High frequency single element transducer based on pad-printed lead-free piezoelectric thick films

Abstract

A transducer for medical imaging was fabricated using a pad-printing process to deposit a curved lead-free thick film (KNN-based) on an electroded backing (porous KNN). First, the electromechanical properties of the pad-printed thick film were measured. An effective thickness coupling factor of 34% (similar to those obtained with the same composition by a screen-printing process) was obtained. The transducer has a f-number of 1.3 and a focal distance around 5 mm. The center frequency is at 12 MHz and the -dB bandwidth is 93% and a high sensitivity is observed. For the first time, images of human skin in vivo were obtained using a lead-free film. They are compared to those obtained with a PZT-based transducer.

Advanced Synthesis on Lead‐Free KxNa(1−x)NbO3 Piezoceramics for Medical Imaging Applications

“…Levassort et al prepared a transducer (Figure a) for medical imaging based on a lead‐free thick film. The KNN thick film, sintered at relative lower temperature of 200 °C, were deposited using a pad printing technology on the electrode backing also made by KNN.…”

Small Reduction of the Piezoelectric d33 Response in Potassium Sodium Niobate Thick Films

“…An unmodified KNN bulk ceramic was reported to have a piezoelectric d 33 coefficient between 80 and 120 pC/N. In general, the processing and functional properties of KNN thick films have been studied to a much lesser extent [9][10][11][12][13][14][15][16] in comparison with KNN thin films and bulk ceramics. 7 Taking into account their other properties, for example, density, longitudinal sound velocity, dielectric constant, mechanical, and dielectric losses, Tran-Huu-Hue et al 8 reported that KNN materials are suitable for high-frequency applications.…”

Lead-free piezoelectric materials and ultrasonic transducers for medical imaging

“…[86][87][88] A 50 MHz transducer utilizing LiNbO 3 crystal was fabricated and characterized by Snook et al 85 In addition, its performance was compared to other transducers based on 1-3 PZT fiber composite, PVDF, and PbTiO 3 . Tables 10 and 11 present a summary of design parameters and the measured acoustic results for these transducers.…”

“…84 Levassort et al employed this method to prepare a curved high frequency KNN-based transducer. 85 In this process, a machined KNN porous cylinder with radius curvature of 5 mm was used as the backing material. Then a KNN-based piezoelectric thick film was deposited by pad-printing technique.…”