Ultrasonic Probe Using Composite Piezoelectric Materials

High frequency (5 and 7.5MHz) ultrasonic probes using a PZT/polymer 1-3 composite were developed and ultrasonic images were obtained with them. Many kinds of 1-3 composites can be made by the "dicing and filling" technique. Properties of the composite are determined as a function of materials, PZT volume fraction, and PZT pillar size and shape. The electromechanical coupling factor is high and the acoustic impedance is low under optimum conditions. There is a possibility that the probe using the composite may have a grating lobe, but it can be suppressed by using a fine pitch composite. Taking these factors into consideration, a 7.5MHz concave single probe and a SMHz convex array were fabricated, and good acoustic images were obtained with them. These acoustic images were as good as those obtained by using a conventional probe.