High-precision BESOI-based resonant accelerometer

A uniaxial resonant acceleration sensor for high-precision measurements, made in bulk micromachining, is presented. The high symmetry of the device structure eliminates rotational acceleration components and diminishes cross-axis sensitivities. Silicon direct bonding, and the use of commercial BESOI (bond and etch back silicon on insulator) wafers, form the sensor structure, which is a silicon-silicon sandwich. The vibrating element is a silicon beam that is driven electrothermally and sensed piezoresistively. Closed-loop operation of the resonator by means of an electronic feedback circuit is demonstrated. Also in closed-loop operation, static and dynamic measurements of prototypes have been performed, showing the very good mechanical properties of the device. The method employed for dynamic testing of a resonant accelerometer on a vibrating table is described.