4D printing: Current research and future applications

4D printing Current research and future applications AR0531 Innovation & Sustainability AR1B025-D3 BT Research Methodology

Nikoletta Christidi 4738594 N.Christidi@student.tudelft.nl 06/11/2017 Number of words: 2477

Focus and restrictions – This paper is focused on the recent advances on programmable matter, especially on the “4D printing” research by MIT. As the issue is tackled from an engineer’s point of view, there is limited analysis on the technical aspect of the material behaviour on a micro-scale.

Abstract – In recent years, there has been an increasing interest on the exploration of a possible “paradigm shift” in additive manufacturing, as research is being carried out on the addition of an extra dimension in 3d printing: that of time. More specifically, researchers in MIT are currently investigating the nature of self-folding assemblies and their possible applications in various fields, such as medical healthcare and building technology. The main research question that was formulated for this paper is the following: What are the recent advances in programmable matter, especially 4D printing, and which are their possible applications in the future building industry?

Key words – programmable matter, 4D printing, smart materials, selfassembly, AR0531

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1 Introduction This paper attempts to discuss the importance of advances in 4D printing in building construction, as well as the paradigm shift these advances are able of causing for the whole society.

The problem spotted that served as the initial motivation for this paper was the fact that 4D printing has been the subject of research for no more than a decade, and thus is not widely covered or well-known among engineers, designers and the public. As researchers in MIT are currently investigating the nature and mechanisms of self-assembling structures, there is the need for a disruptive progress to accommodate this new field of studies.

Based on this problematic, the research objective was therefore formulated. The main objective of this paper was to explore and record the recent advances in programmable matter, especially 4D printing, as well as their possible applications in the future building industry.

Consequently, the definitions of programmable matter, smart materials and 4D printing are provided first, as well as a brief attempt of stating the subtypes of programmable matter is made. Secondly, a synoptic overview of the MIT research on 4D printing is provided.

Finally, the possible applications of this new technology in the building industry are discussed.

2 Methodology The starting point for this paper was programmable matter, as this has been the branding keyword of such technologies for many years. A quick research on the issue of programmable matter led the author to smart materials and the so-called “4D printing”; these were the initial keywords of the literature search. A worth-noting fact is that these keywords, combined with words as “architecture” or “building” didn’t yield adequate results, so it was concluded that the relationship between the new advances in 4D printing and their possible applications in the building industry remains relatively unexplored.

For the literature search, Web of Science and Research Gate were used. For a quick skimming of articles, publications and public opinions on the subject, Google search was used,

while the software Mendeley was used for the recording and organisation of the findings, as well as for taking notes. Finally, the TU Delft repository was also made use of, for exploring the relationship of the author’s University to the said research.

As for the quality assessment of the relevant literature, it relied on the structure of the papers, the arguments used, the number and quality of the references and the publication date. Older publications were studied as well, for the degree and the speed of progress made in the field of 4D printing in the last decade to be assessed.

3 Introduction to programmable matter Programmable matter has been defined as “a material whose properties can be programmed to achieve specific shapes or stiffnesses upon command” (Hawkes, An, Benbernou, Tanaka, Kim, Demaine, Rus & Wood, 2010). The concept of programmable matter was based on computational origami, “an area of computer science” (Hawkes et al., 2010) originating in the 1990s.

The idea that engineers can construct a material that can change its mechanical properties when stimulated has been supported by the recent advances in nanotechnology, “with its interest in “bottom-up” self-organizing systems” (Ball, 2014). The methods used to achieve this robotic-like, yet noticeably biomimetic, behaviour, are multiple and diverse.

As the concept of programmable matter initially focused on small-scale productions, it quickly became associated with additive manufacturing. For the past several years, most of the advances in 3D printing technology have aimed at developing machines “able to print a broad selection of different materials, ranging from plastics to organic materials” (Franssen, T., 2017, p. 11). The challenge for researchers now is to be able to embed the idea of programmable matter in 3D printing, creating parts of products “able to perform a function directly from the manufacturing process” (Franssen, T., 2017, p 11), thus designing not only the 3D printed object, but also the way it will transform through actuation.

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When this transformation takes the form of folding or bending, inspired by traditional Origami folding processes, several “multimaterial self-actuating synthetic systems […] have been reported in the literature for different stimuli methods”, according to Mulakkal, Seddon, Whittell, Manners and Trask (2016).

These methods include “employing polymer swelling and shrinking, shape-memory materials and magnetic materials”; as for the various stimuli used, these include “water, light (photoactive), temperature, pH, electric field, specific solvent and enzymes” (Mulakkal et al., 2016).

4 MIT “4D printing” research 4.1 Introduction to 4D printing Compared to traditional additive manufacturing techniques, the “4D printing” technique, as invented and branded by Massachusetts Institute of Technology (MIT) considers an extra dimension in the process, that of time. According to An, Chua and Mironov (2016), “the main difference from 3D printing is that it involves a programmed shape change over the postprinting time.”

For the realisation of this vision, a group of qualified professionals had to work together.

The research is being conducted by the SelfAssembly Lab at MIT in collaboration with Stratasys Ltd, “an industry leader in the development of 4D Printing” (Tibbits, 2014), and is focusing on “the development of self-assembly programmable materials and adaptive technologies for industrial application in building design and construction” (Tibbits, 2014).

Concerning the concept of embedding a temporal dimension in the manufacturing process, emphasis is being given on the fact that the produced structures are no longer static, but they are “programmably active and can transform independently” (Tibbits, 2014).

Tibbits (2014: 119) stated the following on this new manufacturing technique: This technique offers a streamlined path from idea to reality with performance-driven functionality built directly into the materials.

4.2 How 4D printing works This technology makes use of three basic components: “the machine, the material and the geometric ‘programme’” (Tibbits, 2014). As far as the machine is concerned, Connex machine by Stratasys is used, offering “multi-material PolyJet printing” (Tibbits, 2014).

The Stratasys material research group in collaboration with the Self-Assembly Lab developed a dynamic material, a “hydrophilic polymer” which “expands 150 per cent” upon encountering water (Tibbits, 2014). However, the material printed by the machine is a component combining the “active” material with a “rigid polymer” one, which is used to “give both structure and potential energy” (Tibbits, 2014).

Such complex structures, consisting of both active and passive layers, “can be used as building blocks for more complicated morphing applications” (Yuan, Ding, Wang, Dunn & Qi, 2017), and thus have attracted researchers’ and designers’ attention in the last decades. The exact way of how these structure change shape when stimulated is described by Yuan et al.

(2017: 1): Upon stimulation, the active layer may expand or shrink while the passive layer tends to remain its original shape, which create a mismatch strain and causes the overall bending or curling of the laminated film.

In the research conducted by MIT, the reference to a “geometric programme” concerns the way the rigid and active materials are combined, regarding their position relative to one another, as well as the ratio of their volumes.

These variables later create the conditions that enable their transformation, without the need of an energy source other than their own activation energy.

4.3 Self-assembling structure examples Emphasis is being given by the researchers on the geometrical nature of these transformations, notably on the passage of a 1D or a 2D geometry to a 2D or 3D geometry. The agitator used in all cases was water, taking advantage of the hydrophilic nature of the material perceived as “active”.

The first series of experiments included the production of a single strand of the composite material, which demonstrated either 3

a 1D to 2D shape change or a 1D to 3D shape change when submerged in water. In the first case, the strand was roughly 30 centimetres long, and it transformed into the letters “MIT” (Figure 1). In the second case, three single strands, 46 centimetres, 430 centimetres and 1500 centimetres, transformed into a first, a second and a third-generation fractal Hilbert curve respectively; these curves practically formed 20 centimetres cubes (Figure 2).

When submerged in water, the surface folds into a closedsurface cube with filleted edges.

Figure 3: 4D Printing: Self-Folding Surface Cube.

Source: Self-Assembly Lab http://www.selfassemblylab.net/4DPrinting.php

Figure 1: 4D Printing: Self-Folding Strand into "MIT".

Source: Self-Assembly Lab http://www.selfassemblylab.net/4DPrinting.php

Figure 2: 4D Printing: Self-Folding Strand into 3D Cube.

The picture shows the folding process of a single strand of composite polymer material to a first-generation Hilbert cube over time.

Source: Self-Assembly Lab http://www.selfassemblylab.net/4DPrinting.php

The second series of experiments involved surface transformations. The subject of the printing process was this time a twodimensional flat plane, which represented the cross-like net of a cube. The folding process was described as following (Tibbits, 2014: 120) and is visualised in Figure 3: At each of the joints a long strip of active and rigid materials was printed that describes a 90degree angle limiter that stops the surface from folding when it reaches the final-state condition.

Finally, the MIT research examines a “wide range of other 1D, 2D and 3D transformations” including “self-folding origami, self-healing structures where holes close after encountering water, and other global geometric reconfigurations” (Tibbits, 2014).

5 Current and possible future applications of 4D printing For the new technology to be integrated in the building design process and be used by designers from across the globe, the MIT SelfAssembly Lab has established a cooperation with AutoDesk Research for the development of a relative software package, offering “simulation for self-assembly and programmable materials as well as optimisation for design constraints and joint folding” (Tibbits, 2014). This way, they aim to eliminate the traditional sequential relation between simulation and building; in contrast, Tibbits (2014: 121) states that: This workflow aims to create simulations that adjust physical performance and materials that promote new simulated possibilities, offering top-down and bottom-up evolution of design possibilities both physically and digitally.

Since the introduction of programmable matter, the vision for the future of product design has changed drastically, as new technologies and materials are becoming available. Concerning small-scale design, engineers and designers are envisioning products that will be able to adapt themselves to 4

external stimuli, whether these come from the user or the environment. Such stimuli could include “biometric information, body temperature, sweat and internal pressures” or “moisture content, temperature, pressure, altitude or sound” (Tibbits, 2014).

Passing from small-scale to big-scale production, such as architecture and building construction, we can imagine that the professionals of these fields are gradually bringing programmable matter in the centre of attention. Zarzycki and Decker (2017:1) describe:

Architect + Oliver David Krieg + Steffen Reichert, 2013, para. 3).

Adaptive designs and intelligent spaces […] engage users in interactive dialogue, allow for public domain authoring, and are critical factors in sustainable designs where buildings monitor their own performance and respond to environmental factors or user needs.

More specifically, the possibility of integrating 4D printed programmable matter on roofs and façades is already considered. As typical adaptive façade systems and opening roofs require complicated controlling systems to function, they remain “energy intensive, highly reliant on failure prone, and expensive mechanisms” (Correa et al., 2015). Instead, 4D printed façades could be actuated according to changes in weather conditions, without a further need for input energy.

While this technology has not yet been implemented in mass architectural applications, there have been attempts of testing it in largescale constructions such as pavilions and installations. Perhaps the most famous among them is the “HygroSkin - Meteorosensitive Pavilion” by architects Achim Menges, Oliver David Krieg and Steffen Reichert in collaboration with the Institute for Computational Design and Construction (ICD) of the University of Stuttgart.

The design of the aperture elements (Figure 4), inspired by spruce cones, enables for an adjustment of the degree of openness and porosity of the external surface of the pavilion, as the thin wooden elements respond to “relative humidity changes within a range from 30% to 90%, which equals the humidity range from bright sunny to rainy weather in a moderate climate” (HygroSkinMeteorosensitive Pavilion / Achim Menges

Figure 4: Process-Responsive component.

The picture visualises the movement of the bilayered wooden scales in response to changes in relative humidity.

Source: ArchDaily https://www.archdaily.com/424911/hygroskinmeteorosensitive-pavilion-achim-menges-architect-incollaboration-with-oliver-david-krieg-and-steffen-reichert

Finally, although one could argue that the high cost of 4D printed materials would render them unusable for large-scale production, the concept of adaptability positively affects the long-term efficiency of products and buildings. For example, commerce and transportation could benefit from 4D printing technology, as products could be packaged flat and “activated on delivery to full volume and functionality” (Tibbits, 2014).

Furthermore, the possibility of including in buildings parts that automatically “errorcorrect”, “self-repair” (Tibbits, 2014) and even self-disassemble when no longer efficient, means that the use of programmable matter in architecture will also change the whole concept of maintenance and restoration.

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In conclusion, by using programmable matter principles, engineers and designers will be able to “actively adjust material properties with the use of voltage, light, and magnetic or electric fields” through digital computing. Thus, the much-needed paradigm shift will be achieved: the era of “smart” buildings will be followed by the era of “truly adaptive and potentially autonomous buildings” (Zarzycki & Decker, 2017).

programming, and thus predicting future conditions and needs of the environment, the users and the product itself, as well as to material science, which already deals with issues of efficiency and cost. Self-adjusting materials could, potentially, change not only the world as we know it, but also our active participation in the formation of the new world, given that they escape the laboratory environment and start being applied to real life situations.

6 Conclusions

References

This paper was formulated as an answer to the following research question:

An, J., Chua, C. K. & Mironov, V. (2016). A perspective on 4D bioprinting. International Journal of Bioprinting, 2 (1), 3. doi: 10.18063/IJB.2016.01.003

What are the recent advances in programmable matter, especially 4D printing, and which are their possible applications in the future building industry?

Ball, P. (2014). Make Your Own World With Programmable Matter. Retrieved from https://spectrum.ieee.org/robotics/roboticshardware/make-your-own-world-with-programmablematter

Therefore, programmable matter as a concept was defined and examples of relevant research were briefly introduced. Emphasis was given in the “4D printing” research by the MIT SelfAssembly Lab in collaboration with Stratasys Ltd. The role of active and passive layers of materials combined in a single structure were examined, and examples of such structures transforming in various ways when submerged into water were presented. Finally, possible applications of programmable matter in smallscale and large-scale production, as well as the way these would change the building industry, were described. It is worth noting that, as the research is still at an early development stage, actual case studies of the way this technology can be applied in architecture do not yet exist.

Correa, D., Papadopoulou, A., Guberan, C., Jhaveri, N., Reichert, S., Menges, A. & Tibbits, S. (2015). 3D-Printed Wood: Programming Hygroscopic Material Transformations. 3D Printing and Additive Manufacturing, 2 (3), 106. doi: 10.1089/3dp.2015.0022

7 Reflection The brand name “4D printing”, was the source that fuelled the curiosity feelings that led to this paper. Initially, the only elements known to the author on this subject were the keywords “programmable matter” and “4d printing”, which provided the basis for the literature search that followed. It would be safe to assume that the topic of programmable matter will be a part of future discussions on innovation and sustainability, as it is directly related to

Franssen, T. (2017). Shape-memory alloy in 3d printing (Master's thesis).

Retrieved from https://repository.tudelft.nl/islandora/object/uuid:800ab e5b-9c17-4d41-bdda-bfd9c32545b7?collection=education Hawkes, E., An, B., Benbernou, N. M., Tanaka, H., Kim, S., Demaine, E. D., Rus, D. & Wood, R. J. (2010). Programmable matter by folding. Proceedings of the National Academy of Sciences, 107 (28), 1. doi: 10.1073/pnas.0914069107 HygroSkin-Meteorosensitive Pavilion / Achim Menges Architect + Oliver David Krieg + Steffen Reichert. (2013).

In ArchDaily. Retrieved from https://www.archdaily.com/424911/hygroskinmeteorosensitive-pavilion-achim-menges-architect-incollaboration-with-oliver-david-krieg-and-steffen-reichert Mulakkal, M. C., Seddon, A. M., Whittell, G., Manners, I. & Trask, R. S. (2016). 4D fibrous materials: characterising the deployment of paper architectures. Smart Materials and Structures, 25 (9), 1-2. doi: 10.1088/09641726/25/9/095052 Tibbits, S. (2014). 4D printing: Multi-material shape change. Architectural Design, 84 (1), 118-121. doi: 10.1002/ad.1710 Zarzycki, A. & Decker, M. (2017). Programmable buildings.

ACM SIGGRAPH 2017 Talks on - SIGGRAPH '17, 49, 1-2. doi: 10.1145/3084363.3085164

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