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 ...

Researchers from University of British Columbia in Vancouver have created a flexible sensor using conductive gel and silicon. The stretchy sensor is sensitive to different types of touch.