Digital Capacitive Touch Switch Module is based on TTP223B. Normally,it outputs low and keeps at low power state. When a touch is sensed on the circular marked region, it outputs high and switch to the quick response state. When not being touched for 12 seconds, it switches to low power state again. If the module is mounted in the surfaces of non-metallic materials such as plastic, glass, acrylic, you can make the keys hidden in the walls and desks.