zPatch: Hybrid Resistive/Capacitive eTextile Input

We love the idea of interactive clothing. Clothing that uses textiles to sense what the wearer is doing, or sense explicit input. The problem with such textiles is that it is easy to trigger them unintentionally (is the user pushing on the sleeve, or is the user just stuffing their jacket into their backpack?).

Different types of sensors measure different things, for example with resistive sensors we can measure pressure input, while capacitive measure allows measuring limited proximity and approach behaviors as well as touch.

If we combine these, can we create sensor that are a) more robust and b) support basic gesture recognition, while being worn?

Yes, we can create something like that. We did, and we call it zPatch

Watch how we make them and what they can do in the video below:

The way this works is that we take advantage of the multi-purpose nature of the pins of an Arduino. The zPatch connects to two Analog Inputs of the Arduino, lets say A0 and A1. In this case we first configure A0 as input, connected to an internal pullup resistor. We then configure A1 as output and set it LOW. Then we measure the zPatches resistance using analogRead(). Subsequently we reconfigure the pins, to measure their capacitance (we learned how to do this by digging in Martin2250's ADCTouch Library: https://playground.arduino.cc/Code/ADCTouch).

See the raw sensor output here:

All our code is open source. More detailed documentation can be found at https://zpatch.github.io/ and in our paper. Step-by step instructions on instructables.com