Optimization Design of Ultrasonic Transducer With Multimatching Layer

An optimization design strategy is developed for ultrasonic transducer (UT) with multimatching layer to improve its performance. The piezoelectric equivalent circuit model is used to determine the optimization interval of matching layer, and the PiezoCAD software is used to simulate the performance of UT with multimatching layer. The neural network (NN) models are trained by the simulation data to characterize the relationship between the thickness of matching layer and performance of UT. Then, the multiobjective optimality criteria for UT is established based on its performance parameters, including center frequency (CF), -6 dB bandwidth (BW) and pulsewidth (PW). The thickness of matching layer is optimized by particle swarm optimization (PSO) algorithm. According to the designed performance, the optimized copper thickness and parylene thickness are about 17.76 and 23.05 μm, respectively. The simulation results of UT with the optimized multimatching layer well agree with the designed targets. Also, CF, -6 dB BW, and PW of the fabricated UT with the optimized multimatching layer are 5.672 MHz, 50.08%, and 0.295 μs, respectively, which nearly achieve the designed performance. In addition, the performance of UT with the optimized multimatching layer is much better than that of UT without matching layer. Moreover, compared with UT with single or double matching layers determined by the quarter wavelength theory, the UT with the optimized multimatching layer has better comprehensive performance. Finally, the fabricated UT with the optimized multimatching layer is used to measure the thickness of testing block, and the relative errors are all less than 1.0%, which implies that the optimized UT has excellent performance.