高频聚焦超声换能器研制

	高频聚焦超声换能器研制
其他题名	DEVELOPMENT OF HIGH FREQUENCY FOCUSED SINGLE ELEMENT ULTRASOUND TRANSDUCER FOR MEDICAL APPLICATIONS
	刘鹏波
学位类型	硕士
导师	崔崤峣
	2015-10
学位授予单位	中国科学院大学
学位专业	机械工程
关键词	高频超声换能器聚焦 1-3型压电复合材料空间分辨率
摘要	医用超声换能器是整个超声成像系统的核心部件，其性能直接影响超声成像系统的图像质量。随着压电材料的发展，制作工艺的改进，计算机处理能力的提高，用于超声诊断的超声波频率也越来越高。高频超声换能器（中心频率>20MHz），尤其是高频聚焦超声换能器可以改善目标区域的成像分辨率，在超声生物显微镜（Ultrasonic Biological Microscope, UBM），光声成像（Photoacoustic Imaging, PAI），血管内超声成像（Intravascular Ultrasound，IVUS）以及小动物实验等领域，具有广阔的应用前景。本文利用PZT/Epoxy制备的高性能1-3型压电复合材料，通过对压电复合材料进行球面和柱面的塑形，成功研制了球面点聚焦和柱面线聚焦型超声换能器，主要工作包括以下几个方面： (1) 对超声换能器基本结构，各组件的材料及其特性进行分析以及分类研究，重点分析并研究了适合制作高频聚焦超声换能器的压电材料。结果表明，1-3型压电复合材料相比于单一相压电材料以其较高的厚度方向机电耦合系数、较低的声阻抗、相对较低的横向机电耦合系数、低介电常数、低机械品质因数、以及较好的柔韧性和可控性等性能而比较适合应用在高频聚焦超声换能器当中作为压电材料。 (2) 通过对W.A Smith等建立的1-3型压电复合材料的力学-声学特性理论模型进行仿真研究，得出压电相材料对1-3复合材料厚度振动机电耦合系数，声速，介电常数以及声阻抗等性能的影响。结果表明，当1-3型压电复合材料压电相材料的体积分数在30%~80%之变化时，复合材料机电耦合系数几乎为单一相压电陶瓷（一般为压电陶瓷）的1.5倍；介电常数随着压电陶瓷相的体积分数的增加而基本呈线性增加趋势；并且1-3型压电复合材料的声速随着压电相体积分数的增大而增大，增长趋势可为三段，其中在压电相体积分数小于30%时，随着压电相材料体积分数的增大，声速增长较快，当压电相体积分数介于30%~80%之间时，声速基本呈线性增长，当体积分数超过80%以后增长趋势重新增大。 (3) 通过Devaney-Levinc理论模型从理论仿真以及实验验证两方面研究了给声匹配材料RTV 615硅橡胶中掺杂不同体积分数的氧化铝细颗粒对其声速、声衰减、声阻抗等特性的影响和改变，对高频聚焦超声换能器的研制提供参考。 (4) 制备点聚焦和线聚焦两种不同自聚焦形式的自聚焦高频超声换能器，中心频率在50MHz附近，并对其时域波形以及声场特性进行了测试分析。经过测试，两种聚焦超声换能器，均具有较好的聚焦特性（聚焦深度<10mm）以及空间分辨率（横向和纵向的分辨率均小于200um）。对于目前医用超声在介入式诊断，浅表组织细微结构分辨，小动物实验以及光声成像等领域的应用具有重要的参考价值。
其他摘要	Medical ultrasond transducer is of vital importance in the whole ultrasonic imaging system, which can directly affect the image performance of the ultrasonic imaging system. As the development of piezoelectric materials, the improvement of production process and computer, the ultrasonic frequency of ultrasonic diagnosis is higher. High frequency ultrasond transducer (central frequency >20MHz), especially the high frequency focused ultrasound transducer can increase the imaging resolution of the target area. The High frequency ultrasound transducer has a broad application prospect in the Biological Microscope Ultrasonic (UBM), Photoacoustic Imaging (PAI), Intravascular Ultrasound( IVUS), small animal experiments and other applications. In this paper, the high performance 1-3 type piezoelectric composites were prepared. By shaping the piezoelectric composite materials the spherically and cylinder line focusing ultrasonic transducer were successfully fabricated. The main work included in this paper is shown as follow: (1) Firstly, the basic structure of ultrasond transducer, including the material and the characteristics of each component are analyzed and classified, The results show that the 1-3 type piezoelectric composites are more suitable for high frequency focusing ultrasonic transducers than the single phase piezoelectric materials, because of its high mechanical coupling coefficient, low acoustic impedance, low dielectric constant, low dielectric constant, low mechanical quality factor, better flexibility and controllability; (2) Secondly, the mechanical and acoustic properties of 1-3 type piezoelectric; composite materials is simulated based on the W.A Smith model. The results show that when the volume fraction is range from 30%~80% the mechanical and acoustic properties of the piezoelectric composite materials is changed. The electromechanical coupling coefficient is almost 1.5 times of a single phase piezoelectric ceramics (general piezoelectric ceramics), and the acoustic velocity increases with the increase of the volume fraction of piezoelectric ceramics phase; (3)Thirdly, the fine particles of alumina particles with different volume fractions is doped in RTV615 silicone rubber. And the acoustic properties such as the sound velocity, acoustic attenuation, acoustic impedance are both studied in a theoretical simulation based on the Devaney-Levinc model and the experimental verification; (4) At last, a self-focus high frequency (center frequency is near 50MHz) ultrasound transducer is fabricated. The time domain waveform and sound field characteristics are tested and analyzed. Results show that the two kinds of focused ultrasound transducer both have better focusing characteristics (focus depth <10mm) and spatial resolution (lateral and axial resolution are both less than 200um). For the future medical ultrasound diagnosis application such as distinguishing fine structure of the superficial tissue, the application of small animal experiment and photoacoustic imaging, the fabricated ultrasound transducer has an promising important application value.
语种	中文
文献类型	学位论文
条目标识符	http://ir.ciomp.ac.cn/handle/181722/49309
专题	中科院长春光机所知识产出
推荐引用方式 GB/T 7714	刘鹏波. 高频聚焦超声换能器研制[D]. 中国科学院大学,2015.

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