Development of High-Sensitivity Ultrasonic Transducer in Air with Nanofoam Material

For a high-sensitivity ultrasonic transducer in air, it was considered that nanofoam be applied to its acoustic matching layer. Nanofoam is a porous material that is made by the sol-gel process. Since nanofoam has an extremely low acoustic impedance, it is effective for the acoustic matching layer of an ultrasonic transducer in air. In this study, we have fabricated an ultrasonic transducer that had two acoustic matching layers and estimated its acoustic properties. The two matching layers were made of silica nanofoam and porous ceramic. The sensitivity of the developed ultrasonic transducer was about twenty times higher than that of a conventional ultrasonic transducer in air.