Versatile air-coupled phased array transducer for sensor applications

Abstract

We introduce a versatile one-dimensional (1D) air-coupled phased array transducer device operating at 40 kHz. It allows both -transmit beam steered ultrasound at high sound pressure level and it can sense beam steered ultrasound. This device opens the door to many new sensory applications. Conventionally, low frequency sensor array design for air-coupled application was not possible due to the inter element spacing (also referred as pitch) criteria that needs to be satisfied for given applications. We overcome this limitation by introducing a smart packaging layer that separates the acoustic aperture from the actual radiating aperture of the ultrasonic transducer. By doing this, we ensure that the half wavelength criteria is fulfilled. The proposed new design leads to a wide operation range without any undesirable grating lobes. A proof of concept prototype device was built and its performance evaluated in the laboratory. An impressive 130 ± 1 dB sound pressure level (SPL) was observed at a distance of 1 m. The prototype also was capable of steering approximately 110 • in total, in both transmit and receive mode of operation.