Integrated tactile imager with an intrinsic contour detection option

Abstract This paper presents a 9 row by 9 column capacitive tactile imaging sensor. As it can act like a differential operator, it is intrinsically suitable for edge detection. The sensor consists of a conductive rubber layer placed on top of an isolating rubber layer, which is in turn attached to a silicon wafer. The 28 × 28 mm integrated circuit is covered by 81 square-shaped aluminium electrodes and also contains the addressing logic and the signal-conditioning circuits. Each electrode establishes a tactile element (taxel). The operation involves the capacitive measurement of the indentation pattern of the non-conductive natural rubber layer, caused by the pressure distribution acting on the sensor surface, when scanning the taxels. The local deformation of the isolating rubber between a selected square and the common conductive rubber electrode causes a change in the capacitance as low as 1 fF, which can be detected using a specially designed driving method and phase read-out.