Please see the picture which shows the basic working principle: When body, as the earth capacitance, touches the electrode, capacitance CF will be formed between the induction electrode with the earth. The induction capacitance usually ranges from several pF to tens of pF. Making use of this basic principle, related circuit outside is established, and IC can detect if body touches electrode by the changing of capacitance.

Comparing with traditional mechanical keys, capacitive touch sensor is not only slinky but also with long life time and durable. It subverts traditional keypad control. Only with slight touch, It can realize the control of switches, quantizing, and even direction.
Currently our group can achieve the design for below products: