Design and fabrication of non-periodic 1–3 composite structure for ultrasonic transducer application

Abstract

Piezoelectric composite materials (PCMs), combing the advantages of both piezoelectric materials and polymers, have been extensively used in piezoelectric material ultrasonic transducers (PCUTs). However, PCMs induce lateral modes in PCUTs, which can degrade their performance. In this study, a mathematical model for the lateral mode frequency was deduced. A novel 1–3 composite structure with non-periodicity in one dimension was designed based on the proposed model to eliminate the effect of the lateral mode. In addition, the PZFlex software was used to simulate and verify the performance of the PCUT. The non-periodic 1–3 PCM was fabricated and used to package 4 MHz PCUT. A PCUT with a normal 1–3 PCM was fabricated for comparison. Then, the electrical and acoustic properties of the PCUTs were then systematically characterized. The PCUT with the non-periodic 1–3 PCM had a broader −6 dB bandwidth (38.9 %), larger electromechanical coupling coefficient (0.68), higher peak-to-peak voltage (2.44 V) and smaller insertion loss (-17.40 dB) than those of the PCUT with normal 1–3 PCM (28.4 %, 0.55, 1.19 V and –22.86 dB). The results show that non-periodic 1–3 composite structure can break the limits of the lateral mode and has great potential for the development of high-performance PCUTs.