Living body detection method and apparatus (touching behavior)

A method of detecting possible living body contact at an electrical conductive surface, wherein the living body has a contact portion having electrical properties resembling an impedance bridge comprising a plurality of resistors and a plurality of capacitors connected in series and parallel and having a characteristic rise-time and a characteristic fall-time, wherein the impedance bridge comprises a resistor series (R0+R1+R2) having a total resistance value and a resistor-capacitor first RC bridge comprising a parallel connection of a first resistor (R1) having a first resistance value and a first capacitor (C1) having a first capacitance value, and the resistor series (R0+R1+R2) comprises an internal resistor (R0) in series connection with the first RC bridge and having an internal resistance value;

• and wherein the method comprises:
• sending a pulse train of voltage pulses to the contact surface, wherein the pulse train comprises a plurality of voltage pulses as probing pulses and each voltage pulse has a sharp edge which changes from a first voltage level which is a base voltage level to a second voltage level, and a flat region at the second voltage level;
• detecting current responses from the contact surface to the pulse train;
• and
• determining whether there is possible living body contact at the electrical conductive surface with reference to the current responses.