Ultrasound barrier based on packaged micromachined membrane resonators

We report on a prototype of a miniaturized, short range ultrasound barrier for contactless object detection. Micromachined membrane resonators with electrothermal excitation and piezoresistive detection of vibrations act as transducer elements. The devices are fabricated with an industrial silicon process on (100) wafers compatible to bipolar IC technology. The 1 mm by 1 mm membrane resonators have been optimized with respect to their sound generation efficiency. Moreover, we investigate packaging techniques in order to protect the transducer elements without obstructing the ultrasound path.