Bio-based and bio-degradable materials have shown promising results for sustainable Human-Computer Interaction (HCI) applications, including shape-changing interfaces. However, the diversity of shape-changing behaviors achievable with these materials remains unclear as the fabrication knowledge is scattered across multiple research fields. This paper introduces SoftBioMorph, a fabrication framework that aims to integrate the fabrication know-how of sustainable soft shape-changing interfaces with biopolymers. Based on the example of Sodium Alginate, the framework contributes (1) a set of material synthesis processes that modify the biopolymer’s properties to fulfill different functions; (2) a set of DIY crafting-based assembling techniques that functionalize the material and assembling properties to achieve three primitive types of change in shape; and (3) a series of application cases that demonstrate the versatility of the framework. We further discuss limitations, research questions, and fabrication challenges, presenting a comprehensive approach to sustainable prototyping in HCI.

Haptic exoskeleton gloves are a widespread solution for providing force-feedback in Virtual Reality (VR), especially for 3D object manipulations. However, they are still lacking an important feature regarding in-hand haptic sensations: the palmar contact. In this paper, we present PalmEx, a novel approach which incorporates palmar force-feedback into exoskeleton gloves to improve the overall grasping sensations and manual haptic interactions in VR. PalmEx's concept is demonstrated through a self-contained hardware system augmenting a hand exoskeleton with an encountered palmar contact interface - physically encountering the users' palm. We build upon current taxonomies to elicit PalmEx's capabilities for both the exploration and manipulation of virtual objects. We first conduct a technical evaluation optimising the delay between the virtual interactions and their physical counterparts. We then empirically evaluate PalmEx's proposed design space in a user study (n=12) to assess the potential of a palmar contact for augmenting an exoskeleton. Results show that PalmEx offers the best rendering capabilities to perform believable grasps in VR. PalmEx highlights the importance of the palmar stimulation, and provides a low-cost solution to augment existing high-end consumer hand exoskeletons.

Additive manufacturing of silicone is increasingly being explored to complement the traditional molding fabrication technique for Soft Pneumatic Actuators (SPAs). However, the mechanical behavior of SPAs is defined by their 3D form, which leads to prioritizing the SPAs mechanical properties over their aspect. In this paper, we propose a novel SPA fabrication method where the mechanical properties of a silicone part are defined during the fabrication phase rather than the 3D modeling phase, leading to the object's mechanical properties being independent of the object's aspect. This novel SPA fabrication method, named Local Layer Splitting (LLS), consists of local modifications of the printing layer height to integrate stiffness variation, thus generating controlled mechanical deformation when pressured. We discovered that silicone printing layer height impacts the final stiffness of the material, and it could be used to program bending deformation to actuators during printing. We first characterize the effect of the layer height parameters on 3D-printed silicone stiffness with tensile tests. Then, we present a custom slicer we developed to generate G-codes with local layer height variations depending on the x and y positions. We then characterize the bending and force achievable by SPAs made with the LLS process and find that they match those of state-of-the-art SPAs. Finally, we present and discuss how the LLS method impacts the SPAs design by shifting the bending behavior integration from the SPAs 3D conception to their fabrication phase.

Living bio-materials are increasingly used in HCI for fabricating objects by growing. However, how to integrate electronics to make these objects interactive still needs to be clarified. This paper presents an exploration of the fabrication design space of Biohybrid Interactive Devices, a class of interactive devices fabricated by merging electronic components and living organisms. From the exploration of this space using bacterial cellulose, we outline a fabrication framework centered on the biomaterials‘ life cycle phases. We introduce a set of novel fabrication techniques for embedding conductive elements, sensors, and output components through biological (e.g. bio-fabrication and bio-assembling) and digital processes. We demonstrate the combinatory aspect of the framework by realizing three tangible, wearable, and shape-changing interfaces. Finally, we discuss the sustainability of our approach, its limitations, and the implications for bio-hybrid systems in HCI.

Designers and makers are increasingly interested in leveraging bio-based and bio-degradable ‘do-it-yourself’ (DIY) materials for sustainable prototyping. Their self-produced bioplastics possess compelling properties such as self-adhesion but have so far not been functionalized to create soft interactive devices, due to a lack of DIY techniques for the fabrication of functional electronic circuits and sensors. In this paper, we contribute a DIY approach for creating Interactive Bioplastics that is accessible to a wide audience, making use of easy-to-obtain bio-based raw materials and familiar tools. We present three types of conductive bioplastic materials and their formulation: sheets, pastes and foams. Our materials enable additive and subtractive fabrication of soft circuits and sensors. Furthermore, we demonstrate how these materials can substitute conventional prototyping materials, be combined with off-the-shelf electronics, and be fed into a sustainable material ‘life-cycle’ including disassembly, re-use, and re-melting of materials. A formal characterization of our conductors highlights that they are even on-par with commercially available carbon-based conductive pastes.

Humans have the ability to convey an array of emotions through complex and rich touch gestures. However, it is not clear how these touch gestures can be reproduced through interactive systems and devices in a remote mediated communication context. In this article, we explore the design space of device-initiated touch for conveying emotions with an interactive system reproducing a collection of human touch characteristics. For this purpose, we control a robotic arm to touch the forearm of participants with different force, velocity and amplitude characteristics to simulate human touch. In view of adding touch as an emotional modality in human-machine interaction, we have conducted two studies. After designing the touch device, we explore touch in a context-free setup and then in a controlled context defined by textual scenarios and emotional facial expressions of a virtual agent. Our results suggest that certain combinations of touch characteristics are associated with the perception of different degrees of valence and of arousal. Moreover, in the case of non-congruent mixed signals (touch, facial expression, textual scenario) not conveying a priori the same emotion, the message conveyed by touch seems to prevail over the ones displayed by the visual and textual signals.

We are surrounded by sensing devices. We are accustomed to them, appreciate their benefits, and even create affective bonds and might neglect the implications they might have for our daily life. By presenting Eyecam, an anthropomorphic webcam mimicking a human eye, we challenge conventional relationships with ubiquitous sensing devices and call to re-think how sensing devices might appear and behave. Inspired by critical design, Eyecam is an exaggeration of a familiar sensing device which allows for critical reflections on its perceived functionalities and its impact on human-human and human-device relations. We identify 5 different roles Eyecam can take: Mediator, Observer, Mirror, Presence, and Agent. Contributing design fictions and thinking prompts, we allow for articulation on privacy awareness and intrusion, affect in mediated communication, agency and self-perception along with speculation on potential futures. We envision this work to contribute to a bold and responsible design of ubiquitous sensing devices.

Physical Human-Robot-Interaction (pHRI) is beneficial for communication in social interaction or to perform collaborative tasks but is also crucial for safety. While robotic devices embed sensors for this sole purpose, their design often is the results of a trade-off between technical capabilities and rarely considers human factors. We propose a novel approach to design and fabricate compliant Human-like artificial skin sensors for robots, with similar mechanical properties as human skin and capable of precisely detecting touch. Our artificial skin relies on the use of different silicone elastomers to replicate the human skin layers and comprises an embedded electrode matrix to perform mutual capacitance sensing. We present the sensor and describe its fabrication process which is scalable, low-cost and ensures flexibility, compliance and robustness. We introduce Muca, an open-source sensing development board and then evaluate the performance of the sensor.

We present a method for enabling arbitrary textiles to sense pressure and deformation: In-situ polymerization supports integration of piezoresistive properties at the material level, preserving a textile's haptic and mechanical characteristics. We demonstrate how to enhance a wide set of fabrics and yarns using only readily available tools. To further support customisation by the designer, we present methods for patterning, as needed to create circuits and sensors, and demonstrate how to combine areas of different conductance in one material. Technical evaluation results demonstrate the performance of sensors created using our method is comparable to off-the-shelf piezoresistive textiles. As application examples, we demonstrate rapid manufacturing of on-body interfaces, tie-dyed motion-capture clothing, and zippers that act as potentiometers.

We propose a paradigm called Skin-On interfaces, in which interactive devices have their own (artificial) skin, thus enabling new forms of input gestures for end-users (e.g. twist, scratch). Our work explores the design space of Skin-On interfaces by following a bio-driven approach: (1) From a sensory point of view, we study how to reproduce the look and feel of the human skin through three user studies;(2) From a gestural point of view, we explore how gestures naturally performed on skin can be transposed to Skin-On interfaces; (3) From a technical point of view, we explore and discuss different ways of fabricating interfaces that mimic human skin sensitivity and can recognize the gestures observed in the previous study; (4) We assemble the insights of our three exploratory facets to implement a series of Skin-On interfaces and we also contribute by providing a toolkit that enables easy reproduction and fabrication.

In this paper, we explore the interaction space of MobiLimb, a small 5-DOF serial robotic manipulator attached to a mobile device. It (1) overcomes some limitations of mobile devices (static, passive, motionless); (2) preserves their form factor and I/O capabilities; (3) can be easily attached to or removed from the device; (4) offers additional I/O capabilities such as physical deformation and (5) can support various modular elements such as sensors, lights or shells. We illustrate its potential through three classes of applications: As a tool, MobiLimb offers tangible affordances and an expressive controller that can be manipulated to control virtual and physical objects. As a partner, it reacts expressively to users' actions to foster curiosity and engagement or assist users. As a medium, it provides rich haptic feedback such as strokes, pat and other tactile stimuli on the hand or the wrist to convey emotions during mediated multimodal communications.