PZT/Polymer composites for medical ultrasonic probes

Abstract

PZT/polymer composite sheets (PZT pillars embedded in polymer matrix) for high frequency use are fabricated using a dicing and filling technique. These piezo-composite sheets are intended for use as medical ultrasonic probes. It is found that dielectric and electromechanical properties depend not only on the PZT volume fraction v _PZT but also on the PZT pillar shape w/t (width-to-thickness ratio). Thickness dilatational electromechanical coupling factor k _t is as high as 0.75 when v _PZT = 0.25 and w/t = 0.5 ∼ 0.6. The period of the embedded PZT pillar lattice, d, is also important in determining the electromechanical properties. When d is close to the wavelength of laterally propagating transverse waves, lateral mode resonances are observed.