The sensor forms an image and OpenCV detects the actual touch configuration. It appears you can use the raw data from the Arduino, too, but it might be a little harder.

This tutorial will guide you through the process of building a tachometer around an Arduino. Tachometers are used to measure rotation rate in Revolutions Per Minute (RPM). You don’t need much… ...

Touch Board works with any conductive material, and although it comes pre-programmed, it can also be programmed like any other Arduino.