A Micromachined Resonant Micro-Pressure Sensor

This article presents a micromachined resonant micro-pressure sensor, which consists of a SOI wafer for pressure sensing and a glass cap for vacuum packaging. More specifically, two resonators fabricated in device layer of SOI wafer were positioned around the center and border of pressure-sensitive diaphragm respectively with the purposed of transforming pressure. Simulations based on finite element analysis were applied to the design and optimization of the micro-pressure sensor where technical issues correlated with mechanical coupling and overloading were addressed properly. The micro-pressure sensors were fabricated by silicon based bulk-micromachining processes, and characterized by both open-loop and closed-loop testing. The characterization results revealed quality factors higher than 25000 in full pressure (0.05 kPa to 10 kPa) and temperature (-40°C to 85°C) scales, and at least 12 times of anti-overload capabilities for developed sensors. The differential pressure sensitivities were quantified as 615.47±9.82 Hz/kPa (-40°C), 589.56±4.34 Hz/kPa (15°C) and 561.70 ±8.75 Hz/kPa (85°C) respectively, as well the repeatability, hysteresis, and nonlinearity were calculated as 0.0485±0.0032%, 0.0299±0.0018%, and 0.0493±0.0025% respectively for the developed sensors. Meanwhile, the maximum fitting deviations were quantified within ±5.24 Pa in full pressure (0.05 kPa to 10 kPa) and temperature (-40°C to 85°C) scales, demonstrating accuracies of 0.0524% full scale, further indicating that the developed sensor is a potential candidate in the field of micro-pressure measurements.