Fabrication and Characterization of High-Frequency Ultrasound Transducers Based on Lead-Free BNT-BT Tape-Casting Thick Film.

Junshan Zhang,Yi Quan,Qifa Zhou,Chunlong Fei,Xiaoqing Wu,Wei Ren,Yantao Liu

doi:10.3390/s18093166

Abstract

A lead-free 0.94(Na0.5Bi0.5) TiO3-0.06 BaTiO3 (BNT-BT) thick film, with a thickness of 60 μm, has been fabricated using a tape-casting method. The longitudinal piezoelectric constant, clamped dielectric permittivity constant, remnant polarization and coercive field of the BNT-BT thick film were measured to be 150 pC/N, 1928, 13.6 μC/cm2, and 33.6 kV/cm, respectively. The electromechanical coupling coefficient kt was calculated to be 0.55 according to the measured electrical impedance spectrum. A high-frequency plane ultrasound transducer was successfully fabricated using a BNT-BT thick film. The performance of the transducer was characterized and evaluated by the pulse-echo testing and wire phantom imaging operations. The BNT-BT thick film transducer exhibits a center frequency of 34 MHz, a −6 dB bandwidth of 26%, an axial resolution of 77 μm and a lateral resolution of 484 μm. The results suggest that lead-free BNT-BT thick film fabricated by tape-casting method is a promising lead-free candidate for high-frequency ultrasonic transducer applications.

Highlights

Ultrasound imaging system have been widely used for imaging soft tissues, blood vessels, skin and eyes [1,2,3,4], in which ultrasound transducers transmit ultrasound waves into the tissues and receive the resultant echo waves
The P-E hysteresis loop of BNT-BT thick film is presented in Figure 5, which indicates that the hysteresis loop is well saturated, and the remnant polarization Pr and coercive filed Ec are 13.6 μC/cm2 and 33.6 kV/cm, respectively
The P-E hysteresis loop of BNT-BT thick film is presented in Figure 5, which indicates that t teresis loop is well saturated, and the remnant polarization Pr and coercive filed Ec are 13.6 μC/c

Summary

Introduction

Ultrasound imaging system have been widely used for imaging soft tissues, blood vessels, skin and eyes [1,2,3,4], in which ultrasound transducers transmit ultrasound waves into the tissues and receive the resultant echo waves. As the key component of ultrasound imaging system, ultrasound transducers determine the spatial resolution of the imaging system. High frequency and broadband ultrasound transducers have been desired for clinical and biophysical applications [5,6], because they can generate narrow ultrasound beams and have superior spatial resolution [7]. The fabrication of high-frequency ultrasound transducer is strictly reliant on the technology level of the piezoelectric materials and manufacturing techniques. It is well known that the selection of piezoelectric materials has a significant influence on the performance of high-frequency transducers

Methods

Results

Conclusion