Study of 1-3 Piezocomposites for High-Intensity Focused Ultrasound Transducers

• Main Authors: Hsin-Chih Liu, 劉信志
• Other Authors: Yu-Li Lin
• Format: Others
• Language: zh-TW
• Published: 2011
• Online Access: http://ndltd.ncl.edu.tw/handle/92603563808195384735

碩士 === 中華大學 === 機械工程學系碩士班 === 99 === Piezocomposites with 1-3 connectivity have been extensively used in medical imaging transducers and high-intensity focused ultrasound transducers, but most studies of 1-3 piezocomposites were done for medical imaging applications. In this study, 1-3 PZT4-epoxy composite focused transducers with various aspect ratios and volume fractions were constructed in-house for the evaluation and analyses of coupling factor, dielectric tangent loss, mechanical quality factor, bandwidth, acoustic impedance, vibration crosstalk, and electro-acoustic efficiency. The experimental results demonstrated that although the coupling factor of composite transducers (0.60 to 0.68) was higher than that of the ceramic transducer (0.49), the composite transducers had a low efficiency (57% to 69%) compared to the ceramic transducer (87%) due to the high dielectric loss and high mechanical energy loss of the composites. The bandwidth (0.16 to 0.19 MHz) and acoustic impedance (14.6 to 23.8 MRayls) of composite transducers were superior to the ceramic transducer (0.10 MHz & 35.1 MRayls). For the composite transducers, the efficiency and acoustic impedance were inversely proportional to the aspect ratio and proportional to the volume fraction. The vibration crosstalk between PZT rods could be increased to significantly decrease the efficiency of the composite transducer when the PZT-rods spacing was 0.1 mm at 1.0-MHz resonance. With an optimal design of the aspect ratio, volume fraction and PZT-rods spacing, the maximum efficiency of the composite transducer can be achieved.