Patent ID: 8487624

Claim:
A fingerprint sensor for measuring surface structures, the fingerprint sensor comprising: a chosen number of sensor elements at chosen positions for coupling to a surface having a size less or comparable to a size of the surface structures; a processing unit comprising interrogation electrodes coupled to said sensor elements for providing impedance measurements at said surface structures, the processing unit being mounted on one side of a substrate and the sensor elements being positioned on an opposite side of said substrate; the substrate comprising: through going first conducting leads between said sensor elements and said interrogation electrodes; wherein the substrate is made from a semiconductor material; wherein said first conducting leads are constituted by through going substrate sections of a chosen size surrounded by an insulating material; wherein the first conducting leads are made from identical material as the substrate; and wherein the substrate comprises at least one second conductor lead, the at least one second conductor lead being constituted by a section of the substrate being insulated from the substrate with a dielectric material; and an external electrode being coupled to a finger surface and to said processing unit through said at least one second conductor lead, the external electrode being substantially larger that the surface structures.