Quartz resonant micro-structures as sensing elements for temperature sensors

This paper describes the development of a temperature sensor based on a bulk acoustic waves micro-resonator vibrating in thickness shear mode. Two different cuts are chosen taking into account the thermal sensitivity, the electromechanical coupling factor, the trapped energy conditions. Care is also taken of technical problems caused by anisotropic chemical etching fabrication process. The active element of the structure is a circular thin plate suspended by four bridges micromachined in a NH₄F.HF solution. The performances of resonators are tested in the range 20-100 C. Experimental results on Q factor and thermal sensitivity for our suspended resonators appear to be encouraging when compared with experimental values obtained with a bridgeless resonator and with theoretical results