Material TransformationDesigning Shape Changing Interfaces Enabled by

Programmable Material Anisotropy

Jifei Ou

Dipl. Design, Offenbach University of Art and Design (2012)

Submitted to the Program in Media Arts and Sciences, School of Architecture and Planning, in partial fulfillment of the requirements for the degree of Master of Science in Media Arts and Sciences at the Massachussetts Institute of Technology

June 2014© 2014 Massachusetts Institute of Technology. All Rights Reserved

Author Jifei Ou

Program in Media Arts and SciencesMay 24, 2014

Certified by Hiroshi Ishii

Jerome B. Wiesner Professor of Media Arts and SciencesMIT Media Lab

Accepted byPattie Maes

Associate Academic Head, Program in Media Art and Science

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Material TransformationDesigning Shape Changing Interfaces Enabled by

Programmable Material Anisotropy

Jifei Ou

Submitted to the Program in Media Arts and Sciences, School of Architecture and Planning, on May 30th, 2014in partial fulfillment of the requirements for the degree of Master of Science in Media Arts and Sciences at the Massachussetts Institute of Technology

ABSTRACT

This thesis takes a material perspective on designing trans-formable interfaces. The structure of material and mechan-ical properties such as stiffness, can determine not only its static performances, but also, with the help of exter-nal forces, support dynamic shape change. By encoding structural or stiffness distribution in the actuated mate-rials, we can partially offload the shape-changing control from actuators (digital) to the material itself (analogue), in order to achieve expressive transformations that cur-rent modularized actuation system cannot easily provide.

The implementation of this thesis will be three series of material primitives and three application prototypes that demonstrate the real world potential of this research.

Thesis SupervisorHiroshi IshiiJerome B. Wiesner Professor of Media Arts and SciencesMIT Media Lab

Material TransformationDesigning Shape Changing Interfaces Enabled by

Programmable Material Anisotropy

Jifei Ou

The following people served as readers for this thesis:

Thesis AdvisorHiroshi Ishii

Jerome B. Wiesner Professor of Media Arts and Sciences MIT Media Lab

Thesis ReaderNeri Oxman

Assistant Professor of Media Arts and Sciences MIT Media Lab

Thesis Reader Sangbae Kim

Assistant Professor of Mechanical Engineering MIT Department of Mechanical Engineering

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CONTENTS

ABSTRACT 03

ACKNOWLEDGEMENTS 11

INITIAL REMARKS

Chapter 1. INTRODUCTION 1.1 Motivation 17 1.2 Thesis Aims 19 1.3 Thesis Contribution 21 1.4 Thesis Outline 21

Chapter 2. MACHINE TO MATERIAL TRANSFORMATION 2.1 Mythology of Shapeshifting 24 2.2 Transformable Machine 24 2.3 Programmable Matter & Claytronics 28 2.3 Shape Changing Interfaces 29 2.5 Smart Materials 32

Chapter 3. MATERIAL, FORCES AND INFORMATION 3.1 Transformation in Nature 35 3.2 Material Computation 38 3.3 Model for Material Transformation 40

Chapter 4. PNEUMATIC ACTUATION PLATFORM 4.1 Inspiring Works 4.1.1 Soft Robotics 44 4.1.2 Tunable Stiffness with Jamming 45 4.2 Principle of Layer-jamming 46 4.3 Control Systems 4.3.1 Inflation for Deformation 47 4.3.2 Vacuum for Tunable Stiffness 48

Chapter 5. PROPOSED DESIGN SPACE 5.1 Parameter 5.1.1 Deforming Forces 52 5.1.2 Programmable Material Anisotropy 54 5.2 Design Space 56 5.3 Transformation Primitives 5.3.1 Type A Primitive A 57 Primitive B 58 Fabrication 60 5.3.2 Type B Primitive C 61 Primitive D 63 Fabrication 66 5.3.1 Type C Primitive E 67

Chapter 6. APPLICATIONS AS EVALUATION 6.1 Design Principles 70 6.2 HelighX Design 70 Sensing 71 Fabrication 72 6.3 PLYABLES Design 72 Extention of Application 75 Sensing 73 Fabrication 75 6.4 JamBot Design 76 Sensing and Motion Control 76 Fabrication 77

Chapter 7. A STEP FORWARD... 7.1 Morphing Vehicle 79 7.2 Beyond Transformation 7.2.1 Illumination 81

7.2.2 Sensing 82 7.2.3 Construction 82 7.2.4 Nano-Actuator Distribution 83

Chapter 8. CONCLUSION 85

APPENDIX 87

BIBLIOGRAPHY 91

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ACKNOWLEDGEMENTS

I would like to thank Lining Yao, my dearest friend, and smartest collaborator. Without you, none of the projects would become tangible. Thank you for all the help, trust, fight, and laugh. Thank you for walking me through the transition from being a designer to a researcher.

My deepest gratitude goes to my role model, my advisor Prof. Hiroshi Ishii. Thank your for your appreciation when I was still in Germany. Thank you for constant modifying and debugging my brain. Thank you for making me believing in vision that transcends life and spirit.

Thank you Prof. Neri Oxman and Prof. Sangbae Kim, for your unique thoughts, comments, and suggestions. Thank you for trusting me and being extremely supportive. I am fortunate that such brilliant and inspiring people sur-rounded me. Without your help this thesis would not have been possible.

My collaborators: Daniel Tauber, Ryuma Niiyama, Juergen Steimle. I could never thank you enough. The works would never become solid without you.

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Thank you Daniel Leithinger and Sean Follmer for your pioneer work on Jamming UI. I truly appreciate all the dis-cussions, suggestions and tolerance in the past two years. Thank you Xiao Xiao, for sharing philosophical thoughts, for creating MirrorFugue, which inspires and moves me all the time.

Thanks to All the TMGler: Tony Tang, Felix Heibeck, and Philipp Schoessler for the discussion, support and help. Basheer Tome, you are an amazing designer. I hope we could collaborate more in the future. Thank you Leonar-do Bonanni and Amanda Parkes for the appreciation and encouragement.

Prof. Pattie Maes, Prof. Ethan Zuckerman, Prof. Tod Macho-ver and Elliot Hedman, thank you for your valuable sugges-tions and critics during the crit-day of my thesis.

Thanks to Linda Peterson and Keira Horowitz for making sure that all papers wen to the right place with the right signature at the right time. You make every students enjoy-ing the life in the lab more.

I want to give the special thank to my former advisor Prof. Frank Zebner, my friend Prof. Jussi Ängeslevä and my for-mer employer Joachim Sauter. Thank you for teaching me how to think and act as a designer. Thank you Prof. Achim Menges and Steffen Reichert from my former university, for your extraordinary vision and works that have been inspir-ing me ever since I know you. I learned more than I could imagine from you.

Thank you Pragun Goyal, Carlos Gonzalez Uribe, Valentin Heun, for debating, joking, and meditating with me. We spent two wonderful years together in the lab.

Thank you Dhairya Dand, Gershon Dublon, Nan Zhao, Jie

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Qi, Anirudh Sharma, Robert Hemsley, Jared Laucks, Travis Rich, Daniel Novy and Sujoy Kumar Chowdhury, for the laughs, late nights, critical discussions and just about ev-erything that made the last two years in the lab possible.

Thank you Steven Keating, Samuel Calisch, William Lang-ford, Markus Kayser for being so awesome. I am so proud to be your friend. Thank you for all the help. Thank you Nathan Linder, Philippa Mothersill, Jennifer Jacobs, Matt Hirsch, David Mellis, for the brainstorming and helping.

Thanks to all the UROPs who helped the design, fabrica-tion and documentation process: Grace Lee, Erica Green, Clark Della Silva, and Kaleb Ayalew. You guys showed me how smart an MIT undergrads should be.

Foremost, I am thankful to my aunt, my father and my brother. Thank you for being supportive, understanding and loving all the time.

Thank you grandma.

- Jifei

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Initial Remarks

Physical materials usually are considered having the opposite characteristics of digital information. They are static, passive, and permanent, etc. What you are about to read, is my effort to augment physical materials with characteristics of digital information: dynamic, active, and programmable. The characteristics are embodied by the capability of physical transformation. The new materi-als with such abilities could be used to construct a more responsive living environment; accelerate the process of design and making; and enhance our existed interaction with products or information, etc.

Under this vision, this thesis presents a combination of two intertwining research thread. The first one is a meth-odology framework of designing physical transformation by learning from the optimized way of how Mother Nature form and transforms living materials. The second looks at different application scenarios in which transformable ma-terials can be applied to support future human-computer interaction (or human-material interaction).

Hopefully this thesis will inspire ideas, suggest new direc-tions and guide the development towards a future where atom and bits are truly integrated.

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INTRODUCTION

As a negotiation between computation and physical material, Tangible User Interface (TUI) leverages the meta-phor of physical object and human bodily experience with physical inert materials to build an intuitive experience with digital information (Ishii, 2008). This is the core con-cept of “Tangible Bits”. Today, we are standing at a point where “Tangible Bits” is transforming into “Radical Atom” (Ishii, et al.). It is a vision that questions our fundamental experience with physical material: What if inert materials become dynamic as pixels on the screen? How can such materials make sense to us?

To embody such concept, TUI expands it focus from pas-sive to actively transformable materials. Such materials should not only be able to change physical shape, but also other properties (color, stiffness, refractive index, etc.) The transformation should be able to be controlled, pro-grammed, and even synchronized with digital information. At its core, Radical Atoms seeks integration, instead of negotiation between bits and atoms. As we pursuing the vision of Radical Atoms, we are en-countering a new range of design problems: how do we

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prototype such physical processes of transformation? Pioneer works have been focusing on designing trans-formable machines using hard mechanics. They gave us an exciting preview of future human-material interaction. Yet this approach of designing “machine” is limited by the size, weight and energy consuming of actuators. How can we scale the transformation up or down for different us-age? Without scalability, Radical Atoms cannot truly reveal its potential in real-world application. How can we design materials that transforms? While designers have numer-ous techniques and tools to improve the appearance of objects, similar method for creating ways to model materi-al transformation are lacking.

If we want to depict a convincing picture of future Radical Atoms, we need to find an ecological way of designing transformable materials that can creates numerous real world applications. Proposed here is an alternative meth-od of constructing future shape-change interfaces. This approach looks at how can we shift our attention from programming the actuator (force) to the structure (materi-al). Rather than repetitively patching actuators (be it gear motors or smart materials) on the material, then connect-ing them to a global controller, we should directly encode transformation information into the inert materials. By giving them different energy sources (forces), they should accomplish a reversible shape-change as encoded.

In the natural world, the phenomena of property-change are always conducted on the material level. Nature utilizes both forces (internal or external) and material anisotropy to create amazing material transformation through space and time. Anisotropy means direction dependent. It is the heterogeneous distribution of material. The octopus’ camouflage phenomenon is a result of adjusting the size of chromatophore cells on the skin; wooden veneer curves directionally based on the directional structure of its fiber when absorbing environmental humidity (Menges & Re-

Figure 1. (a) The camouflage behavior of octopus. (b)A octopus changes the size of chromatophore cells to adjust the skin color .

a

b

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ichert, 2012). Materials’ structural anisotropy play a signif-icant role in those transformation processes. In this the-sis, I propose that, if we are going to build materials that have dramatic and scalable transformation, we should learn from nature’s optimized way of building formation and transformation by leveraging material anisotropy. It is not about bio-mimicry design. Nature’s examples only provide us a perspective. The material’s anisotropy can be also encoded or programmed to archive complex transfor-mation.

However, programming materials anisotropy does not suggest giving up on controlling the force. In this thesis, I also draw a spectrum of deforming forces: computational, manual, and environmental. The controllability/program-mability decreases in such order. This is another param-eter of designing Material Transformation. Together with programmable material anisotropy, I propose a design space in which six types of transformation are described. I then present a serial of physical shape-change primitives based on the type of transformation, which evolve to three prototypes as real-world applications.

Aims

This thesis postulates that the ability to design, program and prototype the shape changing interfaces is becoming increasingly important as the programmability is shifting from digital to physical world. The thesis aims to create design framework for programmable material transforma-tion by examining the relation between material anisot-ropy and deforming forces. I aim to establish two main parameters of the framework:

1. Deforming ForcesComputational: External computationally controllable ac-tuator connected to the interfaces causes their transforma-

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tion. Air pressure is selected the prototypes in this thesis. Manual: Human body’s direct action upon the physical interfaces causes their transformation. Such as bending, pressing, pushing, etc.

Environmental: Natural forces acting upon physical inter-faces cause their deformation. Such as gravity, wind, etc. 2. Programmable Material AnisotropyEncoded Stiffness Distribution: location, density and direc-tion of material stiffness distribution can be designed and fabricated.

Dynamic Tunable Stiffness: a dynamic material stiffness changing can be achieved by using jamming technique.

By pairing those parameters, I aim to show a wide design space for material transformation.

Figure 2. The Design Space of Material Tranformation for this thesis.

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Contribution

This thesis offers the following contributions:

1. An integrated framework of designing shape-change in-terfaces. Material anisotropy should be added to the agen-da of designing shape-change interfaces in Human-Com-puter Interaction (HCI). It could help us build expressive transformable objects more easily.

2. A pneumatic actuation platform that allows material change shape and stiffness.

3. Application prototypes show how transformable materi-al can be used in everyday life.

4. Provide a material perspective for interface designer to play with smart materials beyond shape-change. The old “patching” approach leaves designer little space for cre-ation. By introducing programmable anisotropy, designers could maximize the creativity with limited technology.

Thesis Outline

the following chapters describe the evolution of ideas in this thesis:

Chapter 2: introduces a context and previous work on de-signing physical transformation. I distinguished Machine and Material Transformation and pointed out the interests shift from machine to material.

Chapter 3: gives a series of examples of how nature trans-form organism by encoding information in the material structure. Nature weaves energy, material and information together to create complex transformation. Yet man-made shape-change interfaces tend to isolate them.

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Chapter 4: describes a pneumatic platform for designing material transformation. a pneumatic system can be used to deform a soft body and change their stiffness.

Chapter 5: presents a design space with primitives of transformable material. Sis types of Material Transfor-mation are explained. The chapter also presents three of those types with physical shape-change primitives.

Chapter 6: offers three application prototypes as an eval-uation of the framework. They are HelighX, PLYABLES and JamBot.

Chapter 7: discusses how the programmbale anisotropy can be extended beyond shape transformation. How can designers utilize it for other perspective of interface de-sign, such as property-change, self-assembly, etc.

Chapter 8: concludes the thesis with a summary.

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Machine to Material Transformation

To consider transformable materials in design practice first we need to establish a context of human controllable physical transformation. Mark Weiser once envisioned: “The most profound technologies are those that disap-pear. They weave themselves into the fabric of everyday life until they are indistinguishable from it.” (Weiser, 1999) As human beings have been designing, building and improving machines that can transform by using hard mechanics (linkages, gears, etc.) since long, now we are standing at a point, where materials that change shape are desired. For instance, instead of constructing sophis-ticated mechanical structure for foldable furniture, now imagine a piece of clay that actively changes its shape from one to another.

As it is radpidly developing, man-made technology is shifting from focusing on machine transformation to mate-rial transformation. Here, machine refers to human-scale mechanical structures that support transformation. Ma-terial refers to wood, fabric, polymer, etc that can deform under certain stimuli. Certainly material transformation is a result of material structure (atomic, molecular ) change. In this chapter, I will go through several examples of phys-

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ical transformation design to demonstrate the interests shfift from transformable machine to material. This shift has also influenced the development of Shape Changing Interfaces in HCI.

Mythology of ShapeshiftingFrom ancient Greek to ancient China, if we look back at hu-man mythology and literature, it is not difficult to find the origin of human’s desire and fascination with transform-able material. Although they are pure imagination of the physical world, they depict scenarios of how human would interact with those transformable matter.

One of the most famous transformable objects is Ruyi Jin-gu Bang (Chinese: 如意金箍棒). It is magical staff wielded by the Monkey King Sun Wukong in the 16th-century clas-sic Chinese novel <Journey to the West>. Anthony Yu trans-lates the name simply as “The Compliant Golden-Hooped Rod,” It is described as being made out of black iron, with gold bands on the ends. It has the ability to shrink to the size of a needle, as Monkey King stores it in his ear when not using it, and grow back to the size of staff as weapon. (Figure 3)

Transformable MachineIn reality, human beings have been building kinetic ma-chines in the context of transformable objects or architec-ture. The machines are usually constructed with homog-enous materials. Through a set of mechanical principles they can be assembled together to exhibit certain transfor-mation ability.

The Expanding Geodesic Dome by Hoberman Associate, opens from a 1.5-meter cluster to a 6-meter structural dome when pulled open from its base. When deployed it has the same shape and triangulated pattern as Buckmin-ster Fuller’s static, geodesic dome. This movable lattice is

Figure 3. An illustration of Ruyi Jingu Bang and Monkey King

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formed from the edges of the icosidodecahedron, a cross between the dodecahedron and the icosahedron. Under the similar design principle, one can develop a ring, a sphere, even a curved surface that can expand or shrink.

Similarly, many designer have been developing transform-able furniture to meet different need in domestic scenari-os. The table and bench combination by Uwe Fischer and Achim Heine, can be extended and retracted by means of numerous folding grilles and is therefore variable in length. The rollable tabletop is constructed like a rolling blind and adapts to these movement. It can be stored in a crate-like container together with the grilles. This work inspired other future development oon transformable furniture design.

Figure 4. The Expanding Geodesic Dome by Hoberman Associate. 1991

Figure 5. The table and bench combination by Uwe Fischer & Achim Heine, 1987

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Beyond scaling the volume of physical objects, some artists interpret transformation as assembly and disas-sembly. Arthur Ganson’s famous kinetic sculpture “Cory’s Yellow Chair” decomposes a wooden chair model into several pieces, which are connected to the ends of a large mechanical system. The gears in the system rotate to move the wooden pieces away from each other. After a cy-cle they can be brought back together to form the original shape of the chair.

Max Dean, in collaboration with roboticist Raffaello D’an-drea, created a robotic chair that can self assemble and disassemble. It is not only a piece of technological work, but also a design prototype that envisions how future fur-niture could be, and proposes a question of how we could interact with such object. The Robotic Chair looks like a generic wooden chair. Unlike most chairs, however, this one falls apart and puts itself back together. The Robotic Chair is guided by an overhead vision system and con-trolled over a wireless network by an external computer. Various algorithms govern the chair’s behavior, while the software is structured in such a way that the system can learn from its environment. The Chair keeps its controls

Figure 6. Cory’s Yellow Chair by Arthur Ganson. 1997

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and technology hidden under a simple wooden veneer, making it high-tech in the most unassuming way.

More recently, designers also look at mechanical systems with high controllability that facilitate abstract physical transformation. The kinetic sculpture by Art+Com is a com-mercial work for BMW. The sculpture uses 714 metal balls that are individually suspended one barely visible string, creating an seemingly weightless, amorphous mass. Each ball lowers and retracts independently, which allows them to approximate different forms, from simulating water wave to construct the fluid surface of a car.

Figure 8. The Kinetic Sculpture by Art+Com. 2008

Figure 7. The robotic Chair by Max Dean & Raffaello D’andrea assembles and disas-sembles by itself. 2006

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Programmable Matter & ClaytronicsArt works express our desires to a physical world that can be rapidly transform. In the field of robotics, much effort has been made to realize such desire. Programmable Matter (supported by DARPA and the Wyss Institute, Har-vard) is a new concept for reconfigurable systems based on self-folding or self-assembly. One example is the Self-folding Sheet by MIT Distributed Robotics Lab (Figure 9). These sheets are constructed from smart materials that embed actuation, computation, communication, and sensing. Embedded actuators are used to self-assemble flat sheets into 3D robots with specified functionality.

Another example, the self-reproducing machines demon-strated here are essentially modular robots. Their modules have electromagnets that selectively weaken and strength-en connections, determining where the structure breaks and joins. Each module is a 10cm cube, split into two halves along the plane. One half of the cube can swivel relative to the other half in increments of 120 degree, each time cycling three faces of the cube. Connected cubes can both form and change into arbitrary arrangements

However, the challenges lie between Programmable Matter

Figure 9. The Self-folding Sheet by Daniela Rus’ Distributed Robotics Lab, MIT. 2007. (a) A 4 by 4 units of self-folding sheet. (b) Folded into a table. (c) Folded into a pinwheel.

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and the reality are not only the high energy consuming for the transformation, but also the physical limitation of the size, weight and dimension of the electronic components as they need to be all “patched“ on the passive materials. Thus so far the Programmable Matter remains difficult to scale up.

Claytronics, as an emerging vision, seeks to achieve high-er freedom and precision of physical transformation by embedding miniature sensors, actuators and controllers into a single unit. Just as computer screen is composed by numerous pixels that change colors, Claytronics envisions a world that is composed with numerous such physical units. Each unit can sense where the others are, and change its position correspondingly to form the desired macro shape.

Shape-changing InterfacesDeeply influenced by the kinetic art and robotic field, recent research in Human-Computer Interaction (HCI) looks beyond static, rigid physical interfaces, and ex-plores the rich transformability of input/output devices [12]. Shape-changing Interfaces is a vision that future physical objects can be deformed and adapted to any non-planar surface [29]. Enabled by different technology,

Figure 10. Self-reproduction of a physical, three-dimensional 4-module robot. 2005 (a) A basic module and an illustration of its internal actu-ation mechanism; (b) Three snapshots from the first 10 seconds showing how a 4-module robot transforms as its modules swivel simultane-ously.

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Shape-changing interfaces investigate the dynamic inter-action that derives from actively changing forms of inter-faces.

Recompose (Figure 11) and inForm (Figure 12) look at how

Figure 11. Recompose allows user to control the transformation of a surface by hand gestures. 2010

Figure 12. inForm by Daniel Leithinger & Sean Follmer consists of 900 individually controllable pins that can lift up and down, MIT Media Lab, 2013

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we could interact with 2.5D Shape display. Similar to the kinetic sculpture by Art+Com, Recompose and inForm have a matrix of plastic pins that can lift up and down. User can use gesture or direct manipulation to change the shape of the surface. As the physical 2.5D model is synchronized with its digital model, the surface actively deforms itself, too. However, like other robotic system, such interface requires a large set of motor control, which limit its scal-ability.

Shutters takes another approach of constructing shape-change by compositing Shape Memory Alloy (SMA) into soft fabric. As one examples of his Thesis, Marcelo showed the potential of using SMA as a substitute of gear motors to deform soft flexible material. As SMA has a smaller dimension than usual gear motor, it can be easily attached on the surface that one wants to deform, and gives people a perception of material transformation, instead of ma-chine transformation.

Similarly, morePhone is a prototype of future cellphone that bend its shape to give users a silent yet visual cue of an incoming phone call, text message or emailA set of SMA is attached on a flexible display to archive the bending. It shares the similar construction principle as

Figure 13. Shutter by Marcelo Coelho. MIT Media Lab, 2008

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Shutters.

Smart Materials The emerging interests on SMA bring our attention to the deployment of Smart Materials in HCI. A smart material refers to a highly engineered material that responds intelli-gently to their environment (Addington & Schodek, 2005). The response can be mechanically or optically, etc. The figure below lists out some of the current popular smart materials by comparing the relationship between input stimulus and output response.

In this thesis, we focus on the mechanical output, which allows material transformation. Recently, more and more researches in HCI utilize smart materials to leverage input, output, power storage and communication for interface design. As the project Shutters demonstrated, smart

Figure 15. Stimulus-response matrix for selected materials, Modified from Textiles Future

Figure 14. morePhone, Queen’s University Human Media Lab, 2013

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materials shift our attention from machine to material transformation, from hard to soft mechanics. Smart mate-rials, like SMA, Ferro fluid, Electro-Active Polymer, enables interface/product designers to think about physical trans-formation from material perspective.

However, most current attempts to implement smart ma-terials in interface/product design simply propose smart materials as replacement or substitutes for more conven-tional materials or actuators. Smart materials are typically patched atop an existing structural system. It still follows a paradigm, in which actuators and actuated materials are separated, isolated. Take Shutters for example. If we change the fabric to another soft material (e.g. rubber), its topological transformation will stay the same (although the degree of bending might vary based on the substrate’s Young’s Modulus.)

Such patching strategy remains still repetitive assemblies and difficult to scale up as it is typically maintained by global control, just as modularized gear motor system. If we want to construct complex three-dimensional transfor-mation, this “patching” approach would result numerous cable attached on the material surface and high energy consuming. It is difficult to demonstrate a real world appli-cation with that.

So the question I would like to propose is: Can we propose an alternative design approach to achieve more expres-sive material transformation that current modularized ac-tuation system cannot easily do? Can we partially offload the shape-change control from actuators (digital) to the material itself (analogue)?

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Material, Forces and Information

“Above all we must remember that nothing that exists or comes into being, lasts or passes, can be thought of as en-tirely isolated, entirely unadulterated. One thing is always permeated, accompanied, covered or enveloped by anoth-er. It produces effects and endures them.” — Johann Wolfgang von Goethe

Transformation in Nature

It has been commonly agreed that Nature creates solu-tion with maximal performance using minimal resources. Nature’s inventions have been also inspiring human ac-tivities and inventions. Now let’s slow down the speed of chasing new enabling technologies of actuator, and look at how nature transforms things. In the natural world, the phenomena of shape-change are always conducted on the material level. The octopus’ camouflage phenomenon is a result of adjusting the size of chromatophore cells on the skin; wooden veneer curves directionally based on the di-rectional structure of its fiber when absorbing environmen-tal humidity [1]. Materials’ geometry and structure play a significant role in that transformation processes. However,

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they have been neglected in man-made shape-changing interfaces.

Take a close look at dry leaves. When leaves are alive, they are all flat. After they dry out, the surface curves up in different angle and degree to form varies shape. Where the leaf veins are thick, it stays flat; where veins are thin, the surface bends. The end form is an equilibrium state after constant negotiation between gravity and the distribution of veins. The leaf vein serves as a material constraint that contributes to the end shape.

Another example of the transformation of natural mate-rial is the wooden veneer and its hygroscopic behavior (Niklas, 1992). When a piece of wooden veneer is taken

Figure 16. Diagram of a transverse section through a tree trunk illustrating the deformations that result when blocks of secondary xylem (wood) are taken out and allowed to try. the in situ geometry of each block of wood is shown by solid lines; the bent outline of each block, once it is removed from its original location, is shown by dotted lines

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out of the tree trunk and let to be dried, the veneer will curves up to different direction due to its very fibrous structure. Figure 16 shows the relation between defor-mation and fiber orientation. The property of directional dependency is termed as Anisotropy. It implies the ununi-formed distribution of physical material that causes het-erogeneous mechanical properties. As core of this thesis, I will discuss later how to design material anisotropy to control its transformation.

Not only transformation, Nature constructs functional-ity through material structure and geometry. While pig-ment-based colors feature in the most abundant tech-niques used to create color stimuli in nature, the brightest

Figure 17. Diagram of a transverse section through a tree trunk illustrating the Chrysochroa fulgidissima (the Japanese Jewel Beetle). (a) The elytra and the ventral side of this beetle display bright and iridescent colors that show a strong angular dependence. (b) A multilayer stack with appropriate thicknesses and re-fractive index of the constituent films causes interference of light and strong spec-tral selectivity for the reflected color, scale bar 400 nm. Irregular deformations of the multilayer - (c) optical micrograph, scale bar about 100 um, and (d) scanning electron micrograph, scale bar 10 lm - assure scattering and the visibility of the color over a wide angular range. All pictures are taken from <Photonic Structures Inspired by Nature>.

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and most intense colors result from the interaction of light with complex structures on the micro- and nanoscale. The shell of Japanese jewel beetle shows a remarkable metal-lic iridescence on its elytra1 and on its ventral side (Figure 17a). a multilayer arrangement in the epicuticle layer of the beetle shell is the responsible structure for the bright iridescent colors.This layer structure is made up of 20 alternating layers with refractive index n1 = 1.5 and n2 = 1.7. Irregular structures on the surface of the beetle shell (Figure 17d) assure that the beetle’s strong color appears not only in the direction of specular reflection but can also be observed from other angles (Kolle, 2011).

Through the cases presented above, we can see that Nature creates function and transformation by combining pre-defined structure and passive force, instead of pre-de-fined force and passive structure. The heterogeneous distribution of material (a pre-defined structure) gives us the opportunity to shift the controllability from the envi-ronmental forces to the material construction.

Material Computation

Architects have been learning from Nature to build respon-sive artifacts that leverage the heterogeneous material structure. The emerging field of Material Computation in Architecture explores how material properties; micro-scale structures and behavior can now be seen as information that can be processed (compute) (Ahlquist & Menges, 2011). As active design generators, they can be calculated, arranged, and fabricated to archive certain functionalities.

Carpal Skin is a prototype for a protective glove to protect against Carpal Tunnel Syndrome, a medical condition in which the median nerve is compressed at the wrist, leading to numbness, muscle atrophy, and weakness in the hand. Carpal Skin is a process by which to map

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the pain-profile of a particular patient—its intensity and duration—and to distribute hard and soft materials to fit the patient’s anatomical and physiological requirements, limiting movement in a customized fashion. It is an exam-ple of designing material distribution to archive desired material performance.

Figure 18. Carpal Skin by Neri Oxman maps the pain distribution on human hands to the local thickness change of material.

Figure 19. HygroScope is a prototype that changes permeability as environmental humidity varies.

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HygroScope explores a novel mode of responsive archi-tecture based on the combination of material inherent behavior. Inspired by the pinecone that opens and closes to release seed based on the humidity change, this work utilizes the directional instability of wood, as described previously, in relation to moisture content is employed to construct a climate responsive architectural morphology. Suspended within a humidity controlled glass case the model opens and closes in response to climate changes with no need for any technical equipment or energy.

Model for Material Transformation

The journey to the Nature gives us an opportunity to reflect how can we design and construct next generation shape-change interfaces with expressive transformation in an ecological way. Nature not only operates difference forc-es to deform materials (Just as we use motors or SMA to actuate interfaces), but also creates material structure to assist formation and transformation.

We can then define three factors that are essential for a transformable system (machine or material).

Material: The physical matter, soft or hard, that performs the transformation.

Forces: The operation of energy, internal or exter- nal, that actuates the material.

Information: The instruction of how the transforma- tion should be.

The abovementioned approach of design Machine Trans-formation can be conclude as a model below:

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If machine transformation looks at how encoded energy distribution can actuate materials directly, material trans-formation focuses on how the transform information can be offloaded to the material structure. As Nature encodes the shape-change information in the material instead of forces, Similarly, We can either encode the Information in the Force or Material to design next generation of trans-formable interfaces.

Figure 20.

Figure 21.

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Pneumatic Actuation Platform

“The finest workers in stone are not copper or steel tools, but the gentle touches of air and water working at their leisure with a liberal allowance of time.” — Henry David Thoreau

The previous chapter provides a conceptual model of constructing transformable material. To embody such model, a serial of transformable primitives and designs were made. This chapter serves as a technical support for the design primitives and applications for the next chapters. It describes a pneumatic platform that allows deforming a soft body and change stiffness of thin sheet (Ou, et al., 2014). Pneumatic actuation is chosen because air is a lightweight, compressible and environmentally benign energy source. A Pneumatic platform comprises with a combination of solenoid valves, a vacuuming and an inflation pump. They can be programmed to deform or change stiffness of a soft body. For this chapter basic concept and principle of how pneumatic control for defor-mation and jamming will be explained. In the next chapter I will describe the fabrication of the soft body, in which we can encode material distribution to archive desired trans-formation.

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Inspiring works

Soft RoboticsSoft robotics is an emerging domain that is dedicated to robots comprised of soft components including soft actuators, flexible sensor/circuits, and soft bodies. In contrast to other techniques for shape change, such as spatial arrangement of actuated modules, self-foldable chains, self-foldable surfaces, soft robotics often focus-es on pneumatic actuation of elastomeric channels and bladders. The elastomeric channels are designed in a way, so that when inflated, the soft body can perform a series of locomotion (Ilievski, Mazzeo, Shepherd, Chen, & White-sides, 2011).

While a primary focus of soft robotics is the improvement of the robot’s performance and the exploration of the bio-inspired mechanism itself, there is a large space to introduce soft robotic technology in constructing shape changing interfaces. One design space is to explore not

Figure 22. Multigait Soft Robot, Harvard Whitesides Group, 2011. The locomotion is enabled by the air inflation and deflation.

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only isotropic, but also anisotropic deformation with soft composite materials: an elastomer by itself deforms uniformly under stress; however, by compositing different structural layers with various mechanical properties, the orientation of deformation can be controlled. More detail will be explained in the coming Chapter.

Tunable-Stiffness With JammingStiffness-changing material and mechanism have been explored in mechanical engineering to construct robotic manipulators, such as medical robotics, gripping arms (Cheng. et al. 2012). Particle jamming has been explored recently. Granular jamming system can switch from fluid state to solid state when air pressure gets low. Externally actuated snake-like manipulators (i.e. those with actu-ators integrated into the structure) utilize this stiffness changing mechanism to deform and lock to different shape states.

Figure 23. Stiffness tunable material enabled by jamming. (a) Particle jamming for robotic gripper. (b) Layer jamming for robotic arm

a b

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However, particle jamming has unique disadvantage as it can only work in a relatively large volume system, thus it cannot be used to construct thin and light surface/wall with tunable stiffness. To solve this issue, layer jam-ming was developed very recently (Kim, Cheng, Kim, & Iagnemma, 2012). Layered jamming system includes an airtight envelope with multiple thin layer jamming flaps (i.e. sketch paper) inside. It utilizes a negative air pres-sure to amplify the friction between each jamming layer. Layer jamming has been used to construct the wall of robotic manipulators in hollow tubular shape, which can be deformed and actuated to grasp objects. Orthoses and protective equipment that can be shaped and fitted to the body shape in an optimal way have been developed

Principle of Layer-jamming

Layer-jamming systems can be composed of an airtight envelope with multiple thin layers of “flaps” (e.g., paper) inside. As with particle jamming, the system utilizes nega-tive air pressure to vacuum-pack the thin layers of material to amplify the friction between each layer. As illustrated in Figure 2, where S, P, n and μ represent the overlapped sur-face area, the pressure applied on the surface, the number of layers present, and friction coefficient of the thin layers respectively, the maximum resisting tensile force (F) can be calculated as follows:

F = μnPS.

Depending on the direction of applied external loads, the flexural stiffness of the jamming layers can also be im-portant. If the direction of an applied external force is not parallel with all the flaps, then the layered flaps can be subjected to bending forces. That is the reason why even sheet materials with high friction coefficients do not nec-

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Figure 24. Layer jamming effects are dependent on both maximum resisting tensile force and compressive bending force

essarily result in a layer-jamming system with significant bending stiffness.

Control system

Inflation for deformationTo deform a soft body, a large-sized stationary air com-pressor (Silent Aire Tech., Super Silent compressor 50) and a vacuum pump (Rocker Scientific, Oil-Free Pump 300) were used for experiments. However, typical tethered pneumatic systems with a stationary air compressor limits use in portable applications. Therefore, we developed a

miniature pneumatic control system with small solenoid

Figure 25. (a) Basic pneumatic circuit for single air bag; (b) Self-contained pneumat-ic system

a b

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valves (SMC, Series S070), a pump used as both supply and vacuum (Koge Electronics, Series KPV), and lithium polymer battery (3.7V, 110mAh). The system indicates feasibility of a further mobile application. The noise levels of the systems are 40dB and 72dB for the stationary air compressor and the miniature pump used in the portable in the portable system, respectively (catalog value).

Vacuum for JammingIn a jamming control system, air can be either vacuumed out of or pumped into the jamming envelope. A lay-er-jamming control circuit can be composed of two 3-port solenoid valves and one air pump for a single jamming envelope. For most of our tests and applications, we built a portable control system composed of an Arduino mini Pro, mini Arduino FET shield, SMC s070c-sdg-32 solenoid valves and AIRPO mini D2028 air pump (Figure 6b). There are three modes to control the airflow in and out of the layer-jamming envelope: exhaust, supply, and close.

The exhaust/supply is the mode to deflate/inflate an air bag, respectively. The close mode stops the airflow to maintain the system at a certain air pressure and therefore a degree of stiffness (Figure 26).

Figure 26. Layer-jamming control system: (a) Basic pneumatic circuit for single air bag; (b) Portable pneumatic system

a b

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For the deformable furniture application, a large station-ary vacuum pump instead of a small portable air pump is used, due to the large volume of air that needs to be removed for the application. The stationary version of the layer-jamming control system can achieve greater jamming and inflation speeds, as well as larger negative pressures when jamming. This is crucial since a higher jamming stiff-ness is desired for the furniture application.

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Proposed Design Space

Proposed here is a framework of constructing future shape-change interfaces. This approach looks at how can we shift our focus from programming the actuator (force) to the structure (material). Rather than repetitively patch-ing actuators (be it gear motors or smart materials) on the material, then connecting them to a global controller, we could also directly encode transformation information into the inert materials by controlling the material hetero-geneous distribution. The approach of encoding transfor-mation information in materials is called Programmable Material Anisotropy. By giving them different energy sourc-es (forces), they should accomplish a reversible shape-change as programmed.

As demonstrated in Chapter 3, material’s anisotropy can be utilized to archive complex transformation. However, programming materials anisotropy does not suggest giving up on programming the force. I also draw a spectrum of transforming forces: computational, manual, and environ-mental. Their controllability/programmability decreases in such order. This is another parameter of designing Mate-rial Transformation. Together with programmable material

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anisotropy, I outlined a design space in which materials’ transformation can be designed to meet different de-mands and applications.

This framework is both analytical and generative. Some of the existing works can fit into it. I attempt to complete the whole spectrum with either physical prototypes or design sketches. Hopefully it will server as an inspiration for new inventions for interfaces design.

Parameters

Deforming Forces

“The form of an object is a diagram of forces -- D’arcy Thompson”

From stones eroded by the wind; to human hands shaping materials into products; to motor-controlled high-preci-sion movement, all things change shape by the force that act upon it. A force shapes formation or transformation of physical matter.

In his book <On Growth and Forms>, D’arcy Thompson defined the abstract mathematical systems which underlie organic structural form and their transformations. (Thomp-son, 1992) Thompson sought to define form through the understanding of how physical forces produced structure and pattern. The attempt was to devise the underlying set of geometric laws, which shape form in relation to external force. Such force can be from external like wind, gravity or human intervention; or from internal like thermo, chemical forces. No doubt that force is a parameter of shape-change system. If we want to program transformation, we need to consider the programmability of the deforming forces. Ap-parently, the environmental forces, such as wind or gravity are difficult to be controlled.

Figure 27. The transformation of crustacean carapaces through the deformation of a flexible Cartesian coordiation

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Three types of deformation forces are introduced in this framework. They are

Computational force: External computationally controllable actuator connected to the materials causes their deforma-tion. Air pressure is selected in this thesis. It can be also hydraulic actuation or smart material such as SMA.

Manual force: Human body’s direct action upon the phys-ical materials causes their deformation. Such as bending, pressing, pushing, etc.

Environmental force: Natural forces acting upon physical materials cause their deformation. Such as gravity, wind, etc.

The rationale of such categorization is the programma-bility: how easy we can embed instruction in such force. The computational force can be precisely instructed as we programming in the microcontroller; Manual force can be controlled by our body, but not as precise as computation-ally control; The environmental force is the most difficult to be influenced. However, we can still control the materials transformation by programming material anisotropy. As

Figure 28. Three types of deforming Forces for designing transformable interfaces.

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mentioned, not only forces shape the structure of natural materials, but also, together the structure of materials, they can form unique transformation.

Programmable Material Anisotropy

“The book of nature is written in characters of geometry --Galileo”

As Neri Oxman suggested (Oxman, 2010), Nature’s ap-proach of creating maximum form diversity by using min-imum resources is through material anisotropy. Nature utilizes material anisotropy to achieve expressive forma-tion and transformation. Generally speaking, anisotropy is the property of being directionally dependent. It can be defined as a difference of material’s physical properties (stiffness, refractive index, density, etc.), when measured along different axis. It implies the ununiformed distri-bution of physical material that causes heterogeneous mechanical properties. As mentioned above, wood is a naturally anisotropic material. Its properties vary widely when measured with the growth grain or against it. That is why when dried, they deform in different orientation.

In the field of Material Science and Engineering, the con-cept of anisotropy is tightly linked to a material’s micro-structure defined by its grain growth patterns and fiber orientation. However, beyond such scales anisotropy can be utilized as a general design strategy for human-scale shape-change interfaces.

In this thesis, the material anisotropy is specified as the heterogeneous stiffness distribution, for the stiffness is more relevant to the physical transformation. When ex-ternal forces act upon the material, the stiffness of the material defined the degree of deformation. The stiffer the material is, the smaller the deformation is. If we can

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encode the stiffness distribution across the material, a desired transformation can be archive.

Two types of Programmable Material Anisotropy are de-fined here:

1. Anisotropy in Space: Encoded Stiffness DistributionThe material has different stiffness across the region.

For example, the material can be wood or paper, and the notches or indentations may be cut or engraved by a laser cutter to form a more flexible region. As “Programmable” indicated, three basic parameters of stiffness distribution are defined:

Location: controls where should deform;

Density: controls how much should deform;

Orientation: controls the direction of deformation.

2. Anisotropy in Time: Dynamic Tunable Stiffness

Unlike static pre-defined stiffness distribution, material’s overall stiffness can be dynamically controlled via the pneumatic system. This enables a dynamic transforma-tion. As explained in the last chapter, the parameter that is

Figure 29. Basic parameters of Programmable Material Anisotropy. (a) Location, (b) Density, (c) Direction.

a b C

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crucial to the stiffness changing in time is the negative air pressure in the jamming bag.

Design space

Once we have the parameters, we can now draw a design space for material transformation. By matching the De-forming Forces and Programmable Material Anisotropy together, we have six different type transformations, which can be programmed in different ways. They are:

i. Pre-defined Stiffness distribution with Computa-tional Deformation;

ii. Pre-defined Stiffness distribution with Manual Deformation;

iii. Pre-defined Stiffness distribution with Environ-mental Deformation;

iv. Dynamic Tunable Stiffness with Computational Deformation;

v. Dynamic Tunable Stiffness with Manual Deforma-tion;

vi. Dynamic Tunable Stiffness with Environmental Deformation;

Some of those transformations have been widely studied before or they have lower programmability. For example, Pre-defined Stiffness distribution with Manual Deforma-tion is about origami and foldable structure design, which has been studied quite widely. Their transformations do not response dynamically, neither.

Therefore in this thesis, I will focus on type B, D, E. I will

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Figure 30. A design space of transformable material for Shape Changing Interfaces.

also leave the type F in the future work due to complex-ity of conducting real-world experiment. For each type, I present series of transformation primitives to proof the concept.

Transformation primitives

Type A

Dynamic Tunable Stiffness × Manual Deformation

This material primitive examines at how a tunable stiffness would affect manual deformation of a thin sheet material. A tunable stiffness enables a dynamic material constraint when user manually deforms the interface. A user can easily change the shape of the interface when it is soft and quickly lock the shape by tune it to stiff.

Primitive A is a simple plan sheet with tunable stiffness.

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It contains 12 layers of 80-gram sketch paper. The figure 31 shows that as the air pressure inside the jamming bag drops, the sheet exhibits higher stiffness.

Primitive B looks at a weaving structure of two jamming sheets can determine the bending orientation of the wo-ven piece. We can weave multiple jamming units to modify the stiffness of layer jamming. In the test, we design a jamming unit, which has twelve layers of eight strips. By cross-weaving the two and applying different air pressures on each, we can define the directional bending behavior. When only vacuuming the horizontal jamming unit, the whole piece can be only bent up and down; when only vac-uuming the vertical one, the whole piece can be only bent left and right.

Figure 31. Dynamic Tunable Stiffness with Manual Deformation. The stiffness of the sheet varies as the negative air pressure changes inside the airtight envelop.

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Figure 32. Two jamming bags woven together. It constrain the bending direction, up / down or left / right.

Figure 33. Five jamming bags woven together. Each one can be individual controlled.

Alternatively, we can also add the stiffness control to each strip. Figure 33 shows a 5 by 5 weaving structure. Each strip’s stiffness can be tuned individually. The weaving structure enables a more free addressable control of sur-face stiffness.

We can envision that, with more sophisticated weaving structures or higher resolution of stiffness control, tunable stiffness would allow more type of interaction with physi-cal material be programmed or defined, such as the de-gree of rolling, the direction of stretching, etc. (Schumach-

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er, et al, 2010). Those interactions can be computationally enabled or constrained as the stiffness changes.

FabricationAll primitives are fabricated with heat seal machine. As figure 35 showed, two pieces of transparent vinyl were cut into the identical size. One of them has an air connector attached on. We sealed first three sides of the two vinyl pieces together. After that put the jammable materials in. They can be sketch paper, fabrics, cardboard or sandpa-per. A detailed performance comparison of those mate-rials can be found in the appendix. Finally we sealed the last side to create a completely airtight jamming unit.

Figure 34. Interactions with sheet shape material.

Figure 35. The fabrication process of stiffness changing sheet

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Figure 36. Structure of the composite

Type B

Pre-defined Stiffness distribution × Computational Defor-mation

These material primitives examine at how a pre-defined material stiffness distribution would affect computational controlled deformation. Here, an elastomer by itself de-forms uniformly under controllable air pressure; however, by compositing different structural layers, the orientation of deformation can be pre-defined.

Primitive C, This transformable primitive includes three layers, a silicon layer with embedded airbags connected with air channels, a paper layer with crease patterns, and a thin silicon layer at the bottom to bond and protect the paper layer. While soft actuators have been introduced before, this one focuses on introducing paper composite with various crease patterns to control the bending be-havior. When inflated, the inner airbags function as actua-tors to generate elongation and force the surface to bend towards the opposite direction.

In this case, dynamic control of the curvature is deter-

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mined by two factors: air pressure and crease pattern. First, airpressure can control the degree of curvature. Our experiments show how pumping additional air will make a single bending turn into a curling with continuous bend-ing. Secondly, the design of paper crease patterns will affect the deformation. As mentioned above, three param-eters of crease patterns are defined in the experiments: density, location and direction. Figure 37 also indicates how density affects the sharpness of bending. Lower density creases enable sharper bends and by varying the location of crease, we can control the bending location on the surface. Laying out the crease lines diagonally gener-ates helical shapes instead of curling on a single plane.

Wood has been also test in this experiment. Figure 38 demonstrates a variation of on-surface pattern cuts on thin pieces of wood instead of paper. It shows similar bending and curling behaviors.

To apply the aforementioned approaches of dynamic control of shape changing states, we test how specifically designed crease patterns and respective control of airbags can make a flat circular shape morph into different spatial structures with three stands (Figure 39). We also show a progressive transformation from a line to a square.

Figure 38. Crease patterns on thin wood.

Figure 37. The bending behavior changes as the lovation, density and direction of the crease pattern varies

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Figure 40. (a) Structure of composite material. (b) Fabric constraints of deformation in local areas of surface.

In Primitive D, the appearances of surface bumps are determined by air pressure and cut pattern. Elastic fab-ric (Spandex) was chosen due to its compliance under stress when composited with silicon. The difference in the Young’s Modulus of fabric compared with silicon creates multi-state deformation (Figure 40). We demonstrate that the same surface will deform from macro to micro level as air pressure is increased (Figure 41).

One advantage of a fabric-elastomer composite is the ease of designing and fabricating different patterns. Rather than making customized molds for textures, patterns can be quickly designed and cut with digital fabrication meth-

Figure 39. Specifically designed crease patterns and respective control of airbags enabling dynamic transformation of shapes.

a b

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ods, such as laser cutting. Figure 14 shows a variety of texture patterns we have explored.

Alternatively, the surface of a multi-state shape change may comprise more than three layers. For example, the surface may comprise a “sandwich” of four elastic layers. A first central layer of the “sandwich” may be stiffer than a second central layer of the “sandwich”, and both central layers may be stiffer than the inner and outer layers of the “sandwich”. Holes in the second central layer may be surrounded by holes in the first central layer (when viewed from a perspective normal to the central layers). This four-layer “sandwich” can produce at least three levels of bumps. For example, during an initial stage of inflation of the multi-state inflatable device, the overall shape of the display may have only a single bump. In a later stage of inflation, a second level of bumps may form on the ini-tial single bump. During an even later stage of inflation, a third level of bumps may form on the second level of bumps.

Figure 41. (a) As the increase of air pressure, the surface deform from global to local region. (b) Different textures are generated due to different cut patterns on the fabric composite layer.

a

b

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Beyond bending or surface texture, we can envision a ba-sic syntax of shape-change (Rasmussen, et al., 2012) can be achieved just by the encoded material constraints. We can also envision that by combining syntax together, we may be able to create a more complex transformation with less actuator.

Figure 44. A syntax of shape changing.

Figure 42. multiple “sandwich“ structure.

Figure 43. Visualization of three-stages inflation.

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FabricationThe fabrication process of these primitive are molding and casting. The major soft body is molded and casted with Silicone Rubber ((EcoFlex 00-30, Smooth-on, Inc). All prim-itives are layered composite materials. In order to create a nicely performed composite, we used oven to accelerate the curing process of Silicone Rubber. After pouring the liquid Silicone Rubber in the mold, we put it in the oven for 10 minutes. It becomes solid but still not completely cured. We can then put another half-cured piece on top of it to let them bond naturally in the oven for 2 hours. Since paper cannot bond with Silicone Rubber, we coated the whole surface of the paper with the same type of Silicone Rubber so that it can bond with the air bladder.

Figure 45. Fabrication process

Figure 46.Molding & casting for Primitive C

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Type C

Dynamic Tunable Stiffness × Computational Deformation

As I showed in Type B, A pre-defined structure can support a two-stages shape-change. In this part, I exam a hypoth-esis with a sketch, that a tunable stiffness as a material constraint could support a multi-stages shape-change.

Here, a weaving structure of jamming is composite to-gether with an airbag. By tuning the stiffness at certain regions, the surface can deform differently each time we inflate the airbag.

The Primitive E is to be implemented in the future work.

Figure 49. Reversible multi-stages transformation.

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APPLICATIONS AS EVALUATION

“As structural, chemical and computational properties are integrated at nano-, micro- and macro-scales, even the

most traditional material might become dynamic. — Ramia Mazé”

No technological exploration is complete without real world application that can give form to abstract frame-work, push the limits of what is technically feasible today and how can it make send to people’s imagination. With that in mind, I have developed three application proto-types: HelighX, PLYABLES, and JamBot. Each focuses on one transformation type that I outlined in the previous chapter, respectively Pre-defined Stiffness distribution with Computational Deformation and Dynamic Tunable Stiffness with Manual Deformation. These application prototypes serve as the evaluation of the Material Trans-formation framework from last chapter, where I mentioned that the framework could be used as a generative source to create real-world applications.

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Design Principles

There are two design principles in designing these two applications.

1. Combining material anisotropy and computational con-trol.

Material constraints can be either pre-programmed stiff-ness distribution, and/or real-time tunable stiffness; com-putational control can be shape-changing actuation and/or stiffness-changing control. As a proof of the framework, the application should demonstrate that by programming material anisotropy, we could archive an expressive trans-formation that facilitates new type of interaction.

2. Combining sensing capability and output in a form of properties changing.

As an interface, it must be able to take input directly from outside world and response with its physical property changing. As this thesis focuses on shape transformation, the sensors are directly patched in/on the transformable material. In the future, I will look at how to integrate sens-ing and actuation as a single material.

HelighX: Shape-shifting Lamp

DesignThis lamp supports large deformation from a straight strip shape to a rounded bulb shape. Users can pull the strip like pulling the chain of a conventional lamp. The strip is the illuminating light itself and it starts to curl and light up. This demonstrates Shape-changing combined with optical properties (Figure 50).

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Sensing

Soft robotic engineers have shown how to construct elas-tic sensing surfaces by injecting conductive liquid metal (eGaIn) into inner channels of elastomer [1]. The resistance of liquid metal changes in response to the deformation of the channels (Coelho, 2008).

Figure 50. (a, b) Lamp in straight state capable of user input by pulling the entire body. (c) Silicon with embedded liquid metal as pulling sensor. (d, e, f, g) Lamp in bulb state by curling.

Figure 51. The resistance of liquid metal sensor changes in response to the deforma-tion of the elastomeric channels through pulling.

a b c d

e f g

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We adapt this sensing technique to fabricate the top layer of the composite material. It can sense surface deforma-tion through both direct manipulation and air actuation. These conductive channels can also be used for capacitive sensing to detect human touch.

FabricationThe construction of the lamp is inspired by one type of shape changing primitives: the curling behavior under cur-vature change on surfaces. Silicon with embedded liquid metal is fabricated as pulling sensor, which is attached to the top of the lamp stip. Soft lithography is adapted for fabricating the shape-shifting lamp. Before the casting process, surface mounted LEDs are soldered on top of flex-ible copper strips. We then bond the copper strips with a paper substrate with angular cut patterns. The two layers, paper layer and air channel layer, are bonded together with half cured silicon.

PLYABLES: A Deformable Furniture

DesignWe design a portable chair that resembles a flat, flexible carpet in its unjammed state, such that it can be folded and carried easily . When users transform the flat sheet

Figure 52. The Expanding Geodesic Dome by Hoberman Associate. 1991

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into the shape of a chair by creating two folds where the sensors are embedded, the system will automatically start the jamming process after three seconds. Once jammed, the carpet will become stiff enough to maintain the chair shape and support up to a load of up to 55 kilograms. The carpet can be formed into other 3D shapes as well, such as a table board, or a free-formed lounge.

Sensing PLYABLE can be embedded with sensing layer. In order to

Figure 53. Deformable Furniture: (a) Unwrapping a flexible carpet. (b) Vacuuming the carpet. (c) Carpet becoming stiff. (d) Carpet becoming soft again and conformed to the shape of the box. (e) Carpet turning into a chair. (f) The chair holds weight up to 55kg.

Figure 54. Deformable Furniture: (a) Unwrapping a flexible carpet. (b) Vacuuming the carpet. (c) Carpet becoming stiff. (d) Carpet becoming soft again and conformed to the shape of the box. (e) Carpet turning into a chair. (f) The chair holds weight up to 55kg.

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proof the concept, a serial of prototypes have been made. The way to construct thin pressure and bending sensors with off-the-shelf materials has been introduced. We construct our pressure sensor and bending sensor with one layer of copper tape, one layer of 3M velostat, and another layer of copper tape. As the sensor are pressed or bent, the copper tapes will make more contact with the velostat. Thereby the electrical resistance between the three layers will be reduced. This behavior allows us to detect the amount of force applied on the sensor. In our material samples, pressure sensors are constructed as round shapes and can be attached to any area that need pressure detection (Figure 54a-c).

Bending sensors are constructed in rectangular shapes and can be attached to the hinges at which bending needs to be detected (Figure 54d-f). As a preliminary exploration, our current sensors have discrete sensing points. In the fu-ture, a more generic sensor network can be constructed as

Figure 55. Embedding sensors in the jamming units: (a-c) pressure; (d-f) Bending; (g-i) Mutual capacitance.

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well. For example, instead of four pressure sensor points, the entire layer can sense pressure at any given point.

Mutual capacitive sensing is also explored as an approach to detect proximity between two folding surfaces (Figure 54g-i). Similar to bending sensors, we can also construct a more complex sensing network to detect more complex shape deformation.

FabricationWe use 25 layers of 800-grit sand paper as jamming flaps to build the entire jamming unit. Each flap has a dimen-sion of 45 × 152 cm. The total thickness of the unit is 8.5 mm. For the jamming envelop, we use a heat sealable 70 Denier Nylon Taffeta fabric (rockywood.com). It is a nylon fabric, which has PVC laminate on one side, which pro-vides the possibility to heat seal. The Nylon fabric pro-vides nice visual aesthetic and smooth haptic sensation. The sealing processing is similar to the primitives as de-scribed above. We added one layer of mesh fabric to help the air flow evenly, as the jamming surface is much bigger than the primitives.

Figure 56. Flexible arm cast.

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Extension of applicationBased on the similar fabrication process, we build anoth-er strip whose stiffness can be also dynamically tuned. The strip has a dimension of 10 *120 cm. It is designed as a reconfigurable rehabilitation cast. Patient can wrap it around neck, arm or leg when need. The strip can change its stiffness through time as the patient recovers.

JamBot

DesignTo demonstrate the potential of combining Dynamic tun-able Stiffness and the computational controlled actuation, we built a soft robotics that can change its stiffness. The robot can crawl across the floor like other soft robot when it is soft. After jamming, its body stiffens to resist higher pressure or load. For this prototype the jamBot can take about 400 grams vertical load. (Figure 57)

The design of the jamBot is inspired by the deep-sea ani-mal sea cucumber. It is an echinoderm that can change its skin stiffness to resist under water storm. We envision that

Figure 57. JamBot uses pneumatic actuation

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Figure 58. The robotics increases its stiffness to take more load

the future stiffness-changing robot can be use for rescue in disaster.

Sensing and motion controlTwo electrodes are embedded on the back of the jamBot. They can sense human’s touch as a trigger of stiffening. The motion control system includes a jamming and an inflating system (see chapter 4). As current prototype is limited by its own dimension, we did not attach the whole control system on the soft body.

FabricationThe jamBot has a dimension of 0.5 by 5 by 25 cm. It com-prises with two layers: a jamming layer and an actuation

Figure 59. The control and pneumatic circuit.

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Figure 60. Surface bending can be determined by the compression of airbags with low elasticity.

layer. Two layers are glued together by common super glue. The jamming layer contains 18 layers of sand paper. The ends of the sand papers were cut into a structure to archive high flexibility. The actuation layer includes two non-flexible airbag. While inflated, the airbags behave like the biceps (the muscle to pull the arm up), and compress-es themselves to cause the jamming layer to bend. The inflation of non-elastic airbags happens on the same side as the surface bends towards (Figure 60). For more infor-mation about compression for bending, please refer the paper. (Yao, et al., 2013)

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A STEP FORWARD...

Morphing Vehicle

If we utilize Programmable Material Anisotropy as one parameter of designing future transformable object, we might then be able to rethink some of the big (both scale and technical wise) design challenge in the real-world applications of transformable material. Morphing Wings have been on the top list of future transformable objects. The development of morphing wings can potentially en-hance the aircraft maneuver. For example, the wing twist could be adjusted throughout the entire flight in order to maintain a shape giving optimal lift-drag ratio for max-imum range. It could be also as a means of roll control.

Figure 61. The concept drawing of morphing wings

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If we could utilize material with Dynamic Tunable Stiff-ness to construct the wings, we could possible leave the shape-change task to the environmental wind, let it form the wings to a desired shape as we adjusting its stiffness. Similarly, we could adopt this approach to design trans-formable car or sail. This is the Type F transformation that described in chapter5.

Beyond transformation

Previous chapters demonstrated that programming mate-rial anisotropy in space and time provides an alternative way of designing Material Transformation in the context of HCI. Yet the full potential interpretation of anisotropy as a method of controlling material organization remains still less explored for interface designer. In the field of Material Science, engineers find inspiration from natural anisotropy to design new smart material that can dynamically change properties in response to manual deformation (figure 62). It is therefore crucial for interface designers to adopt the concept of designing anisotropy across scales to fully discover the potential of new actuators, smart materials or sensors.

Through this thesis, I hope to inspire designer to look at interaction design from a material perspective. As Neri Oxman stated: “ anisotropy is without a doubt one of the

Figure 62. Material properties.

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most important properties for a designer operating at the heart of contemporary design culture. “ Beyond Material Transformation, what else can we do with Programmable Material Anisotropy?

IlluminationIn HCI, illumination is usually designed with electronic components such as LED or light bulb. Inspired by the work from Matthias Kohl, we could also design illumina-tion change by designing dynamic material anisotropy change. Another of my on-going project optiElastic looks at how can we fabricate multi-layer elastic optical wave-guide with elastomers, which have different refractive index. Such layered structure allows guiding a certain wavelength, red for example. When stretched, however, it guides another wavelength, green for example. The color change needs no longer electronic I/O transducer, but just the material’s structure change.

SensingAs interface designers are increasingly encountering new type of sensors to build novel applications, how can one design with it beyond simply patching it? Again, we can look at how the distribution of the sensor can be designed

Figure 63. Customized elastomeric waveguide with cladding.

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in response to human input. For example, we can embed a type of touch sensor on an elastomeric surface, so that when user stretch the surface, the gap between the sen-sors would change to facilitate another sensing modality (from swipe to precise touch).

Construction The future of constructing physical world lies in the smart-er material, not just smarter machines. If we could design material parts with a programmed heterogonous structure, so that we could assemble them in a particular sequence, we could create a macro-scale material that can perform self-assembly. Inspired by how DNA performs self-as-sembly in the cell, Skylar Tibbits provides an approach of embedding assembly information in the material. He de-signed material part based on the computer logic so that then can self-assemble to a desired shape under a passive force. (Tibbits, 2010)

Figure 64. Visualization of deformabale sensor. Sensing modality changes from (a) swiping to (b) accurate selecting.

Figure 64. Digital simulation of Logic Matter self-assembling to a sphere.

a b

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Nano-Actuator DistributionIt has been shown in earlier work (Chen, 2014) that the Bacillus subtilis spore can be used to bend and release a thin sheet substrate, due to this spore’s hygromorphic be-havior. Inspired by these results, we could also introduce the anisotropy to the deposition of those nano actuators onto substrate geometries to achieve a wide variety of shape transformations. Orientation of spore deposition define the orientation of bending, position defines loca-tion of bending, and density defines degree of bending. By combining different parameters, we can achieve finely tuned curvatures on thin strips and larger surfaces.

Figure 63. (a) SEM scanning of bacillus subtilis natto spores applied on a latex substrate. (b) Bacillus Subtilis Natto under microscope.

Figure 63. (a) Controlling the final bending curvature by depositing spores with different densities. (b) Bending in different orientations defined by the orientation of lines printed out of Bacillus spores.

a b

a

b

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CONCLUSION

Physical transformation is by no mean new idea in HCI, but it remains largely unexplored due to its technical challeng-es and scalability. Inspired by how natural material chang-es shape based on its microstructure, this thesis takes a material perspective on designing transformable interfac-es. The structure of material and mechanical properties such as stiffness, can not only determine its static perfor-mances, but also, with the help of external forces, support dynamic shape change.

By introducing Programmable Material Anisotropy into the design process, the thesis aims to contribute an alterna-tive way of prototyping shape-change interfaces, which exhibits expressive property-change, in an ecological and rapid way. We could partially offload the shape-changing control from actuators (digital) to the material itself (ana-logue), to achieve more types of shape-change that cur-rent modularized actuation system cannot easily do.

As contribution, the thesis explores:

1. An integrated framework of designing shape-change interfaces. Material anisotropy should be added

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to the agenda of designing shape-change interfaces in Human-Computer Interaction (HCI). It could help us build expressive transformable objects more easily.

2. A pneumatic actuation platform that allows ma-terial change shape and stiffness.

3. Application prototypes show how transformable material can be used in everyday life.

4. Provide a material perspective for interface de-signer to play with smart materials beyond shape-change. The old “patching” approach leaves designer little space for creation. By introducing programmable anisotropy, de-signers could maximize the creativity with limited technol-ogy.

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APPENDIX

Jamming evaluation

Based on the aforementioned calculation of layer jam-ming’s maximum resistance to tensile loads, stacking-layer materials with high friction coefficients can achieve a higher stiffness while the system is jammed. However, some materials, which have high friction coefficients, cannot achieve a considerable stiffness when jammed due to their own softness. Therefore the material selection is not trivial anymore. For this paper, we have surveyed 32 types of thin sheet materials (Figure 13) that are that are relatively inexpensive, commercially available materials, and conducted bending torque comparison tests between normal and jammed states to quantify a material’s stiff-ness change. The purpose of this test is to provide design-ers and researchers with an overview of what materials are suitable for layer jamming and to compare and extrapolate relevant and desirable properties (thickness and weight) for different applications.

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Figure 14 shows the test setup. A standard layer-jamming test sample is 12 flaps of targeted materials (20cm by 20cm) sealed in Vinyl-Pane clear plastic (Warp Bros). In the test, we bend a test sample from 0° to 30°. The lever arm is 15.2 cm. Based on the measured bending force, the bending stiffness (jammed or unjammed state) of a sample can be roughly calculated as: torque = 0.152 × F × sin30º, where F is the measured bending force.

Figure 15 and 16 present examples of the normal and jammed bending torque ratios of five types of materials as a function of weight and thickness, respectively. As indicated in figure 17, we have also tested the bending stiffness changes based on the change in air pressure in

Figure 67. Samples of materials tested for layer jamming

Figure 68. Test setup of jamming samples’ torque

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the jamming envelope in order to understand how the neg-ative air pressure influences the jamming performance. These graphscan be useful for designers to select jamming materials based on thickness and weight criteria.

Figure 70. Materials’ distribution in thickness and torque.

Figure 69. Materials’ distribution in weight and torque.

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BIBLIOGRAPHY

Addington, M., & Schodek, D., (2005). Smart Materials and Technologies for the architecture and design profes-sions. Burlington, MA, Architectural Press.

Ahlquist, S., Menges, A., (2011). Computational Design Thinking. London, UK, Wiley Publication.

Chen, X., Mahadevan, L. Driks, A and Sahin O. Bacillus spores as building blocks for stimuli-responsive materi-als and nanogenerators. Nature Nanotechnology 2014, 9, 137–141.

Cheng, N.G., Lobovsky, M.B., Keating, S.J., Setapen, A.M., Gero, K.I., Hosoi, A.E., and Iagnemma, K.D. Manipula-tor Enabled by Jamming of Granular Media. ICRA (2012), 4328–4333.

Coelho, M., Ishii, H., and Maes, P. Surflex: a programmable surface for the design of tangible interfaces. In CHI EA ’08, ACM (2008), 3429-3434.

Ilievski, F., Mazzeo, A.D., Shepherd, R.F., Chen, X., & Wh-itesides, G.M. Soft robotics for chemists. Angew. Chem.Int. Ed., 50, 8 (2011), 1890–1895.

Ishii, H. 2008. Tangible bits: beyond pixels. In Proceed-ings of the 2nd international Conference on Tangible and Embedded interaction (Bonn, Germany, February 18 - 20, 2008). TEI ‘08.

Ishii, H., Lakatos D., Bonanni L., & Labrune. J.B. (2012). Radical atoms: beyond tangible bits, toward transformable materials. interactions 19, 1 (January 2012), 38-51.

92

Kim, Y., Cheng, S., Kim, S., and Iagnemma, K. Capability by Layer Jamming. IROS ’12, IEEE/RSJ (2012), 4251–4256.

Kolle, M. (2011). Photonic Structures Inspired by Nature (Doctoral thesis).

Menges, A., & Reichert, S. (2012). Material Capacity, Embedded Respoinsiveness. Architechtural Design, 2012 March, p52-59.

Niklas, K. J. (1992). Plant Biomechanics: An Engineering Approach to Plant Form and Function. Chicago & London, The University of Chicago Press

Ou, J., Yao, L., Tauber, D., Steimle, J., Niiyama, R. & Ishii, H. jamSheets: thin interfaces with tunable stiffness enabled by layer jamming. In TEI ‘14, 65-72.

Oxman, N., (2010). Material-based Design Computation (Doctoral thesis)

Rasmussen, M., Pedersen, E., Petersen, M., & Hornbæk, K. Shape-changing interfaces: a review of the design space and open research questions. In CHI ’12, ACM (2012), 735–744.

Schumacher, M., Schaeffer, O., Vogt, M.M., (2010). MOVE: Architecture in Motion - Dynamic Components and Ele-ments. Basel, Switzerland, Birkhaeuser Verlag.

Thompson, D., (1992). On Growth and Form. Cambridge, UK, Cambridge University Press

Tibbits, S., (2010). Logic Matter: Digital Logic as Heuristics for Physical Self-Guided-Assembly (Master Thesis).

Weiser, M., The computer for the twenty-first century. Sci-entific American. v265 i3. 94-104.

93

Yao L., Niiyama., Ou J., Follmer S., Silva C., & Ishii H., PneUI: Pneumatically Actuated Soft Composite Materials for Shape Changing Interfaces. UIST’13, ACM Press (2012), 13-22.