An Oil-Filled MEMS Resonant Pressure Sensor Based on Electrostatic Stiffness Modulation

This letter presents an oil-filled micro-electro mechanical system (MEMS) resonant pressure sensor based on electrostatic stiffness modulations to mitigate the side effects of oil expansion during temperature changes. In this device, tunable bias voltages were employed to adjust the nonmonotonic property of the resonators for pressure sensing to maintain high performances within wide temperature range of −55° to 125°C. Microfabrication was conducted to manufacture the sensor chip. Compared with the sensor without electrostatic stiffness modulation, the developed sensor demonstrated a high pressure fitting accuracy of ±0.02%FS (full scale). Further tests revealed high performances of the developed device within full pressure (10kPa to 200kPa) and temperature ranges, including pressure accuracy of ±0.02% FS, repeatability of 0.01% FS, pressure hysteresis of 0.01% FS, nonlinearity of 0.01% FS, and temperature hysteresis of 0.02% FS. The method can also be suitable for non-oil-filled resonant pressure sensor to extend the working temperature range.