Use of Composite Materials for a B-Scan Transducer

Several types of piezoceramic/polymer composites with 1-3 connectivity are being studied as new ultrasonic biomedical transducers. Their underwater acoustic behavior has been studied at one to five MHz and these data are compared to the thickness mode figure of merit and other properties of composites. One composite disc 41-mm diameter by 1-mm thick was flexible enough to form a concaved spherical cap with a 7.5 cm radius. This transducer had a maxium response at 1.5 MHz and was naturally matched at resonance to the 5 0 ohm impedance of the power supply. The one-half amplitude bandwidth was 1.3 MHz but the time domain signal exhibited some minor energy before and after the main pulse. A new very high sensitivity composite material was also identified for future B-scan transducers.