (2007) 1113-1116. Ran, S., Winnubst, A.J.A., Blank, D.H.A., Pasaribu, H.R., Sloetjes, J.W. & Schipper, D.J., Effect of Microstructure on the Tribological and Mechanical Properties of CuO-Doped 3Y-TZP Ceramics, Journal of the American Ceramic Society 90(9) (2007) 2747-2752. Robinson, D.K.R., Ruivenkamp, M. & Rip, A., Tracking the evolution of new and emerging S&T via statement-linkages: Vision assessment in molecular machines, Scientometrics 70(3) (2007) 831-858. Robinson, D.K.R., Rip, A. & Mangematin, V., Technological agglomeration and the emergence of clusters and networks in nanotechnology, Research policy 36 (2007) 871-879. Sarmany, D., Botchev, M.A. & Vegt, J.J.W. van der, Dispersion and dissipation error in highorder Runge-Kutta discontinuous Galerkin discretisations of the Maxwell equations, Journal of scientific computing 33(1) (2007) 47-74. Iannuzzi, D., Heeck, K., Slaman, M., De Man, S., Rector, J.H., Schreuders, H., Berenschot, J.W., Gadgil, V.J., Sanders, R.G.P., Elwenspoek, M.C. & Deladi, S., Fibre-top cantilevers: design, fabrication and applications, Measurement science and technology 18(10) (2007) 3247-3252. Pollnau, M., Grivas, C., Laversenne, L., Wilkingson, J.S., Eason, R.W. & Shepherd, D.P., TiSapphire waveguide lasers, Laser physics letters 4(8) (2007) 560-571. Iskandar, A.A., Yonan, W., Tjia, M.O., Voorde, I. van de & Groesen, E. van, Effective medium formulation for band structure design of a finite one-dimensional optical grating, Japanese journal of applied physics 46(1) (2007) 187-193. Thang, P.D., Rijnders, A.J.H.M. & Blank, D.H.A., Stress induced magnetic anisotropy of CoFe2O4 thin films using pulsed laser deposition, Journal of magnetism and magnetic materials 310 (2007) 2621-2623. Blanco Carballo, V.M., Chefdeville, M.A., Colas, P., Giomataris, Y., Graaf, H. van der, Gromov, V., Hartjes, F., Kluit, R., Koffeman, E., Salm, C., Schmitz, J., Smits, S.M., Timmermans, J. & Visschers, J.L., Charge amplitude distribution of the Gossip gaseous pixel detector, Nuclear instruments and methods in physics research Section A, Accelerators, spectrometers, detectors and associated equipment Volume 583(issue 1) (2007) 42-48.
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Blanco Carballo, V.M., Salm, C., Smits, S.M., Schmitz, J., Chefdeville, M.A., Graaf, H. van der, Timmermans, J. & Visschers, J.L., On the geometrical design of integrated micromegas detectors, Nuclear instruments and methods in physics research Section A, Accelerators, spectrometers, detectors and associated equipment 576(1) (2007) 1-4. Schmitz, J., Adding functionality to microchips by wafer post-processing, Nuclear instruments and methods in physics research Section A, Accelerators, spectrometers, detectors and associated equipment 576(1) (2007) 142-149. Visschers, J.L., Blanco Carballo, V.M., Chefdeville, M.A., Colas, P., Graaf, H. van der, Schmitz, J., Smits, S.M. & Timmermans, J., Direct readout of gaseous detectors with tiled CMOS circuits, Nuclear instruments and methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment 572 (2007) 203-204. Kovalgin, A.Y., Holleman, J. & Iordache, G., A pillar-shaped antifuse-based silicon chemical sensor and actuator, IEEE sensors journal 7(1) (2007) 18-27. Beulen, B., Jong, J. de, Reinten, H., Berg, M. van den, Wijshoff, H. & Dongen, R. van, Flows on the nozzle plate of an inkjet printhead, Experiments in fluids 42 (2007) 217-224. Golubov, A., Tanaka, Y., Kashiwaya, S. & Ueda, M., Ubiquitous presence of 0dd-frequency pairing state in superconducting junctions, Physica E 40 (2007) 163. Kawabata, S. & Golubov, A., Macroscopic quantum tunneling in Josephson pi-junctions with insulating ferromagnets and its application to phase qubits, Physica E 40 (2007) 386. Prosyentsov, V. & Lagendijk, A., The local density of states in finite size photonic structures, small particles approach, Photonics and nanostructures 5 (2007) 189-199. Jong, J. de, Geerken, M.J., Lammertink, R.G.H. & Wessling, M., Porous Microfluidic Devices Fabrication adn Applications, Chemical engineering and technology 30(3) (2007) 309-315. Segers-Nolten, G.M.J., Werf, K.O. van der, Raaij, M.E. van & Subramaniam, V., Quantitative Characterization of Protein Nanostructures Using Atomic Force Microscopy, IEEE EMBS SuB06.1 (2007) 6608-6611. Groenland, J.P.J. & Abelmann, L., Two-dimensional coding for probe recording on magnetic patterned media, IEEE transactions on magnetics 43(6) (2007) 2307-2309. Mitsuzuka, K., Kikuchi, N., Shimatsu, T., Kitakami, O., Aoi, H., Muraoka, H. & Lodder, J.C., Switching field and thermal stability of CoPt/Ru dot arrays with various thicknesses, IEEE transactions on magnetics 43(6) (2007) 2160-2162. Pollnau, M. & Romanyuk, Y.E., Optical waveguides in laser crystals, Comptes rendus physique 8(2) (2007) 123-137. Zhang, L., Bain, J.A., Zhu, J.G., Abelmann, L. & Onoue, T., The role of MFM signal in mark size measurement in probe-based magnetic recording on CoNi/Pt multilayers, Physica B 387(1-2) (2007) 328-332. Zandvliet, H.J.W., Saedi, A. & Hoede, C., The Anisotropic 3D Ising model, Phase transitions 80(9) (2007) 981-986. Salm, C., Hoekstra, E., Kolhatkar, J.S., Hof, A.J., Wallinga, H. & Schmitz, J., Low-frequency noise in hot-carrier degraded nMOSFETs, Microelectronics reliability 47(4-5) (2007) 577-580. Eijkel, C.J.M., Groen, A.J. & Walsh, S., Introduction to the section “Nanotechnology Policy�, Technological forecasting and social change 74(9) (2007) 1631-1633. Asano, Y., Tanaka, Y. & Golubov, A., Josephson current through a diffusive half metal., Physica C 463-465 (2007) 19. Brinkman, A. & Rowell, J.M., MgB2 tunnel junctions and SQUIDs, Physica C 456 (2007) 188. Kawabata, S., Golubov, A., Ariando, A., Verwijs, C.J.M. & Hilgenkamp, H., Theory of macroscopic quantum tunneling in Nb/Au/YBCO Josephson junctions, Physica C 460 (2007) 1479. Kawabata, S., Golubov, A., Tanaka, Y. & Kashiwaya, S., Quantum dissipative dynamics in nanostructure d-wave Josephson junctions, Physica C 463-465 (2007) 80. Mazin, I.I., Boeri, L., Dolgov, O.V., Golubov, A., Bachelet, G.B., Giantomassi, M. & Andersen, O.K., Unresolved problems in superconductivity of CaC6, Physica C 460 (2007) 116. Pleikies, J., Usenko, O., Kuit, K.H., Flokstra, J., Waard, A. de & Frossati, G., SQUID developments for the gravitational wave antenna MiniGRAIL, IEEE transactions on applied superconductivity 17 (2007) 764-767.
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Ortlepp, T., Ariando, A., Mielke, O., Verwijs, C.J.M., Foo, K., Andreski, A., Rogalla, H., Uhlmann, H. & Hilgenkamp, H., RSFQ Circuitry Using Intrinsic pi-Phase shifts, IEEE transactions on applied superconductivity 17(2) (2007) 659. Alvarez-Chavez, J.A., Martinez-Rios, A., Torres-Gomez, I. & Offerhaus, H.L., Wide wavelengthtuning of a double-clad Yb3+-doped fiber laser based on a fiber bragg grating array., Laser physics 4 (2007). 1-4. Rogalla, H., Fluxonics and Superconducting Electronics in Europe (invited paper), IEICE transactions on electronics E91-C(3) (2007). Boogaard, A., Kovalgin, A.Y., Brunets, I., Aarnink, A.A.I., Wolters, R.A.M., Holleman, J. & Schmitz, J., On the verification of EEDFs in plasmas with silane using optical emission spectroscopy, ECS Transactions 6(1) (2007) 259-270. Catalan, G., Vlooswijk, A.H.G., Janssens, J.A., Rispens, G., Redfern, S., Rijnders, A.J.H.M., Blank, D.H.A. & Noheda, B., X-ray diffraction of ferroelectric nanodomains in PBTIO3 thin films, Integrated ferroelectrics 92 (2007) 18-29. Steege, W.F. ter, Herber, S., Olthuis, W., Bergveld, P., Berg, A. van den & Kolkman, J., Assessment of a new prototype hydrogel CO2 sensor; comparison with air tonometry, Journal of clinical monitoring and computing 21(2) (2007) 83-90. Rozkiewicz, D.I., Gierlich, L., Burley, G.A., Gutsmiedl, K., Carell, T., Ravoo, B.J. & Reinhoudt, D.N., Transfer printing of DNA by “click” chemistry, ChemBioChem 8 (2007) 1997-2002. Falcucci, G., Bella, G., Chiatti, G., Chibbaro, S., Sbragaglia, M. & Succi, S., Lattice Boltzmann models with mid-range interactions, Communications in computational physics 2(6) (2007) 1071-1084. Febre, A.J. le, Luttge, R., Abelmann, L. & Lodder, J.C., Field emission to control tip-sample distance in magnetic probe recording, Journal of physics Conference series 61(1) (2007) 673-677. Manen, H.J. van, Apeldoorn, A.A. van, Verrijk, R., Blitterswijk, C.A. van & Otto, C., Intracellular degradation of microspheres based on cross-linked dextan hydrogels or amphiphilic Block copolymers: a comparative Raman microscopy study, Journal of Nanomedicine 2 (2007) 241-252. Phang In Yee, I., Aldred, N., Clare, A.S. & Vancso, G.J., Development of Effective Marine Antifouling Coatings, Studying Barnacle Cyprid Adhesion with Atomic Force Microscopy, NanoS 1 (2007) 34-39. Riele, P.M. te, Janssens, J.A., Rijnders, A.J.H.M. & Blank, D.H.A., Direct patterning of complex oxides by pulsed laser deposition through stencils, Journal of physics Conference series 59 (2007) 404-407.
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MONOGRAPHY – EDITORIAL BOOK Groesen, E. van & Molenaar, J. (2007). Continuum Modeling in the Physical Sciences (Mathematical Modeling and Computation, 13). SIAM.
BOOKS - CHAPTER Bauer, G.E.W., Tserkovnyak, Y., Brataas, A. & Kelly, P.J. (2007). Magnetic Nanostructures: Currents and Dynamics. In K.H.J. Buschow (Ed.), Handbook of Magnetic Materials (17) (p. 123-148). Amsterdam: Elsevier B.V.. Groenland, J.P.J. (2007). Magnetische registratie. In Poly-elektronica zakboek (p. D4_1-D4_1). Doetinchem: Reed Business bv. Kooij, E.S., Brouwer, E.A.M., Galca, A.C. & Poelsema, B. (2007). Field-assisted Nanocolloidal Selfassembly: Electrophoretic and Magnetopheretic Deposition. In Emilio A. Scarpetti (Ed.), Progress in Colloid and Surface Science Research (p. 11-12). New York, USA: NOVA Science Publishers, Inc., Hauppauge. Ludden, M.J.W., Crego Calama, M., Reinhoudt, D.N. & Huskens, J. (2007). Calixarenes on molecular printboards: multivalent binding, capsule formation, and surface patterning. In J. Vicens & J. Harrowfield (Eds.), Calixarenes in the Nanoworld (p. 213-231). Springer. Pollnau, M. (2007). Mid-Infrared lasers. In F. Trager (Ed.), Springer Handbook of Lasers and Optics (p. 660-674). New York, U.S.A.: Springer Science and Business media LLC. Thomson, T., Abelmann, L. & Groenland, J.P.J. (2007). Magnetic data storage: past, present and future. In B. Azzerboni, G. Asti, L. Pareti & M. Ghidini (Eds.), Magnetic Nanostructures in Modern Technology (NATO Science for Peace and Security Series Subseries: NATO Science for Peace and Security Series B: Physics and Biophysics) (p. 237-306). Berlin: Springer Verlag.
EDITORIAL BOOKS Boon, M. & Waelbers, K. (Eds.). (2007). Abstracts of the first biennial conference SPSP 2007. Enschede: University of Twente.
PATENTS Broekmaat, J.J., Roesthuis, F.J.G., Blank, D.H.A. & Rijnders, A.J.H.M. (18-10-2007). Scanning Probe Microscope. no PCT/EP2007/009168. Burdinski, D., Sharpe, R.B.A., Blees, M. & Huskens, J. (03-05-2007). A Method of Manufacturing a Structure. no WO2007049225. Janczewski, D., Tomczak, N., Khin, Y.W., Han, M. & Vancso, G.J. (02-04-2007). Versatile platform for coating, solublization and functionalization of nanoparticles. no RA-IDF-0407. Jurna, M., Otto, C. & Offerhaus, H.L. (15-05-2007). Verfahren und Vorrichtung zum Erzeugen eines nicht-linearen optischen Signals an einem durch ein Anregungsfeld angeregten Materials sowie Verwendung des Verfahrens und der Vorrichtung. no A274DE1. La Rosa, G., Vancso, G.J. & Meer, D.W. van der (26-06-2007). Polimeri della serie olefinica rinforzati con strutture transcristalline. no CT2007A000015. Peters, P.J.M., Mathew, D., Bastiaens, H.M.J. & Boller, K.J. (25-04-2007). Method and system for creating a homogeneous pulsed gas discharge. no 07106948.8. Rozkiewicz, D.I., Reinhoudt, D.N. & Mirkin, C.A (01-08-2007). Matrix assisted DPN of Biomolecules. no.
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Rozkiewicz, D.I., Ravoo, B.J. & Reinhoudt, D.N. (06-06-2007). Method of direct microcontact printing of a pattern on a substrate obtainable and the use of such substrate. no 05077749.8. Schlautmann, S., Berg, A. van den & Gardeniers, J.G.E. (13-12-2007). Method of fabrication of a microfluidic device. no US 2007/0286773. Schutte, H., Hempenius, M.A. & Vancso, G.J. (18-01-2007). Novel Monomeric and Polymeric Materials. no WO 2007/082919 A2.
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ABOUT MESA+
M E S A + G overnance S tr u ct u re MESA+ Governing Board Prof. dr. ir. A. Bliek Dean Faculty Science & Technology (till Nov. 2007) Dr. G.J. Jongerden Managing Director Helianthos BV Ir. J.J.M. Mulderink Consultant Sustainable Technology Dr. A.J. Nijman Director Research Strategy & Business Development Philips NatLab Prof. dr. J.A. Put Director Performance Materials DSM Research Prof. dr. ing. M. Wessling Interim dean Faculty Science & Technology (from Nov. 2007) Ir. M. Westermann President of GigaPort Next Generation Network (till July 2007) Prof. dr. ir. A.J. Mouthaan Dean Faculty of Electrical Engineering, Mathematics and Computer Science
MESA+ Scientific Advisory Board Dr. J.G. Bednorz IBM Zürich Research Laboratory, Switzerland Prof. H. Fujita University of Tokyo, Japan Prof. M. Möller Rheinisch-Westfälische Technische Hochschule Aachen (RWTH), Germany Prof. C.N.R. Rao Jawaharlal Nehru Centre for Advanced Scientific Research, India Dr. H. Rohrer IBM Zürich Research Laboratory, Switzerland Prof. F. Stoddart University of California, USA Prof. E. Thomas Massachusetts Institute of Technology (MIT), USA Prof. E. Vittoz Swiss Center for Electronics and Microtechnology (CSEM), Switzerland Prof. G. Whitesides Harvard University, USA
MESA+ Management Prof. dr. ing. D.H.A. Blank Ir. M. Luizink
Scientific Director Technical Commercial Director
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C O N TA C T D E TA I L S MESA+ Institute for Nanotechnology University of Twente P.O. Box 217 7500 AE Enschede, Netherlands Tel.: + 31 53 489 2715 E-mail: info@mesaplus.utwente.nl www.mesaplus.utwente.nl
Colophon Editing: MESA+ Institute for Nanotechnology Miriam Luizink, Annerie van Steijn-Heesink Design: Zone2design Communication Department, Olaf Stokkers
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