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.

You can’t have a touch sensitive switch without a way to detect the presence of a finger! A touch sensor, especially a capacitive touch sensor, has some surprisingly sophisticated electronics to ...

Inside the TouchYou is an Arduino Pro Mini connected to a Bluetooth module. This Arduino communicates with force sensors and touch sensors and also has an output for a small vibration motor.