Double-ended tuning fork resonant strain sensor operated in atmospheric environment using a galvanic protection technique

This paper presents a double-ended tuning fork (DETF) resonant strain sensor that is designed to operate in an atmospheric environment. The design is based on the fact that the driving amplitude at resonance increases with the increase of the gap width when the squeeze film damping dominates. An equivalent circuit model is developed. The main cause of feed-through has been revealed by the model and the experiments, and a symmetrical design is employed to suppress it. The sensor is fabricated using Au/Si galvanic protection. A very high yield has been achieved. The strain sensor presents a sensitivity of 39 Hz/με and a quality factor of 1574 in an atmospheric environment.