Get You an E-Textiles Sensor That Can Do Both

[Admar] is a software developer who was introduced to e-textiles in 2011. The bug firmly took hold, and these days he gives e-textile workshops at Eindhoven University of Technology. Here, students learn to build a single e-textile sensor that detects both presence and pressure. The workshop presentations are available on his site, which is itself a window into his e-textile journey.

Over the years, [Admar] has discovered that any e-textile project requiring more than a few connections is ripe for some kind of textile-friendly multi-point connector. Through trial and error, he designed a robust solution for use with an embroidery machine. The wires are made from conductive thread and soldered to a row of male header pins to make the transition out of fiber space. This transition requires solder, which quickly gets interesting when coupled with a fabric substrate and no solder mask. We wonder if spraying on mask beforehand would help, or if it would just soak in and stain and get in the way.

You can see the connector in practice in [Admar]’s capacitive multi-touch demo video after the break. He has stacked two pieces of fabric, each with a wire bus made of conductive threads, with the traces at right angles. Both sensors are wired to a Cypress PSoC5 to create a sensor matrix, and then to a laptop for visualization purposes. As his fingers approaches the fabric, the bar graphs roar upward to show increased capacitance. Once he makes contact, each finger appears as a yellow dot illustrating pressure.

E-textile projects aren’t limited to traces sewn by hand or embroidery machine. Circuit boards can be knitted, too.