Theoretical analysis of resonant lateral electrostatic Comb drive actuator and sensor

Abstract

This paper investigates the electrostatic drive, sense, spring behavior of long beams, resonant frequency, quality factor, resonator noise and damping of resonator parallel to the substrate, using an interdigitated capacitor (electrostatic comb). Resonant frequency of the device is 9.5 kHz with quality factor 104. Couette damping is dominant that is equal to 5.34×10^•8. The value of Squeeze film damping is small i.e. 2.436×10^•13 due to end faces of the fingers of comb resonator. Dominant noise is Brownian and spectral density of this noise force due to Couette and Squeeze film damping are 8.843×10^•28 and 4.035×10^•33 N²/Hz respectively. At damping ratio 0.0048 electrostatic force of 29.5 nN produces 11.4µm amplitude at resonance in the sensing fingers which shows capacitive sensitivity equals to 0.3684 fF/µm.