Novel piezocomposites for ultrasonic transducer applications

In ultrasonic medical imaging it is desirable to have a focused beam with maximum sensitivity along the transmission axis. One way to suppress the intensity of side lobes which impairs the image quality, is to introduce a ceramic volume fraction gradient (VFG) in piezoelectric composite. Sanders Prototyping (SP) was used to fabricate a variety of 2-2 PZT-5H/Spurr epoxy composites with linear, gaussian and exponential gradients. Based on the modeling results and vibration profiles, the linear 2-2 gradient showed the lowest off-axis sensitivity. Fused Deposition of Ceramics (FDC) was also used to build curved piezoelectric composite transducers for focusing the beam in medical imaging applications. These composites had good electromechanical properties with a k_t of 68% and an average d₃₃ of 400 pC/N. The processing and electromechanical properties of the VFG and curved composite transducers are discussed here