Comparative study of printed capacitive sensors

This paper presents a comparative study of four planar capacitive sensors with different geometrical layouts. These sensors have been fabricated by inkjet printing on a flexible substrate whose electrical permittivity is dependent on relative humidity. We have used numerical simulations to design each of these structures. In particular, we present the calibration curves of interdigitated electrodes, meandered electrodes, spiral electrodes, and serpentine electrodes in terms of relative humidity. Although the selection of the best configuration will depend on the specific application and its requirements, in terms of sensitivity within the same sensing area the lowest value is achieved by meandered electrodes, followed by interdigitated, spiral, and serpentine electrodes, in this order.