Design and Characterization of Acoustic Matching Layers for Piezoelectric Ultrasonic Transducers
Date Issued
2007
Date
2007
Author(s)
Ko, Chung-Ting
DOI
en-US
Abstract
A novel active matching layer made of lead zirconate titanate (PZT) plate has been developed as an “impedance matching layer” for high-intensity focused ultrasound (HIFU) applications. The PZT matching layer redistributes the frequency spectrum of an original broadband ultrasonic probe, and acts as a frequency filter without reducing the wave amplitude. These behaviors are contributed to electromechanical and mechanical properties at the PZT matching layer, and are investigated in this study by a series of experiments on PZT matching plates with different electromechanical properties and polarization and surface charge conditions.
Traditional passive matching layers, such as ceramic-polymer composites, are also studied. Three different ceramic-epoxy composite are developed and their impedance properties studied. Among the three, the zirconium oxide-epoxy composite exhibits a tolerable attenuation level and an optimum impedance value. It is then integrated on to a home-made HIFU transducer to test its effectiveness. The beam profile of the matched HIFU transducer is characterized by a hydrophone, and an in-vivo experiment is carried out to gauge its performance.
In this study, structure materials such as porous ceramics and porous ceramic-epoxy composites are also proposed as candidate materials for impedance matching for water and human tissues due to their low attenuations and impedances.
Subjects
聲阻匹配層
濾波
複合材料
孔洞陶瓷
Acoustic matching layer
Filtration behavior
HIFU
Composites
Porous ceramics
Type
thesis
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