面向水下成像应用的微电容超声波换能器线阵设计与测试

发布时间：2018-11-16 12:44

【摘要】：超声成像技术在医学诊断、无损检测、超声显微镜和水下探测等多个领域内具有广泛的应用前景。超声波换能器是超声成像设备的核心部件，传统的压电式超声波换能器由于种种限制已不能满足现代超声检测的需求，而新型的电容式超声波换能器（CMUT）以其灵敏度高、频带宽、与介质阻抗匹配及适合制造集成阵列等优势已逐渐成为各国的研究热点，被认为是下一代超声传感器的发展方向。本文在研究了超声成像理论的基础上，结合现有的加工技术，设计了适用于水下超声成像的一维16元CMUT线阵，并针对线阵的设计、加工、封装及性能测试等开展了较为详细的研究，具体研究内容如下：（1）对超声成像换能器阵列辐射声场及指向性问题进行了研究；分析了一维线阵声束的聚焦、偏转，并对影响超声成像图像质量的空间分辨率和伪像问题进行了简单的研究分析。（2）根据ANSYS有限元仿真确定了敏感单元的结构尺寸以及工作电压、塌陷电压、静态电容、变化电容和输出电流等性能参数；在敏感单元的设计基础上，研究了阵元间距、阵元宽度及阵元数目对一维线阵指向性的影响，，并确定了一维线阵的结构参数。（3）结合现有的加工工艺水平及实验室前期的加工经验，优化了基于硅-硅键合的加工工艺路线并完成了一维CMUT线阵的加工；针对换能器线阵面向水下应用的需求，设计了防水性能和透声性能良好的封装外壳。（4）对线阵的表面形貌进行了简单测试，测试发现器件的实际尺寸与设计尺寸基本相符，验证了加工流程的准确性和可行性；对超声波换能器发射和接收超声波的性能进行了测试，并研究了直流偏置电压和交流激励电压对换能器发射性能的影响；最后利用一维CMUT线阵进行了初步的成像实验，得到了水下目标图像，实现了水下成像的应用初探。
[Abstract]:Ultrasonic imaging technology has been widely used in many fields, such as medical diagnosis, nondestructive testing, ultrasonic microscope and underwater detection. Ultrasonic transducer is the core component of ultrasonic imaging equipment. The traditional piezoelectric ultrasonic transducer can not meet the needs of modern ultrasonic detection due to various limitations, while the new capacitive ultrasonic transducer (CMUT) has high sensitivity. The advantages of frequency bandwidth, matching with dielectric impedance, and suitable for manufacturing integrated arrays have become the research hotspot in many countries, and are considered to be the development direction of next generation ultrasonic sensors. In this paper, based on the research of ultrasonic imaging theory and combined with the existing processing technology, a one-dimensional 16-element CMUT linear array for underwater ultrasonic imaging is designed, and the linear array is designed and processed. Packaging and performance testing are studied in detail. The main contents are as follows: (1) the acoustic field and directivity of ultrasonic imaging transducer array are studied. The focusing and deflection of one dimensional linear array sound beam are analyzed, and the spatial resolution and artifacts which affect the image quality of ultrasonic imaging are simply studied and analyzed. (2) according to the ANSYS finite element simulation, the structure size, the working voltage, the collapse voltage, the static capacitance, the variable capacitance and the output current of the sensitive unit are determined. Based on the design of sensitive elements, the effects of array spacing, element width and number of elements on the directivity of one-dimensional linear array are studied, and the structural parameters of one-dimensional linear array are determined. (3) based on the existing processing technology level and the experience in laboratory, the process route based on silicon-silicon bonding is optimized and the one-dimensional CMUT linear array processing is completed. In order to meet the need of underwater application of transducer linear array, a package with good waterproof and sound permeability was designed. (4) the surface morphology of the linear array is simply tested, and it is found that the actual size of the device is basically consistent with the design size, which verifies the accuracy and feasibility of the machining process. The performance of ultrasonic transducer was tested, and the effects of DC bias voltage and AC excitation voltage on the performance of ultrasonic transducer were studied. Finally, a preliminary imaging experiment is carried out using one dimensional CMUT linear array, and the underwater target image is obtained, which realizes the application of underwater imaging.
【学位授予单位】：中北大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TB552

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