Machine embroidery is a versatile technique for creating custom and entirely fabric-based patterns on thin and conformable textile surfaces. However, existing machine-embroidered surfaces remain static, limiting the interactions they can support. We introduce Embrogami, an approach for fabricating textile structures with versatile shape-changing behaviors. Inspired by origami, we leverage machine embroidery to form finger-tip-scale mountain-and-valley structures on textiles with customized shapes, bistable or elastic behaviors, and modular composition. The structures can be actuated by the user or the system to modify the local textile surface topology, creating interactive elements like toggles and sliders or textile shape displays with an ultra-thin, flexible, and integrated form factor. We provide a dedicated software tool and report results of technical experiments to allow users to flexibly design, fabricate, and deploy customized Embrogami structures. With four application cases, we showcase Embrogami’s potential to create functional and flexible shape-changing textiles with diverse visuo-tactile feedback.

Mutual-capacitive sensing is the most common technology for detecting multi-touch, especially on flat and simple curvature surfaces. Its extension to a more complex shape is still challenging, as a uniform distribution of sensing electrodes is required for consistent touch sensitivity across the surface. To overcome this problem, we propose a method to adapt the sensor layout of common capacitive multi-touch sensors to more complex 3D surfaces, ensuring high-resolution, robust multi-touch detection. The method automatically computes a grid of transmitter and receiver electrodes with as regular distribution as possible over a general 3D shape. It starts with the computation of a proxy geometry by quad meshing used to place the electrodes through the dual-edge graph. It then arranges electrodes on the surface to minimize the number of touch controllers required for capacitive sensing and the number of input/output pins to connect the electrodes with the controllers. We reach these objectives using a new simplification and clustering algorithm for a regular quad-patch layout. The reduced patch layout is used to optimize the routing of all the structures (surface grooves and internal pipes) needed to host all electrodes on the surface and inside the object's volume, considering the geometric constraints of the 3D shape. Finally, we print the 3D object prototype ready to be equipped with the electrodes. We analyze the performance of the proposed quad layout simplification and clustering algorithm using different quad meshing and characterize the signal quality and accuracy of the capacitive touch sensor for different non-planar geometries. The tested prototypes show precise and robust multi-touch detection with good Signal-to-Noise Ratio and spatial accuracy of about 1mm.

Personal fabrication has mostly focused on handheld tools as embodied extensions of the user, and machines like laser cutters and 3D printers automating parts of the process without intervention. Although interactive digital fabrication has been explored as a middle ground, existing systems have a fixed allocation of user intervention vs. machine autonomy, limiting flexibility, creativity, and improvisation. We explore a new class of devices that combine the desirable properties of a handheld tool and an autonomous fabrication robot, offering a continuum from manual and assisted to autonomous fabrication, with seamless mode transitions. We exemplify the concept of mixed-initiative physical sketching with a working robotic printer that can be handheld for free-hand sketching, can provide interactive assistance during sketching, or move about for computer-generated sketches. We present interaction techniques to seamlessly transition between modes, and sketching techniques benefitting from these transitions to, e.g., extend (upscale, repeat) or revisit (refine, color) sketches. Our evaluation with seven sketchers illustrates that RoboSketch successfully leverages each mode’s strengths, and that mixed-initiative physical sketching makes computer-supported sketching more flexible.

When vibrations are synchronized with our actions, we experience them as material properties. This has been used to create virtual experiences like friction, counter-force, compliance, or torsion. Implementing such experiences is non-trivial, requiring high temporal resolution in sensing, high fidelity tactile output, and low latency. To make this style of haptic feedback more accessible to non-domain experts, we present Haptic Servos: self-contained haptic rendering devices which encapsulate all timing-critical elements. We characterize Haptic Servos’ real-time performance, showing the system latency is <5 ms. We explore the subjective experiences they can evoke, highlighting that qualitatively distinct experiences can be created based on input mapping, even if stimulation parameters and algorithm remain unchanged. A workshop demonstrated that users new to Haptic Servos require approximately ten minutes to set up a basic haptic rendering system. Haptic Servos are open source, we invite others to copy and modify our design.

We present Print-A-Sketch, an open-source handheld printer prototype for sketching circuits and sensors. Print-A-Sketch combines desirable properties from free-hand sketching and functional electronic printing. Manual human control of large strokes is augmented with computer control of fine detail. Shared control of Print-A-Sketch supports sketching interactive interfaces on everyday objects – including many objects with materials or sizes which otherwise are difficult to print on. We present an overview of challenges involved in such a system and show how these can be addressed using context-aware, dynamic printing. Continuous sensing ensures quality prints by adjusting inking-rate to hand movement and material properties. Continuous sensing also enables the print to adapt to previously printed traces to support incremental and iterative sketching. Results show good conductivity on many materials and high spatial precision, supporting on-the-fly creation of functional interfaces.

In traditional body-art, designs are adjusted to the body as they are applied, enabling creative improvisation and exploration. Conventional design and fabrication methods of epidermal interfaces, however, separate these steps. With BodyStylus we present the first computer-assisted approach for on-body design and fabrication of epidermal interfaces. Inspired by traditional techniques, we propose a hand-held tool that augments freehand inking with digital support: projected in-situ guidance assists creating valid on-body circuits and aesthetic ornaments that align with the human bodyscape, while pro-active switching between inking and non-inking creates error preventing constraints. We contribute BodyStylus’s design rationale and interaction concept along with an interactive prototype that uses self-sintering conductive ink. Results of two focus group explorations showed that guidance was more appreciated by artists, while constraints appeared more useful to engineers, and that working on the body inspired critical reflection on the relationship between bodyscape, interaction, and designs.

We present polymerized sports tape as a general purpose prototyping and sensor-design resource. We use it in a somewhat similar manner to how conductive copper tape is often used for fast production of lo-fi electrical prototypes. However, copper tape has a number of drawbacks if one is prototyping with soft materials, textiles, or even directly on the human body. Because it is not elastic, it does not adhere well to such materials. Sports tape, however, has the desired elastic qualities, and additionally is designed to adhere not only to arbitrary objects, but also to human skin. We polymerize sports tape to make it conductive. The resulting conductive tape has a series of electrical properties which make it an exciting sensor-material. It is piezo-resistive. This means its resistance changes with applied forces. It can also be used to create a voltage gradient, which enables simple and precise position sensing. This unique combination of mechanical and electrical properties makes it an exciting and unique prototyping resource.

Mutual capacitance-based multi-touch sensing is now a ubiquitous and high-fidelity input technology. However, due to the complexity of electrical and signal processing requirements, it remains very challenging to create interface prototypes with custom-designed multi-touch input surfaces. In this paper, we introduce Multi-Touch Kit, a technique enabling electronics novices to rapidly prototype customized capacitive multi-touch sensors. In contrast to existing techniques, it works with a commodity microcontroller and open-source software and does not require any specialized hardware. Evaluation results show that our approach enables multi-touch sensors with a high spatial and temporal resolution and can accurately detect multiple simultaneous touches. A set of application examples demonstrates the versatile uses of our approach for sensors of different scales, curvature, and materials.

Skin-based touch input opens up new opportunities for direct, subtle, and expressive interaction. However, existing skin-worn sensors are restricted to single-touch input and limited by a low resolution. We present the first skin overlay that can capture high-resolution multi-touch input. Our main contributions are: 1) Based on an exploration of functional materials, we present a fabrication approach for printing thin and flexible multi-touch sensors for on-skin interactions. 2) We present the first non-rectangular multi-touch sensor overlay for use on skin and introduce a design tool that generates such sensors in custom shapes and sizes. 3) To validate the feasibility and versatility of our approach, we present four application examples and empirical results from two technical evaluations. They confirm that the sensor achieves a high signal-to-noise ratio on the body under various grounding conditions and has a high spatial accuracy even when subjected to strong deformations.