Mechanical behavior in interactive systems is typically fixed at fabrication through geometry and material selection. This paper introduces GrowMechanics, a Research-through-Design fabrication approach that explores mechanical design through biological growth rather than predefined specification. Positioning growth as a temporal design parameter and a form of material computation, we investigate how mechanical behavior can evolve over time through living processes. Our exploration centers on a living biohybrid joint fabricated by growing bacterial cellulose between porous scaffolds. The joint serves as a research probe to examine how sequential fabrication, through staged growth and intervention, shapes mechanical behavior. We identify consistent tendencies in growth-driven stiffness variation and flexible geometry matching, alongside structured, geometry-dependent responses that arise from the material’s hydrated and compliant nature. Thus, this work highlights a space of constrained predictability in growth-based mechanics, identifying factors that condition mechanical response and contributing design knowledge for HCI on how such behavior can be shaped through living fabrication.

Designers have long relied on steam bending, lamination techniques, kerf cuts, and considerable craft to shape curved wood. What if wood could be programmed to shape itself beyond bending, making complex forms more affordable? We present a computational framework for 3D printing wood-based hygromorphic structures that morph from initially flat sheets into two distinct doubly curved, non-developable surfaces upon hydration and dehydration. Our tool supports both forward and inverse design: starting from primitives or a target geometry, it generates deposition toolpaths and predicts wet and dry states. We characterize anisotropic swelling and shrinkage to calibrate the simulator and evaluate accuracy via corresponding point-pair distances on simulated and printed forms. Finally, we present primitive-based designs and three application demonstrations using our framework. By coupling material behavior with design intent on consumer-grade printers, our framework reduces skill and equipment barriers and enables new fabrication and design possibilities in wood-based practice.

We introduce DuoMorph, a design and fabrication method that synergistically integrates Fused Deposition Modeling(FDM) printing and pneumatic actuation to create novel shape-changing interfaces. In DuoMorph, the printed structures and heat-sealed pneumatic elements are mutually designed to actuate and constrain each other, enabling functions that are difficult for either component to achieve in isolation. Moreover, the entire hybrid structure can be fabricated through a single, seamless process using only a standard FDM printer—including both heat-sealing and 3D/4D printing. In this paper, we define a design space including four primitive categories that capture the fundamental ways in which printed and pneumatic components can interact. To support this process, we present a fabrication method and an accompanying design tool. Finally, we demonstrate the potential of DuoMorph through example applications and performance demonstrations.

In our everyday eating habits, we benefit from the diverse properties of natural food ingredients, from their taste and aroma to their texture. To further expand this potential, we draw inspiration from architected materials, in which engineered structures impart new mechanical properties. Building on this idea, we introduce kirigami and origami structures into fresh ingredients to embed new functionalities. Our design tool let users create custom, interchangeable rollers that apply cuts and folds to thinly sliced ingredients. By combining different structures with the inherent properties of food, users can transform everyday eating experiences across various contexts. To support users, we share experimental results with example ingredients to help them identify appropriate design parameters. Finally, we present several exemplar concepts in a recipe-style format to illustrate new interaction possibilities enabled by our reproducible fabrication pipeline.

Compliant mechanisms enable the creation of compact and easy-to-fabricate devices for tangible interaction. This work explores interconnected compliant mechanisms consisting of multiple joints and rigid bodies to transmit and process displacements as signals that result from physical interactions. As these devices are difficult to design due to their vast and complex design space, we developed a graph-based design algorithm and computational tool to help users program and customize such computational functions and procedurally model physical designs. When combined with active materials with actuation and sensing capabilities, these devices can also render and detect haptic interaction. Our design examples demonstrate the tool's capability to respond to relevant HCI concepts, including building modular physical interface toolkits, encrypting tangible interactions, and customizing user augmentation for accessibility. We believe the tool will facilitate the generation of new interfaces with enriched affordance.

We distilled a set of core practices within “morphing matter” research, derived a set of underlying skills and values, and developed these into a weekend workshop for high-school students. Participants in our workshop sampled a variety of research processes, including materials science and contextual design, incorporating curriculum-appropriate learning goals, toward an integrated pneumatic fashion project. We describe our approach, activity plan, and assessment as well as opportunities for research as an educational template to push beyond current “STEAM”-based educational practices for cross-disciplinary engagement.

While there has been sustained interest in shape-changing materials and deployable structures, many existing systems require engineering materials, precision fabrication, and computationally modeled kinematics in order to work. Additionally, many rely on external power sources in order to deploy. In light of these factors, we perceive a need for deployable materials that are easy to design, prototype, and deploy, and that can transform themselves in response to environmental stimuli, making them appropriate for ecological applications. In this paper, we present ExCell, a DIY-able system of water-responsive wooden linear actuators for self-actuating deployable structures. We show that ExCell can be used to develop a wide range of geometries, we present a prototyping method that can create accurate models of ExCell structures, and we suggest four possible applications for this system.

We print wax on the paper and turn the composite into a sequentially-controllable, moisture-triggered, rapidly-fabricated, and low-cost shape-changing interface. This technique relies on a sequential control method that harnesses two critical variables: gray levels and water amount. By integrating these variables within a bilayer structure, composed of a paper substrate and wax layer, we produce a diverse wax pattern using a solid inkjet printer. These patterns empower wax paper actuators with rapid control over sequential deformations, harnessing various bending degrees and response times, which helps to facilitate the potential of swift personal actuator customization. Our exploration encompasses the material mechanism, the sequential control method, fabrication procedures, primitive structures, and evaluations. Additionally, we introduce a user-friendly software tool for design and simulation. Lastly, we demonstrate our approach through applications across four domains: agricultural seeding, interactive toys and art, home decoration, and electrical control.

Feeling breath signals from the digital world has many values in remote settings. These signals have been visually or audibly represented in previous research, but recent advances in wearable technology now enable us to simulate breath signals via haptics, as an intimate and intuitive form of non-verbal interaction. Prior works relied on low-resolution methods of breath signal rendering and thus a limited understanding of associated haptic perceptions. Addressing this gap, our research introduces breatHaptics, a wearable that offers a high-resolution, haptic representation of breath signals. By utilizing extracted breath data, a mapping algorithm model and finely-tuned soft actuated materials, we deliver a granular simulation of human breath. Through a perception study involving force discrimination testing and haptic experience evaluation, we demonstrate breatHaptics’ ability to create a rich, nuanced tactile sensation of feeling breath haptically. Our work illustrates the promising role of breatHaptics as part of wearable technologies in offering well-being support.

While it seems counterintuitive to think of degradation within an operating device as beneficial, one may argue that when rationally designed, the controlled breakdown of materials— physical, chemical, or biological—can be harnessed for specific functions. To apply this principle to the design of morphing devices, we introduce the concept of "Degrade to Function" (DtF). This concept aims to create eco-friendly and self-contained morphing devices that operate through a sequence of environmentally-triggered degradations. We explore its design considerations and implementation techniques by identifying environmental conditions and degradation types that can be exploited, evaluating potential materials capable of controlled degradation, suggesting designs for structures that can leverage degradation to achieve various transformations and functions, and developing sequential control approaches that integrate degradation triggers. To demonstrate the viability and versatility of this design strategy, we showcase several application examples across a range of environment conditions.

Contemporary human-food interaction design is often a technology-driven endeavor in which food's materiality has been largely underexplored. Building on the concept of “computational food”, this paper explores the design of food as a material realization of computation through a material-centered approach. We engaged with a “Research through Design” exploration by designing a computational food system called “Dancing Delicacies”, which enables food items to be “programmed” and “reconfigured” within dynamic trajectories. Our practice led to a design framework resulting in four original dish designs. Our dishes aim to illustrate the richness of this new design space for computational food. Furthermore, through engaging with expert practitioners from the hospitality industry, we provide a first account of understanding the design of computational food for dynamic dining trajectories and its speculative use contexts in the industry. With this work, we hope to inspire researchers and designers to envision a new future of human-food interaction.

We present FlexTure, a method for creating pop-up kirigami structures with a selectively bonded bilayer. These surfaces enable a new design space for accessible and rapid prototyping of dynamic surfaces. Using a flexible material selectively attached to a stretched substrate, we can create metamaterial surfaces that change texture. The tactile and aesthetic effects of these surfaces can be tuned through the configuration of cuts in the top layer of material, as well as the selection of the layers themselves. We provide a design workflow and accessible methods to achieve target effects and experimentally measure some mechanical properties of the surfaces. Several application concepts are offered along with a computational design tool.

Computational mediation can unlock access to existing creative fabrication tools. By outfitting an otherwise purely mechanical hand-operated knitting machine with lightweight sensing capabilities, we produced a system which provides immediate feedback about the state and affordances of the underlying knitting machine. We describe our technical implementation, show modular interface applications which center the particular patterning capabilities of this kind of machine knitting, and discuss user experiences with interactive hybrid computational/mechanical systems.

We propose an approach to enabling exploratory creativity in digital fabrication through the use of grain spaces. In material processes, “grain” describes underlying physical properties like the orientation of cellulose fibers in wood that, in aggregate, affect fabrication concerns (such as directional cutting) and outcomes (such as axes of strength and visual effects). Extending this into the realm of computational fabrication, grain spaces define a curated set of mid-level material properties as well as the underlying low-level fabrication processes needed to produce them. We specify a grain space for computational brioche knitting, use it to guide our production of a set of hybrid digital/physical tools to support quick and playful exploration of this space’s unique design affordances, and reflect on the role of such tools in creative practice.

AI-based design tools are proliferating in professional software to assist engineering and industrial designers in complex manufacturing and design tasks. These tools take on more agentic roles than traditional computer-aided design tools and are often portrayed as “co-creators.” Yet, working effectively with such systems requires different skills than working with complex CAD tools alone. To date, we know little about how engineering designers learn to work with AI-based design tools. In this study, we observed trained designers as they learned to work with two AI-based tools on a realistic design task. We find that designers face many challenges in learning to effectively co-create with current systems, including challenges in understanding and adjusting AI outputs and in communicating their design goals. Based on our findings, we highlight several design opportunities to better support designer-AI co-creation.

Although fluidic computation has been utilized to develop interactive devices in the field of Human-Computer Interaction (HCI), the limited computation complexity of previous work hinders the exploration of richer interaction modalities. Based on the Fluidic Computation Kit we developed, this paper explores how unconventional mechanical computing can be leveraged to design shape-changing interfaces that integrate input sensing, output, and complex computation. After introducing the design space enabled by the Kit, we explain how to design four types of elementary computational components and six categories of operators. We end by providing several application scenarios which illustrate the Fluidic Computation Kit’s potential to build sophisticated circuits (e.g., a parallel processor) for use in the field of HCI.

Smart shape-changing materials can be adapted to different usages, which have been leveraged for dynamic affordances and on-demand haptic feedback in HCI. However, the applicability of these materials is often bottlenecked by their complex fabrication and the challenge of programming localized and individually addressable responses. In this work, we propose a toolkit for designing and fabricating programmable morphing objects using off-the-shelf epoxies. Our method involves varying the crosslinker to epoxy resin ratio to control morphing temperatures from 40 ℃ to 90 ℃, either across different regions of a shape memory device or across devices. Functional components (e.g., conductive fabric, magnetic particles) are also incorporated with the epoxy for sensing and active reconfiguration. A toolbox of fabrication methods and a primitive design library are introduced to support design ideation and programmable morphing. Finally, we demonstrate application examples, including morphing toys, a shape-changing input device, and an active window shutter.

While the majority of pneumatic interfaces are powered and controlled by traditional electric pumps and valves, alternative sustainable energy-harnessing technology has been attracting attention. This paper presents a novel solution to this challenge with the development of the Sustainflatable system, a self-sustaining pneumatic system that can harvest renewable energy sources such as wind, water flow, moisture, and sunlight, convert the energy into compressed air, and store it for later use in a programmable and intelligent way. The system is completely electronic-free, incorporating customized energy harvesting pumps, storage units with variable volume-pressure characteristics, and tailored valves that operate autonomously. Additionally, the paper provides a design tool to guide the development of the system and includes several environmental applications to showcase its capabilities.

The emergence of living organisms as entities in HCI presents an opportunity to collaborate with other beings through technology, align interspecies motives, and nurture greater empathy for the non-human. Plants are particularly interesting because of their natural ability to sense and respond to environmental stimuli and potential to enable more sustainable interaction design. However, due to the cross-disciplinary and emerging nature of this space, there is a need to identify overarching patterns and discern opportunities for unifying future research. This paper aims to systematically analyze existing Human-Plant Interaction (HPI) works by presenting a survey of projects across HCI, art/design, architecture, and bioengineering. We identify core design paradigms along the dimensions of HPI System Architecture, Plant I/O Coupling, Plant Interfacing and Manipulation Techniques, Application Context, and Scale. From these themes, we assemble a framework for HCI practitioners to approach HPI, and discuss opportunities and open questions for future exploration.

Seagrass meadows are twice as effective as forests at capturing and storing carbon, but human activities have caused them to gradually disappear over the last few decades. We take a nature-centered design approach on contextual inquiry and collaborative designs methods to consolidate knowledge from marine and material sciences to industrial design. This pictorial documents a dialogue between designers and scientists to co-create an ecological intervention using digital fabrication to manufacture morphing ceramics for seagrass meadow restoration.

Morphing Matter (MM) is a multidisciplinary field that combines material science and digital fabrication to create shape-changing and dynamic interfaces.In this workshop, participants will investigate ways in which MM tools can effectively support building STEM learning toolkits for novice learners from diverse backgrounds.Participants will engage in hands-on activities designing and simulating water-triggered morphing artifacts using a software design tool and fabricating them with low-cost materials.This workshop aims to collectively explore creative opportunities and barriers o introducing emerging STEM concepts and skills to novice learners.We hope to ideate frameworks for designing educational toolkits which leverage the accessible nature of morphing beads, democratizing a process that would typically require advanced material synthesis and specialized lab settings.Designers, educators, learning scientists, and researchers are welcome to join us in brainstorming ways to develop toolkits to support creative exploration in education with MM.

Morphing Matter (MM) is an emerging multidisciplinary field that combines material science and digital fabrication. It empowers people to engineer materials that respond to a specific energy or stimuli and transform its shape or other characteristics such as stiffness, opacity, and phase. This poster introduces creative pathways with MM to engage girls in science, technology, engineering, and mathematics (STEM) learning, sparking interest in the field. We share our experience designing a set of learning tools that introduce novices to MM by fabricating morphing artifacts triggered by water. Further, we present a pilot MM workshop highlighting our reflections on designing learning experiences to foster high-school-aged girls' curiosity and interest in STEM.

The field of Morphing Matter (MM) is often associated with high-tech equipment or inaccessible lab environments. In this work, we explore morphing matter applications within the context of DIY craft, showcasing different actuation methods for morphing artifacts created using compact, inexpensive, and easily replicable toolkits. This demo presents three morphing matter toolsets that enable novice learners to design shape-changing food, artistic figurines that transform underwater and inflatable wearables. We aim to thoroughly demonstrate each step in the design process for morphing arts and crafts projects triggered by various stimuli such as heat, moisture, and air pressure. Through open-source simulation tools, readily available materials, and easy-to-follow tutorials, morphing matter toolkits can empower users to express their creativity in new ways while learning science and engineering concepts, skills, and techniques.

We describe how sheets of metalized mylar can be cut and then “inflated” into complex 3D forms with electrostatic charge for use in digitally-controlled, shape-changing displays. This is achieved by placing and nesting various cuts, slits and holes such that mylar elements repel from one another to reach an equilibrium state. Importantly, our technique is compatible with industrial and hobbyist cutting processes, from die and laser cutting to handheld exacto-knives and scissors. Given that mylar film costs <$1 per m2, we can create self-actuating 3D objects for just a few cents, opening new uses in low-cost consumer goods. We describe a design vocabulary, interactive simulation tool, fabrication guide, and proof-of-concept electrostatic actuation hardware. We detail our technique’s performance metrics along with qualitative feedback from a design study. We present numerous examples generated using our pipeline to illustrate the rich creative potential of our method.

From transoceanic bridges to large-scale installations, truss structures have been known for their structural stability and shape complexity. In addition to the advantages of static trusses, truss structures have a large degree of freedom to change shape when equipped with rotatable joints and retractable beams. However, it is difficult to design a complex motion and build a control system for large numbers of trusses. In this paper, we present PneuMesh, a novel truss-based shape-changing system that is easy to design and build but still able to achieve a range of tasks. PneuMesh accomplishes this by introducing an air channel connection strategy and reconfigurable constraint design that drastically decreases the number of control units without losing the complexity of shape-changing. We develop a design tool with real-time simulation to assist users in designing the shape and motion of truss-based shape-changing robots and devices. A design session with seven participants demonstrates that PneuMesh empowers users to design and build truss structures with a wide range of shapes and various functional motions.

From creating input devices to rendering tangible information, the field of HCI is interested in using kinematic mechanisms to create human-computer interfaces. Yet, due to fabrication and design challenges, it is often difficult to create kinematic devices that are compact and have multiple reconfigurable motional degrees of freedom (DOFs) depending on the interaction scenarios. In this work, we combine compliant mechanisms (CMs) with tensioning cables to create dynamically reconfigurable kinematic mechanisms. The devices’ kinematics (DOFs) is enabled and determined by the layout of bendable rods. The additional cables function as on-demand motion constraints that can dynamically lock or unlock the mechanism's DOFs as they are tightened or loosened. We provide algorithms and a design tool prototype to help users design such kinematic devices. We also demonstrate various HCI use cases including a kinematic haptic display, a haptic proxy, and a multimodal input device.

Hydrogels are versatile morphing materials that have recently been adopted for creating shape-changing interfaces. However, most shape-changing interfaces require advanced material synthesis, specialized lab settings for fabrication, and technical knowledge is needed to simulate their morphing behavior. To replicate such structures, these factors become a barrier for makers. Therefore, to democratize the creation of hydrogel-based morphing artifacts and to extend their design space in HCI, we propose a water-triggered morphing mechanism that utilizes the distance between adjacent hydrogel beads adhered on a thin substrate to control their bending angle. This paper describes the bending angle quantification experiments for creating a simulator, the process of developing a computational tool along with its user-friendly workflow and demonstrates kirigami and branch-based artifacts built with the tool. Using our method, anyone can easily design and fabricate custom morphing structures.

Machine knitting is an increasingly accessible fabrication technology for producing custom soft goods. However, recent machine knitting research has focused on knit shaping, or on adapting hand-knitting patterns. We explore a capability unique to machine knitting: producing multilayer spacer fabrics. These fabrics consist of two face layers connected by a monofilament filler yarn which gives the structure stiffness and volume. We show how to vary knit patterning and yarn parameters in spacer fabrics to produce tactile materials with embedded functionality for forming soft actuated mechanisms and sensors with tunable density, stiffness, material bias, and bristle properties. These soft mechanisms can be rapidly produced on a computationally-controlled v-bed knitting machine and integrated directly into soft objects.

We present an inexpensive tabletop loom that offers fully computational patterning while maintaining the flexibility of handweaving. Our loom can be assembled for under US$200 with 3D printed parts, and it can be controlled straightforwardly over USB. Our loom is explicitly a hand loom: that is, a weaver is required to operate the weaving process and may mediate row-by-row patterning and material specifics like yarn tension. Our approach combines the flexibility of fully analog handweaving with the computational affordances of digital fabrication: it enables the incorporation of special techniques and materials, as well as allowing for the possibility of computational and creative interventions in the weaving process itself. In taking this approach, we aim to serve a range of end users including artisans and researchers, whether for skill-building, for rapid prototyping, or for creative reflection.

3D printing, as a rapid prototyping technique, usually fabricates objects that are difficult to modify physically. This paper presents FlexTruss, a design and construction pipeline based on the assembly of modularized truss-shaped objects fabricated with conventional 3D printers and assembled by threading. To create an end-to-end system, a parametric design tool with an optimal Euler path calculation method is developed, which can support both inverse and forward design workflow and multi-material construction of modular parts. In addition, the assembly of truss modules by threading is evaluated with a series of application cases to demonstrate the affordance of FlexTruss. We believe that FlexTruss extends the design space of 3D printing beyond typically hard and fixed forms, and it will provide new capabilities for designers and researchers to explore the use of such flexible truss structures in human-object interaction.

3D printing technology makes Do-It-Yourself and reforming everyday objects a reality. However, designing and fabricating attachments that can seamlessly adapt existing objects to extended functionality is a laborious process, which requires accurate measuring, modeling, manufacturing, and assembly. This paper presents ShrinCage, a 4D printing system that allows novices to easily create shrinkable adaptations to fit and fasten existing objects. Specifically, the design tool presented in this work aid in the design of attachment that adapts to irregular morphologies, which accommodates the variations in measurements and fabrication, subsequently simplifying the modeling and assembly processes. We further conduct mechanical tests and user studies to evaluate the availability and feasibility of this method. Numerous application examples created by ShrinCage prove that it can be adopted by aesthetic modification, assistive technology, repair, upcycling, and augmented 3D printing.

From providing nutrition to facilitating social exchanges, food plays an essential role in our daily lives and cultures. In HCI, we are interested in using food as an interaction medium and a context of personal fabrication. Yet, the design space of available food printing methods is limited to shapes with minimal overhangs and materials that have a paste-like consistency. In this work, we seek to expand this design space by adapting support bath-assisted printing to the food context. The bath scaffolds the embedded materials and preserves shapes during the printing processes, enabling us to create freeform food with fluid-like materials. We provide users guidelines for choosing the appropriate support bath type and processing methods depending on the printing material's properties. A design tool suite and application examples, including confectionery arts, 4D printed food, and edible displays are also offered to demonstrate the enabled interaction design space.

Computational handweaving combines the repeatable precision of digital fabrication with relatively high production demands of the user: a weaver must be physically engaged with the system to enact a pattern, line by line, into a fabric. Rather than approaching co-presence and repetitive labor as a negative aspect of design, we look to current practices in procedural generation (most commonly used in game design and screen-based new media art) to understand how designers can create room for suprise and emergent phenomena within systems of precision and constraint. We developed three designs for blending real-time input with predetermined pattern features. These include: using camera imagery sampled at weaving time; a 1:1 scale tool for composing patterns on the loom; and a live "Twitch'' stream where spectators determine the woven pattern. We discuss how experiential qualities of the systems led to different balances of underdetermination in procedural generation as well as how such an approach might help us think beyond an artifact/experience dichotomy in fabrication.

As sensors and interactive devices become ubiquitous and transition outdoors and into the wild, we are met with the challenge of mass deployment and actuation. We present E-seed, a biomimetic platform that consumes little power to deploy, harvests energy from nature to install, and functions autonomously in the field. Each seed can individually self-drill into a substrate by harvesting moisture fluctuations in its ambient environment. As such, E-seed acts as a shape-changing interface to autonomously embed functional devices and interfaces into the soil, with the potential of aerial deployment in hard-to-reach locations. Our system is constructed primarily from wood veneer, making it lightweight, inexpensive, and biodegradable. In this paper, we detail our fabrication process and showcase demos that leverage the E-seed platform as a self-drilling interface. We envision that possible applications include soil sensors, sampling, and environmental monitoring for agriculture and reforestation.

Morphing materials allow us to create new modalities of interaction and fabrication by leveraging the materials? dynamic behaviors. Yet, despite the ongoing rapid growth of computational tools within this realm, current developments are bottlenecked by the lack of an effective simulation method. As a result, existing design tools must trade-off between speed and accuracy to support a real-time interactive design scenario. In response, we introduce SimuLearn, a data-driven method that combines finite element analysis and machine learning to create real-time (0.61 seconds) and truthful (97% accuracy) morphing material simulators. We use mesh-like 4D printed structures to contextualize this method and prototype design tools to exemplify the design workflows and spaces enabled by a fast and accurate simulation method. Situating this work among existing literature, we believe SimuLearn is a timely addition to the HCI CAD toolbox that can enable the proliferation of morphing materials.

Four-dimensional (4D) printing, a new technology emerged from additive manufacturing (3D printing), is widely known for its capability of programming post-fabrication shape-changing into artifacts. Fused deposition modeling (FDM)-based 4D printing, in particular, uses thermoplastics to produce artifacts and requires computational analysis to assist the design processes of complex geometries. However, these artifacts are weak against structural loads, and the design quality can be limited by less accurate material models and numerical simulations. To address these issues, this paper propounds a composite structure design made of two materials – polylactic acid (PLA) and carbon fiber reinforced PLA (CFPLA) – to increase the structural strength of 4D printed artifacts and a workflow composed of several physical experiments and series of dynamic mechanical analysis (DMA) to characterize materials. We apply this workflow to 3D printed samples fabricated with different printed parameters to accurately characterize the materials and implement a sequential finite element analysis (FEA) to achieve accurate simulations. The accuracy of deformation induced by the triggering process is both computationally and experimentally verified with several creative design examples and is measured to be at least 95%, with a confidence interval of (0.972,0.985). We believe the presented workflow is essential to the combination of geometry, material mechanism and design, and has various potential applications.

With recent interest in shape-changing interfaces, material-driven design, wearable technologies, and soft robotics, digital fabrication of soft actuatable material is increasingly in demand. Much of this research focuses on elastomers or non-stretchy air bladders. Computationally-controlled machine knitting offers an alternative fabrication technology which can rapidly produce soft textile objects that have a very different character: breathable, lightweight, and pleasant to the touch. These machines are well established and optimized for the mass production of garments, but compared to other digital fabrication techniques such as CNC machining or 3D printing, they have received much less attention as general purpose fabrication devices. In this work, we explore new ways to employ machine knitting for the creation of actuated soft objects. We describe the basic operation of this type of machine, then show new techniques for knitting tendon-based actuation into objects. We explore a series of design strategies for integrating tendons with shaping and anisotropic texture design. Finally, we investigate different knit material properties, including considerations for motor control and sensing.

Despite thin-line actuators becoming widely adopted in different Human-Computer Interaction (HCI) contexts, including integration into fabrics, paper art, hinges, soft robotics, and human hair, accessible line-based actuators are very limited beyond shape memory alloy (SMA) wire and motor-driven passive tendons. In this paper, we introduce a novel, yet simple and accessible, line-based actuator. ModiFiber is a twisted-then-coiled nylon thread actuator with a silicone coating. This composite thread actuator exhibits unique two-way reversible shrinking or twisting behaviors triggered by heat or electrical current (i.e., Joule heating). ModiFiber is soft, flexible, safe to operate and easily woven or sewn, hence it has a great potential as an embedded line-based actuator for HCI purposes. In this paper, we explain the material mechanisms and manufacturing approaches, followed by some performance tests and application demonstrations.

Thermoplastic and Fused Deposition Modeling (FDM) based 4D printing are rapidly expanding to allow for space- and material-saving 2D printed sheets morphing into 3D shapes when heated. However, to our knowledge, all the known examples are either origami-based models with obvious folding hinges, or beam-based models with holes on the morphing surfaces. Morphing continuous double-curvature surfaces remains a challenge, both in terms of a tailored toolpath-planning strategy and a computational model that simulates it. Additionally, neither approach takes surface texture as a design parameter in its computational pipeline. To extend the design space of FDM-based 4D printing, in Geodesy, we focus on the morphing of continuous double-curvature surfaces or surface textures. We suggest a unique tool path - printing thermoplastics along 2D closed geodesic paths to form a surface with one raised continuous double-curvature tiles when exposed to heat. The design space is further extended to more complex geometries composed of a network of rising tiles (i.e., surface textures). Both design components and the computational pipeline are explained in the paper, followed by several printed geometric examples.

Wearables have emerged as an increasingly promising interactive platform, imbuing the human body with always-available computational capabilities. This unlocks a wide range of applications, including discreet information access, health monitoring, fitness, and fashion. However, unlike previous platforms, wearable electronics require structural conformity, must be comfortable for the wearer, and should be soft, elastic, and aesthetically appealing. We envision a future where electronics can be temporarily attached to the body (like bandages or party masks), but in functional and aesthetically pleasing ways. Towards this vision, we introduce ElectroDermis, a fabrication approach that simplifies the creation of highly-functional and stretchable wearable electronics that are conformal and fully untethered by discretizing rigid circuit boards into individual components. These individual components are wired together using stretchable electrical wiring and assembled on a spandex blend fabric, to provide high functionality in a robust form-factor that is reusable. We describe our system in detail- including our fabrication parameters and its operational limits-which we hope researchers and practitioners can leverage. We describe a series of example applications that illustrate the feasibility and utility of our system. Overall, we believe ElectroDermis offers a complementary approach to wearable electronics-one that places value on the notion of impermanence (i.e., unlike tattoos and implants), better conforming to the dynamic nature of the human body.

This paper presents A-line, a 4D printing system for designing and fabricating morphing three-dimensional shapes out of simple linear elements. In addition to the commonly known benefit of 4D printing to save printing time, printing materials, and packaging space, A-line also takes advantage of the unique properties of thin lines, including their suitability for compliant mechanisms and ability to travel through narrow spaces and self-deploy or self-lock on site. A-line integrates a method of bending angle control in up to eight directions for one printed line segment, using a single type of thermoplastic material. A software platform to support the design, simulation and tool path generation is developed to support the design and manufacturing of various A-line structures. Finally, the design space of A-line is explored through four application areas, including line sculpting, compliant mechanisms, self-deploying, and self-locking structures.

Living things in nature have long been utilizing the ability to "heal" their wounds on the soft bodies to survive in the outer environment. In order to impart this self-healing property to our daily life interface, we propose Self-healing UI, a soft-bodied interface that can intrinsically self-heal damages without external stimuli or glue. The key material to achieving Self-healing UI is MWCNTs-PBS, a composite material of a self-healing polymer polyborosiloxane (PBS) and a filler material multi-walled carbon nanotubes (MWCNTs), which retains mechanical and electrical self-healability. We developed a hybrid model that combines PBS, MWCNTs-PBS, and other common soft materials including fabric and silicone to build interface devices with self-healing, sensing, and actuation capability. These devices were implemented by layer-by-layer stacking fabrication without glue or any post-processing, by leveraging the materials' inherent self-healing property between two layers. We then demonstrated sensing primitives and interactive applications that extend the design space of shape-changing interfaces with their ability to transform, conform, reconfigure, heal, and fuse, which we believe can enrich the toolbox of human-computer interaction (HCI).

In this paper, we explore personalized morphing food that enhances traditional food with new HCI capabilities, rather than replacing the chef and authentic ingredients (e.g. flour) with an autonomous machine and heterogeneous mixtures (e.g. gel). Thus, we contribute a unique transformation mechanism of kneaded and sheeted flour-based dough, with an integrated design strategy for morphing food during two general cooking methods: dehydration (e.g. baking) or hydration (e.g. water boiling). We also enrich the design space of morphing food by demonstrating several applications. We end by discussing hybrid cooking between human and a design tool that we developed to ensure accuracy while preserving customizability for morphing food.

We develop a novel method printing complex self-folding geometries. We demonstrated that with a desktop fused deposition modeling (FDM) 3D printer, off-the-shelf printing filaments and a design editor, we can print flat thermoplastic composites and trigger them to self-fold into 3D with arbitrary bending angles. This is a suitable technique, called Thermorph, to prototype hollow and foldable 3D shapes without losing key features. We describe a new curved folding origami design algorithm, compiling given arbitrary 3D models to 2D unfolded models in G-Code for FDM printers. To demonstrate the Thermorph platform, we designed and printed complex self-folding geometries (up to 70 faces), including 15 self-curved geometric primitives and 4 self-curved applications, such as chairs, the simplified Stanford Bunny and flowers. Compared to the standard 3D printing, our method saves up to 60% - 87% of the printing time for all shapes chosen.

We present PEP (Printed Electronic Papercrafts), a set of design and fabrication techniques to integrate electronic based interactivities into printed papercrafts via 3D sculpting. We explore the design space of PEP, integrating four functions into 3D paper products: actuation, sensing, display, and communication, leveraging the expressive and technical opportunities enabled by paper-like functional layers with a stack of paper. We outline a seven-step workflow, introduce a design tool we developed as an add-on to an existing CAD environment, and demonstrate example applications that combine the electronic enabled functionality, the capability of 3D sculpting, and the unique creative affordances by the materiality of paper.

We present a printed paper actuator as a low cost, reversible and electrical actuation and sensing method. This is a novel but easily accessible enabling technology that expands upon the library of actuation-sensing materials in HCI. By integrating three physical phenomena, including the bilayer bending actuation, the shape memory effect of the thermoplastic and the current-driven joule heating via conductive printing filament, we developed the actuator by simply printing a single layer conductive Polylactide (PLA) on a piece of copy paper via a desktop fused deposition modeling (FDM) 3D printer. This paper describes the fabrication process, the material mechanism, and the transformation primitives, followed by the electronic sensing and control methods. A software tool that assists the design, simulation and printing toolpath generation is introduced. Finally, we explored applications under four contexts: robotics, interactive art, entertainment and home environment.

We present 4DMesh, a method of combining shrinking and bending thermoplastic actuators with customized geometric algorithms to 4D print and morph centimeter- to meter-sized functional non-developable surfaces. We will share two end-to-end inverse design algorithms. With our tools, users can input CAD models of target surfaces and produce respective printable files. The flat sheet printed can morph into target surfaces when triggered by heat. This system saves shipping and packaging costs, in addition to enabling customizability for the design of relatively large non-developable structures. We designed a few functional artifacts to leverage the advantage of non-developable surfaces for their unique functionalities in aesthetics, mechanical strength, geometric ergonomics and other functionalities. In addition, we demonstrated how this technique can potentially be adapted to customize molds for industrial parts (e.g., car, boat, etc.) in the future.

We developed a concept of transformative appetite, where edible 2D films made of common food materials (protein, cellulose or starch) can transform into 3D food during cooking. This transformation process is triggered by water adsorption, and it is strongly compatible with the 'flat packaging' concept for substantially reducing shipping costs and storage space. To develop these transformable foods, we performed material-based design, established a hybrid fabrication strategy, and conducted performance simulation. Users can customize food shape transformations through a pre-defined simulation platform, and then fabricate these designed patterns using additive manufacturing. Three application techniques are provided - 2D-to-3D folding, hydration-induced wrapping, and temperature-induced self-fragmentation, to present the shape, texture, and interaction with food materials. Based on this concept, several dishes were created in the kitchen, to demonstrate the futuristic dining experience through materials-based interaction design.

To meet the increasing requirements of HCI researchers who are looking into using liquid-based materials (e.g., hydrogels) to create novel interfaces, we present a design strategy for HCI researchers to build and customize a liquid-based smart material printing platform with off-the-shelf or easy-to-machine parts. For the hardware, we suggest a magnetic assembly-based modular design. These modularized parts can be easily and precisely reconfigured with off-the-shelf or easy-to-machine parts that can meet different processing requirements such as mechanical mixing, chemical reaction, light activation, and solution vaporization. In addition, xPrint supports an open-source, highly customizable software design and simulation platform, which is applicable for simulating and facilitating smart material constructions. Furthermore, compared to inkjet or pneumatic syringe-based printing systems, xPrint has a large range of printable materials from synthesized polymers to natural micro-organism-living cells with a printing resolution from 10μm up to 5mm (droplet size). In this paper, we will introduce the system design in detail and three use cases to demonstrate the material variability and the customizability for users with different demands (e.g., designers, scientific researchers, or artists).

Nature has engineered its own actuators, as well as the efficient material composition, geometry and structure to utilize its actuators and achieve functional transformation. Based on the natural phenomenon of cells' hygromorphic transformation, we introduce the living Bacillus Subtilis natto cell as a humidity sensitive nanoactuator. In this paper, we unfold the process of exploring and comparing cell types that are proper for HCI use, the development of the composite biofilm, the development of the responsive structures, the control setup for actuating biofilms, and a simulation and fabrication platform. Finally, we provide a variety of application designs, with and without computer control to demonstrate the potential of our bio actuators. Through this paper, we intend to enable the use of natto cells and our platform technologies for HCI researchers, designers and bio-hackers. More generally, we try to encourage the research and use of biological responsive materials and interdisciplinary research in HCI.

We propose soft planar actuators enhanced by free-form fabrication that are suitable for making everyday objects move. The actuator consists of one or more inflatable pouches with an adhesive back. We have developed a machine for the fabrication of free-from pouches; squares, circles and ribbons are all possible. The deformation of the pouches can provide linear, rotational, and more complicated motion corresponding to the pouch's geometry. We also provide a both manual and programmable control system. In a user study, we organized a hands-on workshop of actuated origami for children. The results show that the combination of the actuator and classic materials can enhance rapid prototyping of animated objects.

This paper presents a weight-changing device based on the transfer of mass. We chose liquid metal (Ga-In-Tin eutectic) and a bi-directional pump to control the mass that is injected into or removed from a target object. The liquid metal has a density of 6.44g/cm3, which is about six times heavier than water, and is thus suitable for effective mass transfer. We also combine the device with a dynamic volume-changing function to achieve programmable mass and volume at the same time. We explore three potential applications enabled by weight-changing devices: density simulation of different materials, miniature representation of planets with scaled size and mass, and motion control by changing gravity force. This technique opens up a new design space in human-computer interactions.

This works introduces layer jamming as an enabling technology for designing deformable, stiffness-tunable, thin sheet interfaces. Interfaces that exhibit tunable stiffness properties can yield dynamic haptic feedback and shape deformation capabilities. In comparison to the particle jamming, layer jamming allows for constructing thin and lightweight form factors of an interface. We propose five layer structure designs and an approach which composites multiple materials to control the deformability of the interfaces. We also present methods to embed different types of sensing and pneumatic actuation layers on the layer-jamming unit. Through three application prototypes we demonstrate the benefits of using layer jamming in interface design. Finally, we provide a survey of materials that have proven successful for layer jamming.

This paper presents PneUI, an enabling technology to build shape-changing interfaces through pneumatically-actuated soft composite materials. The composite materials integrate the capabilities of both input sensing and active shape output. This is enabled by the composites' multi-layer structures with different mechanical or electrical properties. The shape changing states are computationally controllable through pneumatics and pre-defined structure. We explore the design space of PneUI through four applications: height changing tangible phicons, a shape changing mobile, a transformable tablet case and a shape shifting lamp.

The proliferation of broadband and high-speed Internet access has, in general, democratized the ability to commonly engage in videoconference. However, current video systems do not meet their full potential, as they are restricted to a simple display of unintelligent 2D pixels. In this paper we present a system for enhancing distance-based communication by augmenting the traditional video conferencing system with additional attributes beyond two-dimensional video. We explore how expanding a system's understanding of spatially calibrated depth and audio alongside a live video stream can generate semantically rich three-dimensional pixels containing information regarding their material properties and location. We discuss specific scenarios that explore features such as synthetic refocusing, gesture activated privacy, and spatiotemporal graphic augmentation.

Piying is an old Chinese art form and one of the origins of the modern movie. In Piying, the shadow of fur made characters with delicate carving could be seen by audience in front of the curtain. The artists behind the curtain control the actions of shadows using sticks fastened to the characters.

The hearing handicapped children show a penchant for dancing and dance plays an essential part in education of deaf children. This paper introduces the Music-touch Shoes, a pair of shoes particularly designed for hearing handicapped dancers: The rhythm and tempo of music can be communicated and perceived through the vibrotactile interaction. The vibrotactile interface is applied to shoes because feet are among the body parts which are most directly involved in performing dancing rhythm. The different sequences, intensity and frequency of vibrations reflect different rhythm and tempo of music. This project sought to explore a way of making up for the shortage of hearing ability through interaction with other senses, such as vibrotactile sense, to fulfill the same dancing entertainment demand of the hearing handicapped people.