PZT/epoxy multi-composites for ultrasonic transducer applications

High quality ultrasonic transducers require high sensitivity and broad bandwidth to achieve high contrast and high spatial resolution ultrasonic imaging. PZT/epoxy multi-composites transducers were proposed, which facilitated high sensitivity and broad bandwidth. The design of the PZT/epoxy multi-composites were guided by W.A. Smith for high sensitivity. Finite element analysis based PZFlex simulation was utilized to predict the performances. The PZT/epoxy multi-composites were fabricated using a modified dice and fill method. 5MHz transducers were fabricated using the PZT/epoxy multi-composites and two types PZT/epoxy 1–3 composites with the same fabrication process. Electrical and acoustic properties of the transducers were characterized systematically. We determined that the PZT/epoxy multi-composites transducers have a little larger center frequency(5.03 MHz), similar −6 dB bandwidth(40.6%) and a much higher peak-to-peak voltage(166.18mV) compared to large pitch PZT/epoxy 1–3 composites transducers (4.605 MHz, 38.9%, and 98.74mV, respectively) and small pitch PZT/epoxy 1–3 composites transducers (4.695 MHz, 46.6%, and 88.2mV, respectively). These results suggest that PZT/epoxy multi-composites have great potential in ultrasonic transducer applications. A theory was proposed to approximate the sensitivity at last, which has potential in guiding the design of M type transducers.