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. We imagine aluminum foil ...

The Touch Board is based around an Arduino Leonardo board that also sports an MP3 player / MIDI device, a MicroSD card socket, 3.5 mm audio jack and what Johnson described as the "secret sauce ...

Instead of using mechanical paddles, [Sebastian] brought his iambic key into the 21st century by using a touch sensor. An ATtiny45 measures the time it takes for a single metal plate to fully charge.