Optimizing dual-piezoelectric-layer ultrasonic transducer via systematic analysis

Abstract In order to optimize the center frequency and bandwidth characteristics of the dual-piezoelectric-layer ultrasonic transducers, an investigation was conducted to find the optimal connection and material combination methods between piezoelectric layers for a dual-piezoelectric-layer structure utilizing systematic comparison and analysis. Finite element analysis (FEA) simulation results show that among all the connection methods, the one based on inversion layer technique exhibits the greatest performance. The simulation results also show that when a PMNT single crystal plate is used as the first piezoelectric layer and a PZT ceramic plate is used as the second piezoelectric layer with a thickness ratio of 7.5:2.5, the transducer presents about 16 % higher center frequency and 50 % broader −6 dB bandwidth as well as a shorter −6 dB lateral beam width compared with a conventional single-piezoelectric-layer transducer. The measurement results prove that the transducer with the proposed structure exhibits the greatest performance, which obtains about 42 % higher center frequency and 10.4 % broader −6 dB bandwidth compared with a conventional transducer. In the meanwhile, the proposed transducer has the shortest pulse length as well. These characteristics are conducive to improving the lateral and axial resolution of ultrasound imaging.