Single Key Qtouch Capacitive Touch Sensor in SOT-23-6 Package, 1.8V, 5.5V - 

Digital burst mode, charge-transfer sensor capable of detecting near-proximity or touch. It features a 'max on' setting which allows the key to re-calibrate to detect subsequent touches when faced with an obstruction for a prolonged period of time. The sensor projects a touch or proximity field to several centimetres through any dielectric including glass, plastic, stone, ceramic, and even most kinds of wood. It can turn small metal-bearing objects into intrinsic sensors, making them responsive to proximity or touch. It is designed specifically for human interfaces and includes all hardware and signal processing functions necessary to provide stable sensing under a wide variety of changing conditions. Only a single low-cost capacitor is required for operation.