Fabrication and modeling of piezoelectric transducers for High-Frequency medical imaging

TL;DR

This study develops a method for fabricating high-frequency PZT piezoelectric transducers using electrophoretic deposition and sintering, resulting in uniform thick films suitable for medical ultrasound imaging at around 20 MHz.

Contribution

It introduces a novel fabrication process combining electrophoretic deposition and sintering to produce uniform PZT thick films for high-frequency ultrasound applications.

Findings

Uniform PZT thick films with controlled thickness and density were achieved.

The transducers exhibit a resonant frequency around 20 MHz.

The films demonstrate suitable electrical and mechanical properties for medical imaging.

Abstract

We have studied the processing of piezoelectric thick films using electrophoretic deposition (EPD) for high-frequency ultrasound applications. Lead-zirconium-titanate (PZT) particles synthetized by solid states synthesis were dispersed in ethanol using ammonium polyacrylate (PAA). The electrophoretic deposition of PZT particles was performed at a constant-current mode. PZT thick-films deposited at 1 mA for 60 seconds were sintered at 900oC for 2 hours in a PbO-controlled atmosphere. The scanning-electron microscopy (SEM) analysis shows that the thickness of PZT layer is uniform and that the pores are homogeneously distributed within the layer. The complex electrical impedance was measured and fitted by KLM scheme in order to deduce the dielectric, mechanical and piezoelectric parameters of the thick-films. The density and thickness of PZT thick films are used as inputs and the thickness coupling factor kt, dielectric constant at constant strain and resonant frequency are deduced. The results show that homogeneous PZT thick-film structures with tailored thickness and density prepared by EPD and sintering having a resonant frequency around 20 MHz can be used for noninvasive medical ultrasound imaging and diagnostics.