Patent ID: 7856262

Claim:
Method for inspecting whether an object consists of living skin, the method comprising the following steps: measuring electrical characteristics of two outer layers of skin, wherein said two outer layers of skin comprise respectively a stratum corneum and living skin, comparing the measured electrical characteristics with corresponding, known characteristics of skin of a living or a dead finger, wherein the measurements of electrical characteristics in the two skin layers is characterized in applying an alternating current or voltage with at least one frequency to the skin between two current supply electrodes, measuring a complex voltage as a function of frequency between one of said current supply electrodes and a first electrode positioned at a chosen distance from said one current supply electrode for said at least one frequency, measuring a complex voltage between the first electrode and a second electrode, wherein the second electrode is positioned at a larger distance from said one first current supply electrode than said first electrode for said at least one frequency, calculating immittance for the two skin layers based on said voltage measurements, and using said immittance as a basis for comparing with corresponding, known characteristics of skin of a live or a dead finger.