Hybrid MEMS-IDT based accelerometer and gyroscope in a single chip

摘要

In this paper, recent advances made on wireless MEMS-IDT (Interdigital Transducer) based accelerometers and gyroscopes at Penn State and HVS are presented. The concept and design principles are based on using surface acoustic waves (SAW) and polysilicon seismic mass for acceleration and proof mass for gyro. By designing the seismic mass of the accelerometer to float just above a high frequency Rayleigh Surface Acoustic Wave Sensor (SAWS), we are able to realize the accuracy and versatility required for the measurement of accelerations from 10~(-6) g to l00g. The gyro design is based on the combination of Surface Acoustic Wave Resonator (SAWR) and Surface Acoustic Wave Sensor, which operates at the Rayleigh mode. The transmitter IDT creates SAW that propagates back and forth between the reflectors and forms a standing wave pattern within the cavity space between the IDTs. The particles at the anti-nodes of standing wave pattern experience large amplitude of vibration perpendicular to the plane of the substrate, which serves as the reference vibrating motion for the gyroscope. A number of metallic (proof) masses are strategically positioned at the anti-node locations so that the effect of the Coriolis force can be used to sense the gyroscopic motion.