A high sensitivity quartz resonant pressure sensor with differential output and self-correction.

Abstract

A high sensitivity quartz resonant pressure sensor with differential output and self-correction is proposed. Although compared to other resonant devices, quartz resonators have less influence on external environmental factors due to their own high quality factor Q; the influence of external environment such as temperature, vibration, and humidity cannot be ignored in high-precision applications. These errors need to be eliminated or compensated. Therefore, this paper divides the core unit of the sensor into two parts: the working unit and the reference unit. The working unit provides the differential outputs which not only improves the sensitivity but also suppresses some interference such as time drift and temperature drift, and it is rarely used in quartz resonant pressure sensors. The reference unit can effectively detect and offset the interference of temperature and vibration which is named as self-correction, and it can also provide temperature measurement. Double-ended tuning fork quartz resonators used in both units are manufactured by micromachining technology. Bellows and flexible mechanisms used as pressure conversion units are manufactured using modern mechanical technology. The test results show that the sensor has the conformity accuracy of the fitting formula of 0.0148% full scale (FS), the good basic accuracy of 0.06% FS, and the high sensitivity of 36.58 Hz/kPa which meets well with the theoretical result. It is shown by the experiments that the reference unit can effectively correct the interference of temperature and vibration. The theoretical analysis and experimental results prove the feasibility of the resonant pressure sensor which can meet the application requirements of pressure measurement in the high-tech industries.