Characterization of the sensitivity of piezoelectric resonant pressure/force sensor with a new automatic device

摘要

A fully automated novel apparatus for the characterization of the sensitivity of piezoelectric resonant pressure/force sensor is proposed. The force-frequency effect of piezoelectric resonant sensors is the correlation between the force applied on the crystal resonator and the relative response resonant frequency shift of the resonator to the applied force. The force-frequency effect is closely related to the sensitivity of the pressure/force sensors. The new apparatus has been designed and fabricated to automatically measure the force-frequency relation at different azimuth angles Psi and force sensitivity coefficient K-f m.s/N which relates to parameters such as crystal geometry (diameter, thickness), orientation angle, and force direction (azimuth angle Psi). PI control is utilized for the automated measurement of force-frequency relation in crystal resonator. In addition, a lead screw mechanism is designed to yield precise linear motion of the clamp and minimize the backlash of the moving parts. As a result, the apparatus can automatically apply force on the crystal, measure the corresponding output frequency shift and yield the force-frequency relation graph. It also has a better force resolution and is simpler to adjust for force alignment. Moreover, the measurement time is reduced and the measurement result is more accurate. In order to validate this novel automated loading device, experiment tests on samples have been performed, and a comparison of the experiment outcomes with peers' measurement results shows a good agreement.