Design and comparison of PMN-PT single crystals and PZT ceramics based medical phased array ultrasonic transducer

The design, fabrication and comparison of PMN-PT single crystals and PZT ceramics based 3 MHz phased array ultrasonic transducers were investigated. The resonance mode and electromechanical properties for PMN-PT single crystal were simulated by using the COMSOL Multiphysics software. Simulation results indicate that the electromechanical coupling coefficient k33' keeps at 0.86-0.87 when the aspect ratio G < 0.7, as well as a pure height-extensional mode was obtained. Two types of ultrasonic phased arrays using PMN-PT single crystal and PZT ceramic were fabricated and compared. The experimental results revealed that more than 27.7% broader -6 dB bandwidth, 5.2 dB higher relative sensitivity, and shorter pulse length can be obtained by using PMN-PT single crystal compared to the PZT array. The experimental results agreed well with the predictions of simulation by using the PiezoCAD software. Furthermore, PMN-PT array has the same good consistency of the performance as the PZT array, while the better acoustic performance and higher electromechanical properties compared to PZT array as a whole. In the end, the ultrasonic imaging which uses the PMN-PT based array transducer has the better definition, the higher axial resolution and lateral resolution compared to those of PZT based array transducer.