CDE Forging New Frontiers
Issue 02 | Jul 2024
Dear Reader,
Welcome to the latest edition of the CDE Research Newsletter — Forging New Frontiers!
The theme of this issue is From Idea to Reality.
At the foundation of this issue is a series of breakthroughs at CDE that form the impetus of real-world technical impact and serve as catalysts towards societal and policy impact. Importantly, these innovations showcase the diversity of fields where our CDE community are driving change, from energy and sustainability to sensors and biomedicine.
Examples of our pioneering featured work include a study led by Associate Professor Jimmy Peng (Electrical and Computer Engineering) that proposes a framework for electric vehicle (EV) charging infrastructure to increase accessibility while helping policymakers in planning strategy.
Research by Associate Professor Zhao Dan (Chemical and Biomolecular Engineering) and his team has realised porous crystal technology for highly sensitive and specific gas sensing, which spans chemical detection through atmospheric monitoring.
Assistant Professor Clement Zheng (Industrial Design) embedded interactive circuits into ceramic, taking an everyday material to new heights. This opens doors to everything from touch-sensitive plates to smart flowerpots!
In healthcare, Assistant Professor Eliza Fong (Biomedical Engineering) led research to pioneer the development of a hydrogel capable of markedly prolonging the use of cancer cells for drug testing, which could change how we personalise patient treatment.
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Taking a page from nature, Associate Professor Benjamin Tee (Materials Science and Engineering) and his team developed ‘eAir,’ a pressure sensor that provides vital feedback to doctors in scenarios such as surgical settings.
In a major step forward towards chip technologies for everything from smart buildings to wearables, Professor Massimo Alioto is serving as Director of the FD-fAbrICS (FD-SOI Always-on Intelligent & Connected Systems) joint lab, which is markedly enhancing the energy efficiency of chips that power AI devices.
In sum, this issue reveals a profoundly agile ecosystem at CDE that validates innovation and provides a clear path towards large-scale societal and policy impact. Our community is proud to be a cornerstone of bridging ideas with reality.
We hope you enjoy the issue!
All the best,
Dean Ho Editor-in-Chief
Supercharging the resilience of the EV ecosystem
Uncovering the impact of urban flooding on the accessibility of EV chargers paves the way for mitigation strategies that help policymakers strengthen the resilience of charging infrastructures.
The motors of the electric vehicle (EV) sector are spinning at full throttle — with the goal of eventually phasing out internal combustion engines that guzzle fossil fuels and emit planet-cooking gases. But the very lifeline that keeps the sector moving forward — its charging infrastructure — is beginning to experience significant strain.
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This strain could adversely impact the perceived availability and accessibility of charging stations, which in turn fuels range anxiety and dampens EV adoption. It is also crucial that the chargers are resistant to external factors, such as weatherrelated events.
Researchers from the College of Design and Engineering at the National University of Singapore have studied the impact of urban flooding on public EV charging networks, focusing on Greater London. Their research zooms in on how climate-induced flooding affects these networks, revealing significant stress and accessibility challenges for chargers during such events.
Their insights shine a crucial light on resilient infrastructure planning, offering strategic guidance for the private sector and policymakers alike in enhancing the flood resilience of urban EV charging networks. Led by Associate Professor Jimmy Chih-Hsien Peng from the Department of Electrical and Computer Engineering, the team’s findings were published in Nature Communications on 09 June 2022.
Going the extra mile
From New York to London to Singapore, urban flooding — increasingly frequent and severe due to climate change — has exposed charging infrastructure to the elements.
Floods pose risks to EV charging stations in two main ways. Firstly, individual chargers may go out of service due to water damage. On the other hand, even if chargers are weatherised or elevated, they can still become unusable if the surrounding parking areas are waterlogged.
The team’s research addresses a gap in existing literature, providing insights into disruptions that may occur if a significant number of chargers in a network are compromised by flooding.
Through computer simulations, fed with publicly available data on vehicle driving habits, the research team analysed changes in charging patterns during flooding events in Greater London. They also evaluated methods to enhance the resilience of the charging infrastructure.
Associate Professor Jimmy ChihHsien Peng’s research guides the deployment of resilient urban EV charging networks.
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“Greater London provided a particularly informative case study for several reasons,” explains Assoc Prof Peng. “The region has a significant share in the UK’s EV market, accounting for about a seventh of all sales, and is on a path to shift entirely to EVs by 2030. Moreover, a considerable area of Greater London is prone to flooding — many boroughs and key development areas are at high risk. This, combined with the fact that over 40% of drivers in the area depend on public or on-street parking — areas most vulnerable to such events — made it a compelling focus for our research into the resilience of charging infrastructure.”
“What is surprising is that this impact extends beyond the immediate flood areas, affecting regions up over 10 kilometres away as EV users are forced to postpone their charging.”
The team discovered that while flooding does not impede typical urban travel for EV drivers, it substantially stresses and limits access to parts of the charging network. “What is surprising is that this impact extends beyond the immediate flood areas, affecting regions up over 10 kilometres away as EV users are forced to postpone their charging,” says Gururaghav Raman, a Research Fellow and a former PhD student at NUS, who is also the first author of the study.
“These findings highlight the need for placing new chargers strategically, particularly in areas less prone to flooding, to alleviate the pressure on existing networks,” adds Raman.
Building future-proof charging infrastructure
The researchers have proposed four strategies for deploying new chargers. The first involves placing additional chargers just outside flood-affected areas — effectively ring-fencing these regions to destress nearby infrastructure. The second strategy is usage-dependent, where chargers are placed in areas with the highest baseline utilisation. The third, a distance-based approach, plants chargers near the most affected locations far from flood zones to reduce peak stresses. The final strategy involves randomly distributing new chargers throughout the network.
Through simulations, the team put their strategies to the test. Results have shown that the usage-dependent strategy excels in enhancing flood resilience, accessibility and efficiency of the charging network. In particular, just adding 5–10% more chargers could restore peak utilisation to baseline levels during floods. The researchers also point out that this strategy aligns with the competitive nature of the private sector, which installs most new public chargers.
Additionally, the researchers also highlighted the effectiveness of ring-fencing vulnerable areas around the Thames with additional chargers — irrespective of baseline demand — to reduce stress and improve accessibility. On the other hand, randomly placing chargers has its benefits too. “While these two strategies are not immediately profitable, government subsidies can play a crucial role in catalysing the installation of chargers in these areas, which bolsters accessibility and supercharges consumer confidence,” adds Raman.
“Augmenting these strategies depends on the availability of more detailed cityspecific data,” says Assoc Prof Peng, who is actively involved in planning and formulating industry standards. “For instance, if furnished with information on installation costs, revenue and flood risk, policymakers could employ multi-criteria optimisation methods to better determine the most effective locations for new chargers — catering to the unique needs and challenges of each city.”
Sniffing out gases with precision
Flexible, shape-shifting organic frameworks are capable of sensing gases with high precision for applications in adsorption, separation and storage.
The human nose, capable of sniffing out over a trillion scents, still struggles to identify tricky gas combinations, especially at specific levels of sensitivity. This is where sensors come in, as a concoction of carefully calibrated materials teases out the presence of trace gaseous molecules camouflaged within the atmosphere.
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Associate Professor Zhao Dan led a team to develop materials capable of sensing gases with high precision and specificity.
Sensors are to many industries today what the five senses are to us. They scour for harmful substances in drinking water, help capture greenhouse gases from industrial emissions, detect hazardous chemical leaks in factories, and even suck carbon dioxide out of thin air, among myriad other applications. Being able to discern gas molecules accurately offers a multitude of benefits, underscoring the importance of developing advanced sensor technology in modern industry.
At the College of Design and Engineering, National University of Singapore, a research team led by Associate Professor Zhao Dan from the Department of Chemical and Biomolecular Engineering has developed covalent organic frameworks (COFs) capable of separating and “sniffing out” certain gas molecules with precision. The material, which can be used in sensors, has versatile uses ranging from gas adsorption to separation to storage.
Their findings were published in Nature Materials on 10 April 2023.
Stability and flexibility are the mainstay
Soft/flexible porous crystals (SPCs), characterised by their spongy structure riddled with tiny pores, stand apart from their more rigid counterparts due to their unique ability to morph in response to environmental changes.
Because of their shape-shifting capability, SPCs have the potential to interact with a plethora of molecules dynamically. For instance, when exposed to different conditions, their pores can expand, contract, or change shape, dictating how surrounding molecules are adsorbed, filtered, or separated. This key feature positions these materials as prime
“Metal-organic frameworks (MOFs) are a commonly researched subset of SPCs in sensor technology, but their structural stability falls short for largescale industrial applications.”
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Forging New Frontiers
candidates for various applications, from smart filtration to controlled drug release to the separation and storage of gases.
“Metal-organic frameworks (MOFs) are a commonly researched subset of SPCs in sensor technology, but their structural stability falls short for large-scale industrial applications,” says Assoc Prof Zhao. “Meanwhile, COFs are emerging as highly stable alternatives, though they still lack the necessary flexibility to interact with different types of gas molecules.”
“Considering the increased complexity of today’s industrial processes and the diverse cocktails of gases involved, coupled with the urgency of the green transition, both stability and flexibility have become two indispensable features required for the advanced sensors of tomorrow,” adds Assoc Prof Zhao.
A rare arrangement
The team’s breakthrough solution came in the form of atropisomerism — a type of stereoisomerism characterised by a restricted rotation around a bond within a molecule, leading to distinct spatial arrangements of the atoms. This property is rare in crystals with infinite framework structures, such as those found in COFs, highlighting the novelty of their approach.
“We plan to broaden the range of COFbased atropisomers and enhance their capabilities by finetuning crystal growth conditions, topology, linkage flexibilities and chemical bonding.”
Based on this concept, they engineered two COF-based atropisomers, COF320 and COF-320-A. The latter was synthesised by reducing the temperature of the standard process through which COF-320 is normally prepared, from the usual 120 °C to 65 °C. This temperature change was key in limiting the movement of bonds and the monomers themselves, coaxing them into arrangements that eventually locked into metastable crystal structures — resulting in the distinct shape of COF-320-A.
It was this difference in the spatial arrangement of atoms in both COF variants — despite their identical chemical structures — that proved to be crucial.
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While COF-320 maintained a rigid framework, its isomeric counterpart was far more flexible, possessing the capability to adjust its pore structures in response to different gases, thus showcasing a diverse range of gas adsorption behaviours.
“Our experiments have shown that COF-320-A can undergo internal pore expansion, effectively capturing key industrial gases such as ethylene, carbon dioxide and acetylene,” adds Assoc Prof Zhao. “This adaptability not only enhances gas sensing accuracy but also opens up new applications in industrial gas separation and storage.”
With practical applications soon a reality, the researchers have their sights set on further optimising these COFs. “We plan to broaden the range of COF-based atropisomers and enhance their capabilities by fine-tuning crystal growth conditions, topology, linkage flexibilities and chemical bonding,” adds Assoc Prof Zhao. “COFs with high stability and dynamic frameworks can be widely applied in gas sensing, storage and separation.”
Serving innovation on a ceramic platter
Innovative ceramic wares with built-in electronic circuits are capable of responding to touch, temperature and moisture, blending technology with everyday items to create convenience and connection. Industrial Design
Sometimes, innovation hides in plain sight. Or in items you’d least expect. Such as the breakfast china used to hold scrambled eggs or the porcelain bowl cradling a comforting serving of ramen or the decorative vase brightening up a living room.
Issue 02 | July 2024
All these items share a common denominator: ceramic. It’s ubiquitous — yet often overlooked and underutilised. Assistant Professor Clement Zheng from the Division of Industrial Design (DID) at the College of Design and Engineering, National University of Singapore, sees untapped potential in glazed ceramics and has infused these common objects with his ingenious touch — by integrating electronic circuits to bring them to life.
Asst Prof Zheng’s research introduces a fresh approach to embedding interactive circuits into ceramics. By carving traces on the ceramic surfaces and filling them with conductive ink, his work has transformed everyday objects into human-computer interfaces and smart devices that can participate in daily activities — from touch-sensing tableware to temperature-sensitive tiles to moisture-aware flowerpots.
Forging New Frontiers
This approach was published in a paper presented at the 2023 CHI Conference on Human Factors in Computing Systems.
When craft and computing collide
In ‘ubiquitous computing’, computational technology disappears and weaves itself into the fabric of everyday life. This concept guided Asst Prof Zheng and his team as they explored the potential of interactive circuits on glazed ceramic ware. Drawing inspiration from smart textiles and touch-sensitive surfaces led to the eureka moment where they imagined a future in which everyday ceramic objects could be transformed into interactive interfaces.
Bringing together a unique blend of expertise, involving professional designers and builders of interactive systems, the multidisciplinary team “aimed to entangle the materiality of the investigated craft with the physical and computational materiality of tangible interfaces and interactive electronics.”
The process began with masking the ceramic surfaces using adhesive vinyl film cut into intricate patterns. Using an adaptation of resist-blasting, a technique developed by Associate Professor Hans Tan from DID, the team then sandblasted these masked surfaces to carve out the circuit traces on the surfaces. Once the masking was removed, the recessed areas formed the foundation for the circuits.
Assistant Professor Clement Zheng embedded interactive circuits into ceramic wares, transforming everyday objects into human-computer interfaces and smart devices.
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Forging New Frontiers
Next, they adorned these recessed traces with conductive inks, creating functional — and aesthetically pleasing — electronic traces. This meticulous process transformed ordinary ceramics into smart devices capable of sensing a range of parameters, from touch to temperature to moisture.
Applications galore
Integrating interactive circuits into glazed ceramics opens up a world of practical — and intriguing — applications. Take tableware, for instance. Like the bashful touch-me-not plant, plates and bowls embedded with circuits can respond to touch, controlling ambient music or lighting during meals, as part of an overarching smart-home system. Or imagine a colour-shifting plate that senses the temperature of the food it holds, adding a new dimension to culinary presentation.
Temperature-sensitive tiles can monitor the heat levels of kitchens and bathrooms in real-time, providing visual feedback and enhancing occupant safety. For instance, sensors on the back wall of a kitchen stove can indicate if a stove is in use, or if there is a fire. In the bathroom, sensors can point out if there is a leak, or if the floor is wet.
Smart ceramics can also cultivate better plant owners. Moisture-aware plant pots can monitor soil hydration levels and alert users when plants need watering — a clever blend of technology with gardening for improved plant care.
Reciprocating warmth and conviviality
The researchers’ smart ceramics also unlock new avenues for expression. One of Asst Prof Zheng’s creations, Reciproco, conceived together with independent designer and artist Genevieve Ang, was proudly showcased at Future Impact 2, an exhibition of new works by a select group of Singaporean designers who were commissioned by Design Singapore Council.
Reciproco comprises a pair of interactive ceramic pieces coated in glaze formulated with glass waste and enhanced with
“Reciproco is about presence and how materials and technology can support communication between two people.”
thermochromic paint. The piece changes colour when the surface is activated. It is also heated with circuits embedded into the ceramic body that are triggered when touched.
“If someone places their hand on one, the other — whether it’s across the room or on the other side of the world — will heat up in response,” says Asst Prof Zheng. “Reciproco is about presence and how materials and technology can support communication between two people.”
Crafting ceramics of the future
Asst Prof Zheng is keen on addressing larger infrastructural needs to integrate smart ceramics into homes. “For example, while acrylic placements were a clever way to connect ceramics to a microcontroller, everything has to be carefully placed so that the conductive pads align with the pins of the placemat,” adds Asst Prof Zheng.
This includes developing specialised hardware components and collaborating with interior designers, builders and electricians to explore how ceramic interfaces — and the required electronics infrastructure — can be threaded into living spaces more seamlessly. Additionally, other future work being considered includes developing new computational design algorithms and digital fabrication processes to further enhance interactive ceramic systems.
Biomedical Engineering
Keeping cancer cells content
A jelly-like hydrogel platform keeps tumours alive for ten days, enabling an effective testing ground for various anticancer drugs and treatments.
Like our fingerprints, no two cancers are alike. Each individual cancer — even those of the same type — carries a myriad of genetic nuances, and may therefore behave differently and respond to treatments in distinct ways.
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Recognising these subtleties has led to the advent of ‘personalised medicine’ in the medical lexicon. In this context, culturing fragments of a patient’s tumour can do wonders in pinpointing the most effective anti-cancer drugs for that particular individual. But once those cancer cells leave the body, a countdown begins. As clinical scientists race to decipher the molecular and cellular underpinnings during the drug testing process, they often struggle to outpace the rapid speed at which tumour tissue disintegrates.
Assistant Professor Eliza Fong from the Department of Biomedical Engineering at the College of Design and Engineering, National University of Singapore, has a trick up her sleeve to ‘freeze’ those cells in time — using hydrogels. Functioning as scaffolds, these hydrogels contain structures that can hold the composition and architecture of the tumour fragments in place for ten days — well beyond the two-day window typically afforded.
This extended preservation allows scientists more time to study the tumour, figure out what drugs work best and ultimately save time, resources — and most importantly — lives.
Their findings were published in Biomaterials on 2 January 2024.
Turning the tide on time-limited processes
Unravelling cancers for drug testing is complex — riddled with its complicated webs of diverse cells, interactions and mechanisms that need to be uncovered. Examining tumour samples ex vivo, outside the patient’s body, is one effective way to study the disease in a controlled environment. Compared to traditional cancer cell cultures and organoid models, it better preserves the tumour’s natural architecture and cellular interactions, providing a more accurate model for testing treatments.
Nevertheless, the short lifespan of such samples limits their viability, putting a damper on comprehensive drug testing. To extend the lifespan of tumour samples, Asst Prof Fong led a team to bioengineer a jelly-like hydrogel made of hyaluronic acid, a water-based, lubricating fluid found naturally in the eyes and joints — and commonly used in skincare products as a moisturiser.
Assistant Professor Eliza Fong led research to pioneer the development of a hydrogel capable of prolonging the use of cancer cells for drug testing.
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Using a vibrating microtome machine, the researchers shaved precise fragments of tumours taken from patients with head and neck cancers and cultivated them on the hydrogel.
“We found that various biophysical properties, such as stiffness, degradability and integrin adhesivity, of the hydrogel matrix play an important role in maintaining the viability, tissue integrity and composition of the tumour slices,” says Asst Prof Fong.
Forging New Frontiers
“We found that various biophysical properties, such as stiffness, degradability and integrin adhesivity, of the hydrogel matrix play an important role in maintaining the viability, tissue integrity and composition of the tumour slices.”
For instance, the stiffness of the matrix influences how well the cellular structures of the tumour are preserved. The hydrogel is also customisable to support the culturing of other cancers, such as such as peritoneal, lung, colorectal and ovarian. Samples from metastatic tumours, for instance, may require a hydrogel matrix that is less adhesive and more resilient to prevent cancer cells from invading and disrupting the matrix. On the other hand, matrices that are more porous can better facilitate the flow of nutrients and oxygen throughout the hydrogel, which in turn benefits tumours that are metabolically demanding and highly vascularised.
“This can pave the way for longer-lasting hydrogel platforms tailored to each patient’s distinct tumour profile,” says Asst Prof Fong. “Think of them as true patient avatars for personalised and precision oncology!”
Conserving cellular chatter
When cancer cells are tightly packed together in a tumour, they can ‘talk’ to one another. This chatter also extends to neighbouring supporting cells. While these communication pathways facilitate tumour development and spread, decoding and targeting this cellular language can help turn the tables — halting its growth and averting drug resistance.
The team’s hydrogel preserves cell-to-cell communication networks within the tumour microenvironment, including those integral to immunotherapy — a targeted approach that involves boosting the body’s immune system to identify, intercept and eradicate cancer cells.
“By maintaining the compositional heterogeneity of the original tumours, including various cell populations and their interactions, the hydrogel keeps crucial communication pathways intact,” says Asst Prof Fong. “This includes those related to immune checkpoint inhibitors (ICIs), a type of immunotherapy that puts the brakes on the cancer’s ability to evade the immune system, giving it a fighting chance to attack cancer cells more effectively.”
Co-clinical trial results have revealed that cancer cultures preserved in the hydrogel may indeed predict sensitivity to ICIs in head and neck cancer patients. “This is an exciting development as it suggests that our hydrogel can provide a more reliable method for evaluating patient-specific responses to immunotherapy, potentially leading to more individualised treatments.”
At the frontiers of cancer treatment
While promising, the researchers point out that there are still limitations in predicting immune responses in metastatic or recurrent tumours, which may differ from the original resected tumour.
Further research is underway to clinically validate how the team’s hydrogel responds in larger patient populations. The researchers also suggest exploring the inclusion of perfusion to preserve vasculature and the integration of tumour-draining lymph nodes to enhance the accuracy of ICI efficacy predictions — all of which could expand the applications of their groundbreaking hydrogel platform.
Learning from the lotus leaf
Inspired by the lotus leaf, the ‘eAir’ sensor achieves nearideal pressure sensing and is applicable in diverse liquid environments, including those involved in medical settings.
Being able to adapt to varying levels of pressure adeptly is a highly soughtafter trait. More so for pressure sensors.
Sensitive and reliable pressure sensors can help extend the human senses in many applications. In medicine, many devices now depend on accurate and stable pressure measurements to function reliably. From ensuring the optimal function of sleep apnea machines to delivering precise drug dosages through infusion pumps
Issue 02 | July 2024 Forging New Frontiers
or measuring in vivo blood pressure, pressure sensors underpin many healthcare applications — and better sensors translate to improved outcomes.
Drawing inspiration from the superhydrophobic nature of lotus leaves, a research team led by Associate Professor Benjamin Tee from the Department of Materials Science and Engineering at the College of Design and Engineering, National University of Singapore (NUS) and the NUS Institute for Health Innovation & Technology has developed a novel aero-elastic pressure sensor called ‘eAir’.
The team’s sensor enhances precision and reliability across medical applications, from enabling tactile feedback during laparoscopic surgeries to improving patient experiences by providing a less invasive means of monitoring intracranial pressure.
The team’s findings were published in the journal Nature Materials on 17 August 2023.
From lotus leaf to laboratory
Conventional pressure sensors, such as those relying on piezo-based, solid-state materials like polymers, are well-developed but often struggle with accuracy in water-based environments. Such sensors are also typically made from mechanically inflexible materials.
To craft sensitive, water-loving pressure sensors, the researchers took a leaf out of nature’s book — one that is attached to the lotus plant, which effortlessly sheds water and dirt despite calling murky ponds home. This uncanny ability is owed to micro- and nanostructures on the leaves’ surface, which trap a thin layer of air, minimising the contact area for water. This air layer is also highly sensitive to pressure.
Emulating the structures on a lotus leaf’s surface, the researchers adorned their novel sensing device with myriad microscopic, domed-tipped pillars — coated with silicone oil, organised in an array structure and housed in hexagon-walled chambers — all of which contribute to reducing the surface friction on the electrode to near zero.
“This ultra-slippery surface means that eAir is highly linear and very sensitive. It exhibits low hysteresis, which is the error in sensing between the applied pressure cycles,” says Assoc Prof Tee.
Associate Professor Benjamin Tee took a page from nature to develop ‘eAir’, a pressure sensor that provides vital feedback in medical settings.
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“It’s like a capacity meter, which can detect minute pressure changes — much like the sensitivity of a lotus leaf to the extremely light touch of a tiny water droplet.”
Forging New Frontiers
Like the lotus leaf, eAir’s ‘air spring’ design contains a trapped layer of air, forming an air-liquid interface upon contact with the sensor’s liquid. As external pressure increases, this air layer compresses. The near-friction-free microstructures allow the interface to glide along these surfaces, triggering changes in electrical signals that accurately reflect the applied pressure.
“It’s like a capacity meter, which can detect minute pressure changes — much like the sensitivity of a lotus leaf to the extremely light touch of a tiny water droplet,” adds Assoc Prof Tee.
See the technology in action here
A step-change in the operating theatre
eAir is capable of operating in turbulent liquids, as well as in in vivo biological environments, such as those encountered in laparoscopic procedures. The team has demonstrated its practical use in the in vivo monitoring of intracranial pressure in a rat model, with performance matching that of commercial sensors.
“Our sensor can also be readily integrated with tools that require tactile feedback, such as laparoscopic graspers, which could improve safety and precision in surgical procedures,” says Assoc Prof Tee.
The team envisions the eAir platform evolving into devices with simple, lowcost preparation processes. “Leveraging other solid or quasi-liquid super-slippery surfaces within the microstructures could lead to high-performance eAir sensors that are exceptionally stable,” adds Assoc Prof Tee. “We anticipate more use cases as we test these new approaches for long-term use — watch this space!”
Drawing inspiration from the ‘lotus leaf effect’, these golden strips, known as ‘eAir’ pressure sensors, promise high precision and stability, bringing transformative capabilities to applications in healthcare.
Turbocharging the energy efficiency of AI processors
Breakthroughs in chip design techniques offer three crucial benefits for AI devices: reduced power consumption, extended battery life and the ability to support intense computational workloads.
From the alarm on a smartphone that starts the day, to a home security system keeping a family safe, to the electronic control unit controlling the critical sub-systems of a vehicle, and the desktop computer driving office productivity, many facets of everyday life are interconnected by one crucial component: microchips, the brain cells of the digital age.
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Despite the ubiquity of silicon chips, there is no ‘one-chipfits-all’ solution. Consider smaller, low-power devices, such as those making up the expanding Internet-of-Things (IoT) universe. Energy-efficient chips are a mainstay for these applications. A smartwatch that can’t last a day without charging is a smartwatch won’t find a market. Sensors that fail to operate continuously would be a catalyst for catastrophe in modern factory settings.
This has placed energy efficiency at the front of mind for artificial intelligence (AI) chip manufacturers. At the College of Design and Engineering, National University of Singapore, Professor Massimo Alioto and his research team from the Department of Electrical and Computer Engineering have innovated a new class of silicon-based systems that gives the energy efficiency of AI-connected devices a significant boost. Developed in collaboration with industry partners Soitec and NXP Semiconductors, this technology has the potential to revolutionise the design of advanced semiconductor components in fully depleted silicon-oninsulator (FD-SOI).
“This new technology enables AI at the edge — where AI models and algorithms can be deployed directly on small devices such as sensors or IoT gadgets used in myriad applications, from smart buildings and Industry 4.0 to wearables and smart logistics,” says Prof Alioto, who is also the Director of the FD-fAbrICS (FD-SOI Alwayson Intelligent & Connected Systems) joint lab, where the invention transitioned from concept to reality. “This localisation means real-time data processing and analysis with much-reduced burden on network and cloud infrastructure to support the exponential growth of intelligent and connected devices.”
Energy efficiency is top of mind
IoT devices are increasingly infused with AI and machine learning capabilities to bring intelligence and autonomy to various systems and processes, such as autonomous driving, industrial smart manufacturing, medical equipment and home automation. Most of these devices are small, power- and cost-constrained microcontroller-based systems. On top of that, network bandwidth and consumer expectations around data privacy and user experience continue to drive more on-device processing — where data is processed directly on IoT devices rather than in the cloud.
Professor Massimo Alioto led a team to enhance the energy efficiency of chips that power AI devices.
“IoT devices often operate on a very limited power budget — requiring low average power to perform regular tasks such as physical signal monitoring in sensors,” says Prof Alioto. “Concurrently, they also need high peak performance to process occasional signal events using computationally intensive AI algorithms.”
The new tech developed by the NUS researchers kills three birds with one chip. Not only does it support serious number-crunching in such applications, but it also helps smart wearables save battery juice — by tenfold — and slashes the power consumption associated with wireless communications with the cloud by half, thanks to the key contribution of Associate Professor Heng Chun Huat’s group on energy-efficient radios within the FD-fAbrICS joint lab.
Unlike their conventional counterparts, chips based on FD-SOI technology offer superior power efficiency as current leakage is less of an issue. As a result, they consume less power and operate at lower voltages — making them a cornerstone for power-sensitive applications such as wearables and various IoT devices.
“Our research outcomes amplify such power reductions by an order of magnitude through fundamental advances in circuits and architectures.”
“Additionally, our research outcomes amplify such power reductions by an order of magnitude through fundamental advances in circuits and architectures. At the same time, such advances coexist with the traditional flexibility of softwareprogrammable processors, filling the traditional energy-flexibility gap between dedicated accelerators and multi-core systems,” adds Prof Alioto.
Lowering the barriers to entry
Prof Alioto aims to advance the FD-SOI systems and technologies from the laboratory to industry by lowering design barriers. A workshop organised by Prof Alioto and the FD-SOI & IoT Industry Consortium* on 3 May 2024 provided a platform for those from the research community and industry to talk all things FD-SOI — from AI models and wireless communications to digital circuits and system architectures — facilitating knowledge exchange and opening new doors for further collaboration with industry.
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“This innovation has the potential to accelerate the time to market for the key players in Singapore’s semiconductor ecosystem,” adds Prof Alioto. “Through the FD-SOI & IoT Industry Consortium, we intend to drive the adoption and large-scale deployment of our design technologies, giving the nation an edge in the competitive AI and semiconductor arenas.”
At NUS FD-fAbrICS, researchers are now expanding the scope of their work to develop new classes of connected silicon systems that could potentially support larger AI model sizes for AI applications.
* The FD-SOI & IoT Industry Consortium was established in 2023 to extend the impact of the NUS FD-fAbrICS joint lab on Singapore’s semiconductor ecosystem, with Soitec and NXP Semiconductors as founding members.