P1M-8 Acoustic Properties of Nanofoam and its Applied Air-Borne Ultrasonic Transducers

Nanofoam is a porous material called drying gel or aerogel. Nanofoam has a low density and a low acoustic velocity. Because of these properties, it was considered that nanofoam can realize high performance air-borne ultrasonic transducer. We applied nanofoam to two types of ultrasonic transducers. One is a matching layer type of ultrasonic transducer (ML-UT), and the other is refractive propagation type of ultrasonic transducer (RP-UT). The sensitivity of ML-UT was twenty times as high as conventional. And we confirmed the basic operation of RP-UT on the basis of the observation of the propagation of ultrasonic in the peculiar direction and broadband characteristics. The frequency bandwidth of RP-UT was more than three times as wide as conventional