Novel multi-layer-composites design for ultrasonic transducer applications

High quality ultrasonic transducers require high sensitivity and broad bandwidth to achieve high contrast and high spatial resolution ultrasonic imaging. Multi-layer-composites transducers were proposed, which facilitated high sensitivity and broad bandwidth. Multi-layer-composites were designed by W.A. Smith theory, simulated using finite element analysis based PZFlex software and fabricated using dice and fill method. 5 MHz transducers were fabricated and both electrical and acoustic properties of the transducers were characterized systematically. The multi-layer-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 (166.18 mV) compared to large pitch 1–3 composites transducers (4.605 MHz, 38.9%, and 98.74 mV, respectively) and small pitch 1–3 composites transducers (4.695 MHz, 46.6%, and 88.2 mV, respectively). These results suggest that multi-layer-composites have great potential in ultrasonic transducer applications. A theory was proposed to approximate the sensitivity, which has potential in guiding the design of multi-layer-composites transducers.