Design and test of a micromachined resonant accelerometer with high scale factor and low noise

This paper describes the design, fabrication and experimental evaluation of a silicon micromachined resonant accelerometer that demonstrates high sensitivity and low noise. The device is fabricated with the silicon-on-glass micromachining technology and vacuum packaged to permit the double-ended-tuning-fork resonators operated at extremely high quality factor, up to 3.5 × 105. Structure optimization of the one-stage micro-lever, resonator and bearing beam is discussed to produce a high scale factor of 221.67 Hz/g, which is confirmed by the measured value of 244.15 Hz/g at a full scale range of ±15 g. Various frequency noise sources are modeled and discussed to explain the acceleration measurement noise associated with the vibration amplitude of the resonator and further optimize the drive voltage. By setting an optimized drive voltage at 10 mV, the measured noise and resolution of the MRA prototype are 0.38 μg/Hz and 0.63 μg, respectively. Compared to other reported MRAs, this accelerometer benefits from the optimization of the device geometry dimensions and the applied drive voltage, which exhibits both high scale factor and low noise.