Piezoelectric Composite Transducers for Ultrasonic Diagnostic Applications

The acoustic impedance of the piezoelectric composites over the frequency range of 0.5-7.5h4hz was measured using the reflection , the echo shift and the resonant techniques. There was a significant difference between the impedance measured by the reflection technique in comparision with the other two techniques. Within each technique, the impedance was found to be a function of the volume percentage of the ceramic and not a function of frequency. Focused transducers were made using grinding and thermal forming processes. The pulse echo response of the composite transducers seems to be similar to ceramic transducers.