Micromachined acoustic Fabry-Perot system for distance measurement

We report on a packaged miniaturized ultrasound based distance measurement system. The measurement principle is based on acoustic resonances between object and sensor, similar to the Fabry-Perot principle known in optics. The sensor system consists of two micromachined membrane resonators acting as ultrasound transmitter and receiver. The proximity sensor can measure distances in air in the range of 1 to 10 cm with an accuracy better than 0.8 mm.