Simulation and Fabrication Process for a Medical Phased Array Ultrasonic Probe using a 0.91Pb(Zn_1/3Nb_2/3)O₃–0.09PbTiO₃ Single Crystal

Abstract

Medical array ultrasonic probes using a 0.91Pb(Zn 1/3 Nb 2/3 )O 3 -0.09PbTiO 3 (PZN-PT) single crystal exhibiting a high electromechanical coupling factor ( k 33 ) >90% have been studied in order to realize both a higher sensitivity and broader bandwidth properties. Pulse echo characteristics of the array probes, each transducer of which has dimensions of 6.0 mm×0.14 mm with a center frequency of 3.5 MHz, are simulated using the dielectric and the piezoelectric constants of the grown PZN-PT single crystals. Simulated echo amplitudes of the PZN-PT probes have been improved by as much as 7 dB compared with those of the conventional Pb(Zr 1- x ,Ti x )O 3 (PZT) ceramic ones. Moreover, the bandwidth of the PZN-PT probe is expected to be about 25% broader than those of the conventional PZT probes. It has been shown by simulation that the low acoustic impedance as well as the high coupling factor of the PZN-PT crystal contribute in broadening the bandwidth of the probe. The fabrication process of the array probe was investigated. A conventional method in which the dicing conditions are optimized and a novel dicing process are proposed.