Injection molded fine-scale piezoelectric composite transducers

A ceramic injection molding process has been developed for net-shape forming complex-shaped PZT 1-3 and 2-2 element arrays that are suitable for direct assembly into composite transducers. The process offers a low cost, shape-versatile alternative to the conventional dice-and-fill method of composite transducer fabrication now widely used in the medical ultrasound industry. This technique has been used to produce 1-3 composite preforms having 19×19 arrays of 1.15 mm diameter PZT rods. When assembled into a larger array, the 1-3 composite transducers outperform PVDF and 0-3 composites in both sensing and projection operation. The limits of the process are being explored in an attempt to achieve smaller PZT element dimensions suitable for high frequency ultrasonic imaging. With appropriate tooling, the process is capable of producing arrays of extremely fine elements: 1-3 composites having <100 μm diameter PZT fibers and 2-2 composites with 25 μm wide PZT strips have been demonstrated