Integrating sensors into knitted input devices traditionally comes with considerable constraints for textile and UI design freedom. In this work, we demonstrate a novel, minimally invasive method for fabricating knitted sensors that overcomes this limitation. We integrate copper wire with piezoresistive enamel directly into the fabric using weft knitting to establish strain and pressure sensing cells that consist only of single pairs of intermeshed loops. The result is unobtrusive and potentially invisible, which provides tremendous latitude for visual and haptic design. Furthermore, we present several variations of stitch compositions, resulting in loop meshes that feature distinct response with respect to direction of exerting force. Utilizing this property, we are able to infer actuation modalities and considerably expand the device’s input space. In particular, we discern strain directions and surface pressure. Moreover, we provide an in-depth description of our fabrication method, and demonstrate our solution’s versatility on three exemplary use cases.

With spaceR, we present both design and implementation of a resistive force-sensor based on a spacer fabric knit. Due to its softness and elasticity, our sensor provides an appealing haptic experience. It enables continuous input with high precision due to its innate haptic feedback and can be manufactured ready-made on a regular two-bed weft knitting machine, without requiring further post-processing steps. For our multi-component knit, we add resistive yarn to the filler material, in order to achieve a highly sensitive and responsive pressure sensing textile. Sensor resistance drops by ~90% when actuated with moderate finger pressure of 2 N, making the sensor accessible also for straightforward readout electronics. We discuss related manufacturing parameters and their effect on shape and electrical characteristics and explore design opportunities to harness visual and tactile affordances. Finally, we demonstrate several application scenarios by implementing diverse spaceR variations, including analog rocker- and four-way directional buttons, and show the possibility of mode-switching by tracking temporal data.

In this paper, we present TexYZ, a method for rapid and effortless manufacturing of textile mutual capacitive sensors using a commodity embroidery machine. We use enameled wire as a bobbin thread to yield textile capacitors with high quality and consistency. As a consequence, we are able to leverage the precision and expressiveness of projected mutual capacitance for textile electronics, even when size is limited. Harnessing the assets of machine embroidery, we implement and analyze five distinct electrode patterns, examine the resulting electrical features with respect to geometrical attributes, and demonstrate the feasibility of two promising candidates for small-scale matrix layouts. The resulting sensor patches are further evaluated in terms of capacitance homogeneity, signal-to-noise ratio, sensing range, and washability. Finally, we demonstrate two use case scenarios, primarily focusing on continuous input with up to three degrees-of-freedom.

We present a novel method for augmenting arbitrary fabrics with textile-based pressure sensors using an off-the-shelf embroidery machine. We apply resistive textiles and conductive yarns on top of a base fabric, to yield a flexible and versatile continuous sensing device, which is based on the widespread principle of force sensitive resistors. The patches can easily be attached to measurement and/or computing devices, e.g. for controlling accessories. In this paper, we investigate the impacts of related design and fabrication parameters, introduce five different pattern designs, and discuss their pros and cons. We present crucial insights and recommendations for design and manufacturing of embroidered pressure sensors. Our sensors show a very low activation threshold, as well as good dynamic range, signal-to-noise ratio, and part-to-part repeatability.

We present Sonoflex, a thin-form, embroidered dynamic speaker made without using a permanent magnet. Our design consists of two flat spiral coils, stacked on top of each other, and is based on an isolated, thin (0.15 mm) enameled copper wire. Our approach allows for thin, lightweight, and textile speakers and does not require high voltage as in electrostatic speakers. We show how the speaker can be designed and fabricated and evaluate its acoustic properties as a function of manufacturing parameters (size, turn counts, turn spacing, and substrate materials). The experiment results revealed that we can produce audible sound with a broad frequency range (1.5 kHz - 20 kHz) with the embroidered speaker with a diameter of 50 mm. We conclude the paper by presenting several applications such as audible notifications and near-ultrasound communication.