Miniaturization of a wide range load sensor using AT-cut quartz crystal resonator

A compact load sensor we developed uses an AT-cut quartz crystal resonator whose resonance frequency changes under external load, and features high sensitivity, high-speed response, and a wide measurement range. Also it has the superior feature in the temperature and frequency stability. In the past, the quartz crystal resonator had been hardly applied to the load measurement because of low degree of mechanical characteristic, that is, it is weak to stress concentration by bending. We have developed and characterized a sensor mechanism that safely maintains the quartz crystal resonator. The sensor had enormously wide range of 10⁴ N. The objective of this study is to miniaturize the sensor and to improve the resolution of load measurement. We designed a novel retention mechanism of the quartz crystal resonator which had frictionless structure. We calculated and analyzed about the new retention mechanism, and determined parameters. The size of the retention mechanism was 7.0 mm wide, 4.0 mm deep and 1.9 mm high, which was 40.3% of the conventional one (volume ratio).