A Resonant Accelerometer Based on Piezoelectric TBTF MEMS Resonator and Two-stage Microleverage

In this paper, a resonant accelerometer based on piezoelectric triple-beam tuning fork (TBTF) MEMS resonator is presented, which is implemented in the form of an oscillator. Compared with the conventional resonant accelerometer based on capacitive resonators, the presented resonant accelerometer adopts piezoelectric TBTF resonator as the core sensing unit, which has advantages such as large electromechanical transduction capability, no requirement for high DC voltage bias and vacuum package. The designed TBTF resonator uses out-of-plane vibration mode and thus improves the axial force sensitivity compared to traditional double-ended tuning fork (DETF) device operating in in-plane vibration mode. Also, the piezoelectric transduction of TBTF is generally larger than that of DETF, which benefits attaining higher signal-to-noise ratio at the sensor output. Moreover, a two-stage micro-leverage is herein utilized for force transfer, which amplifies the axial acceleration force by nearly two orders of magnitude, further enhancing the sensitivity of the device. In this work, the frequency response of the TBTF resonator was measured, based on which the equivalent circuit parameters were extracted for design of the oscillator. The reported resonant accelerometer exhibit measured acceleration sensitivity of 18 Hz/g and resolution of 0.293 g at atmospheric pressure.