An efficient method for modeling planar interdigitated electrodes for capacitive sensing

Interdigitated electrodes represent a commonly used planar structure when it comes to implementing capacitive sensors. The calculation of the created electric fields, however, is very complicated as soon as cover layers are involved. We present a simple semi-analytical approach, which yields approximate expressions for the capacitance between the electrodes. The method can be easily adapted to geometries with multiple cover layers. As an example, the sensitivity of the capacitance to changes in the permittivity for alternate wiring schemes of electrodes is discussed.