High Frequency Thin-Film Piezoelectric Resonant Micro-Accelerometers with A Capacitive Mass-Spring Transducer

A novel resonant micro-accelerometer is implemented with an operational frequency of ~27 MHz in which an acceleration-induced change of capacitance is transformed to a frequency shift in a piezoelectric resonator utilizing the piezoelectric stiffening mechanism. In this device the mass-spring system is not embedded within the resonator, enabling a large degree of freedom in choosing the resonance frequency of the resonator. The piezoelectric resonator and the capacitive mass spring (CMS) structure are both fabricated on a silicon-on-insulator (SOI) wafer covered by a thin film of sputtered aluminum nitride. The feasibility and the efficiency of this novel sensing mechanism has been proven by demonstrating a ~600 Hz shift in the resonance frequency as the sample accelerometer was rotated 1800 yielding a 300Hz.g-1 sensitivity.