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.

To take full advantage of the Touch Board's capacitive capabilities, a bit of "distance code" can be uploaded to the board, making the touch sensor sensitive enough that you can interact with it ...

The e-Health Sensor Platform was designed by Cooking Hacks to help researchers and developers measure biometric sensor data for experimentation, fun and test purposes.