Pressure and Temperature Sensitivity of a Dual-Mode Quartz Pressure Sensor for High Pressure Applications

Dual-mode quartz-based pressure sensor (AXQG) for extreme pressures and temperatures has been recently commercialized. It consists of a thickness-shear SBTC-cut quartz resonator sandwiched between two quartz end-caps. The pressure and temperature (P-T) sensing element is a disc resonator that can be excited into two thickness-shear resonances through the application of an external electric field. The slow thickness-shear (C-) mode is temperature compensated at 25 degC, and is used for pressure sensing, whereas the fast thickness-shear (B-) mode is stress compensated and is used for temperature sensing of the resonator disc and this helps to compensate the temperature effects on the C-mode. The dual-mode resonator characteristics enable to have a pressure sensor with superior accuracy and fast dynamic compensation in the presence of temperature gradients. To achieve superior meteorological performance with a high manufacturing yield it is important to investigate the behavior of these fundamental thickness-shear modes and their anharmonic modes at high temperature and high pressure. In this paper, we developed a 3D FEA model by implementing the incremental stress equations in Lagrangian formulation to calculate the effect of pressure and temperature on the sensitivities of different modes of interest for the AXQG pressure sensor. The 3D FEA model shows an excellent agreement with the measured data for the AXQG subjected to extreme pressure and temperature conditions.