The invention relates to a smart card (47) comprising: the card body having a recess formed therein； and a sensor unit (21) mounted in the recess and configured to detect features of a surface of an object (10) contacting the sensor unit, the sensor unit comprising: a contact surface (9) exposed at an external surface of the sensor unit； a first dielectric layer (39) constituting said contact surface and covering a second dielectric layer (40) and having a first surface and a second surface opposite the first surface； a plurality of electrodes (1,2,3) mounted on or embedded in the first surface of the second dielectric layer (40)； a plurality of conductive paths (4,5,6), at least one conductive path of the plurality of conductive paths extending from each of the electrodes (1,2,3) and at least partially through the second dielectric layer (40)； a circuit board having a first surface (41) and a second surface (42) opposite the first surface, wherein the second dielectric layer (40) is mounted directly or indirectly on the first surface of the circuit board； and at least one processor (13) mounted on the second surface of the circuit board, wherein the circuit board is configured to provide an electrical connection between the conductive paths (4,5,6) and the at least one processor (13), wherein the at least one processor is configured to detect a voltage or current at the electrodes via the conductive paths (4,5,6).
