Patent ID: 7496216

Claim:
A method of capturing, with a conductive fingerprint sensor having a return/supply contact and a plurality of contact pads, an image representative of skin, wherein the skin has ridges and valleys, the method comprising: placing the return/supply contact and one or more of the plurality of contact pads in electrical contact with the skin; measuring an electrical parameter of the skin in electrical contact with the return/supply contact and one or more of the contact pads; and storing data as a function of electrical contact of the skin ridges to the contact pads, wherein the measuring and storing data includes applying a direct current voltage source to the skin; measuring the electrical parameter of skin in electrical contact with the return/supply contact and one or more of the contact pads in response to applying the direct current voltage source; determining whether the measurements resulting from applying the direct current voltage source are unsatisfactory; applying an alternating current voltage source to the skin if the measurements resulting from applying the direct current voltage source are unsatisfactory; and correlating both the direct current and alternating current measurements.