Capacitive touch keypads consists of one or more capacitive buttons. The capacitive touch buttons/sensors can be printed on a polyester film using conductive ink, or can be copper pads on a PCB. These sensors are connected to the IC. When a button is pressed, the IC measures the increase in capacitance and triggers a response.
The main advantage of capacitive touch keypads are that there are no mechanical moving parts, which will eventually wear out. These capacitive sensors are placed underneath any non-conductive overlay material such as AR-1 Acrylic, thick polyester and hardcoated polycarbonate, and ABS Plastic, making them virtually indestructible. This construction is also very easy to clean, which makes it a good choice for medical applications.