A Triaxial Accelerometer Based on Differential Resonant Beams and Force-Balanced Capacitive plates

This paper presents the design, simulation, fabrication, and experiment of a triaxial accelerometer based on differential resonant beams and force-balanced capacitive plates. The triaxial accelerometer is composed of a proof mass, four bridge resonators with both end clamped and operating in flexure vibration mode, four L-type supporting beams, and a top plate and a bottom plate. The in-plane acceleration is measured by bridge resonators. The gravity center of the proof mass and the neutral layer of L-type supporting beams are located within the same plane to minimize the rotation of the proof mass subjected to in-plane acceleration. The cross-axis sensitivities of X-axis and Y-axis resonant beams under lateral in-plane acceleration are 1.97% and 1.71%, respectively. A force-balanced differential plate capacitor composed of a proof mass, a top plate, and a bottom plate is used to detect acceleration along Z-axis. The small displacement of the proof mass in the normal direction of the chip reduces the cross-axis sensitivity of the bridge resonators subjected to acceleration along Z-axis. The complementation of the resonance detection mechanism and the force balance capacitance mode makes the triaxial accelerometer exhibit low cross-axis sensitivity. The simulated and experimental results prove this conclusion.