Capacitive sensing technology is based on the detection of the capacitive effect of the human finger. Whenever there is an electrode and a finger is put on or close to it, capacitance is being added. Thus, the controller detects a capacitance change, and, depending on the settings of its registers, it identifies whether it is a touch or not. It is a very simple implementation as far as the sensor goes, because it is only a copper pad, and it can have different shapes, as can be seen on this slide.