<p>The invention relates to a sensor for measuring structures in a surface, e.g. a fingerprint sensor comprising a chosen number of sensor elements at chosen positions for coupling to a finger surface having a size less or comparable to the size of the structures in the finger surface, and a processing unit including interrogation electrodes coupled to said sensor elements for providing impedance measurements at said finger surface, the processing unit being mounted on one side of a substrate and the sensor elements being positioned on the opposite side of said substrate, the substrate including through going first conducting leads between said sensor elements and said interrogation electrodes. The substrate is made from a semiconductor material such as silicon and said first conducting leads are constituted by through going substrate sections of a chosen size surrounded byan insulating dielectric separating them from the substrate.</p>
