Within the scope of our TextileUX research endeavor, we developed a method to embroider pressure sensors on-top of arbitrary existing textiles.
Our sensors are made of 100% textile components and work just like common FSR (Force-Sensing Resistor) sensors, which enable to measure the amount of applied pressure or stress in a continuous manner. FSRs are widespread for decades, e.g. in touch screens not requiring skin-touch. They are primitive and durable elements, commonly made of conductive polymer ink, screen print onto two plastic foils, which are then sandwiched to form two electrodes.
In contrast, our sensors are based on a textile material, which is a weave of carbon-based monofilaments (also knits are possible), sandwiched in between two layers of electrically conductive yarn, which form the electrodes. In terms of operation, they show very low activation threshold, good dynamic range and signal-to-noise ratio. Consequently, they are straightforward to use in combination with basic measurement electronics, just as print FSRs. For data readout, preprocessing, and communication with remote devices (smartphones, watches, PCs…), we developed a custom PCB, which can be attached directly onto the augmented fabric. We connect the sensors also by embroidering the required circuit paths.
Using an off-the-shelf embroidery machine, our sensors can be manufactured rapidly, in a huge variety of patterns and sizes, and may have arbitrary outlines, providing great latitude also for design and visual appeal. Furthermore, we can link or combine a high number of sensors for building more complex pressure sensitive configurations, with high flexibility for sensing resolution and spatial arrangement. Moreover, our sensors preserve the respective qualities inherent to textiles, e.g. they are flexible, breathable, unobtrusive, and comfortable to wear and touch.