Resolution improvement in electromagnetically actuated Wheatstone bridge configuration micromechanical resonators

Abstract In this paper we present the novel approach to design of a resonating sensor fabricated as a micro-electromechanical system (MEMS) made of the silicon nitride double clamped beam (microbridge) and the thin film metal paths enabling both actuation and read-out. We propose the on-chip implemented Wheatstone bridge circuit as a mean for increasing the actuation efficiency and readout sensitivity. Two of the bridge branches are actuating and sensing Lorentz loops while other two are reference resistors on immobile, supported structure. Such approach allowed to increase the response fourfold compared to single Lorentz loop. It was possible to observe the resonance in vacuum and in ambient conditions. The necessary power dissipation to actuate measurable vibrations were 130 pW and 13 nW, respectively.