Study of a high sensitivity transverse comb-drive as small force sensor

Abstract

A MEMS based capacitive sensor for high sensitivity micro-force measurement is proposed and discussed. A 3D-model is considered for only one equivalent capacitance, which resulted outputs can be extracted to the entire device, when multiplied by the number of the combs. The effects of various semiconductors as the base material are studied and the output results are compared. The ratio of the calculated differential capacitance to the value of applied force is suggested as the device sensitivity. It is resulted that Gallium Arsenide has faster response and higher resolution in an equal bias voltage range. The suggested comb-drive sensor could be used to measure the input applied force lower than 0.32 milli-Newton, with the sensitivity higher than 3.14 fF/mN. The device sensitivity can be enhanced again with increasing the number of combs.