Simulation and Fabrication of PMN-PT Single Crystals Phased Array Ultrasonic Transducer Based on Alternating and Direct Current Poling

In this paper, the design, fabrication and comparison of Pb(Mg
_1/3
Nb
_2/3
)O
₃
-0.25PbTiO
₃
(PMN-0.25PT) single crystals (SCs) by alternating current poling (ACP) and direct current poling (DCP)-based 2.8 MHz phased array ultrasonic transducers were investigated. Pzflex finite element simulation was utilized to model and compare the electro-acoustic properties of ACP and DCP phased arrays. The finite element analysis (FEA) results indicated that the ACP phased arrays can exhibit a greater sensitivity, a broader -6dB@bandwidth, and a lower center frequency under the same acoustic structure and the same thickness of matching layers. In addition, the high coincidence of simulated and measured impedance proves the stability of the transducer fabrication processes. By comparing the permittivity of the SCs in the processes of transducer fabrication, it is shown that the ACP SCs are more sensitive to the clamping force during the pressurization process and to the cutting force during the dicing process, respectively. Compared with the DCP phased arrays, the ACP phased arrays have been shown to exhibit 7.90% increase in observed -6dB@bandwidth and 0.82 dB increase in relative sensitivity. These results suggest that ACP phased arrays can enhance both the longitudinal resolution and penetration depth of ultrasonic imaging. Finally, a typical phantom image is created to compare the imaging capabilities of ACP and DCP phased arrays. The findings indicate that phased arrays based on ACP PMNT SCs might be promising for medical ultrasound imaging applications.