A laterally driven micromachined resonant pressure sensor

A new type of resonant pressure sensor is presented which employs a laterally driven resonant strain gauge. The resonant strain gauge is designed using simple linear elastic theory and the sensor fabricated by a combination of bulk- and surface-micromachining techniques. The strain gauge is driven electrostatically and the resultant vibration sensed capacitively. Its lateral mode of oscillation offers several advantages, such as a Q-factor insensitive to the leakage of cavity gases. The resonator has been designed to have a fundamental frequency of 52 kHz and a gauge factor of 60 Hz mu N-1. Preliminary measurements of devices yield a fundamental frequency of 52+/-15 kHz, a Q-factor in air of 50 and a pressure sensitivity of 8.8 kHz bar(-1).