TTP224 4-channel Capacitive touch sensor Module uses the touch-sensing IC TTP224 to sense the touch input. The module has 4 touch pads. Power the module with 2.4 ~ 5.5V DC and the touch pad is all active to sense the input. Four Channel Capacitive Touch Module is easy to interface. It can be used along with a microcontroller or an Arduino or even without one. When a capacitive load is in close proximity to the sense-pad, the sensor detects the change in capacitance and activates the switch. Custom sense-pads can be made from nearly any conductive material and these sensors can detect touch through thin layers of non-conductive materials such as glass, plastic, fabric or even wood.