医学影像是临床医生对病人做出科学诊断的有力依据，而医学超声影像因为对人体没有伤害、简单易用、以及即时成像等优点而成为医学影像诊断中的重要手段。超声换能器是超声成像设备的核心器件。现有的超声探头大多基于硬质衬底制成，和人体的贴合不是很好，尤其是在一些医疗应用场景如需要实时观测心脏运动的手术中，贴合度不好的问题尤为突出，已经影响到了手术的顺利进行，因此有必要研究和人体皮肤贴合良好的柔性医用超声探头，以满足这种需求。本文针对这个问题，设计并实现了一种基于PZT体陶瓷和柔性材料构成的微超声换能器阵列，并进行了发射和接收信号测试。论文首先研究了医用柔性超声换能器阵列的可行性，并选择了压电性能较好的锆钛酸铅（PZT）陶瓷进行了有限元分析，确定了器件的工作模式和尺寸、厚度等参数，为了实现柔性特性，选取了多种柔性材料进行仿真，最后确定了用聚酰亚胺和聚二甲基硅氧烷作为传感器的衬底和保护层。论文之后研究了利用微电子的微加工工艺实现了超声换能器制作，其中的工艺主要包括将PZT陶瓷进行机械分割和激光切割探索、聚酰亚胺材料的图形化方法以及压电陶瓷片的极化方法等。由于在柔性材料上实现传统的半导体工艺，因此在光刻、显影、溅射金属剥离、刻蚀等关键工艺上都要进行可行性评估和参数优化，经过多次工艺探索之后，成功完成了基于PZT的医用超声换能器阵列的制备工作。将医用柔性超声器件极化和柔性封装后，我们对它进行了测试，测试内容主要包括阻抗测试、水中声学测试等，并将实验结果和仿真进行了比较。测试结果表明，论文研究的微超声换能器的谐振频率为2.3MHz附近，具有良好的机电耦合系数以及机械品质因数。在进行发射接收信号测试时，能够在水中和模拟人体的组织液中良好地实现收发信号，基本具备超声成像条件，满足医学上对超声换能器的要求。

Medical imaging is a powerful basis for clinicians to make scientific diagnosis of the patient. The medical ultrasound imaging is harmless and easy to use. It is also real-time imaging. All these characteristics made it an important method in the diagnosis. Medical ultrasonic transducer is the key part of medical ultrasound imaging equipment. Most of the traditional medical ultrasonic transducer based on hard substrate and usually they are made of a two-dimensional array. However it is difficult to adapt to the human body. The traditional micro ultrasonic transducer is also difficult to meet the special needs of implantable ultrasonic detection. To solve the above problems, this paper proposed a design of medical ultrasonic transducer array based on the PZT ceramic. The substrate of this transducer is PDMS and polyimide composite. So the transducer is flexible.The thesis firstly studied the feasibility of medical flexible ultrasonic transducer array, then we chose lead zirconate titanate (PZT) ceramics as the piezoelectric material for its good piezoelectric properties. Secondly this paper designed the structure of the transducer, the working mode of the device, and the parameters. The size, thickness and other parameters were also determined by simulation. To make the device flexible, this paper finally decided using polyimide and polydimethylsiloxane(PDMS) as the sensor substrate and the protective layer.This paper also studied the micro processing technology using micro realization of the ultrasonic transducer. The process mainly included the PZT ceramic machining and laser cutting, exploring the graphical method of polyimide materials and piezoelectric polarization method. Because the traditional semiconductor technology in flexible material is limited. So many experiments were designed to do research on the photolithography, polyimide etching and so on. After all these technic research, the flexible ultrasonic transducer was successful completed.The medical flexible ultrasonic devices was polarized and packaged by flexible material-PDMS. Then the device is tested. The test content included impedance measurement and underwater acoustics test. The test results show that the resonant frequency of the micro ultrasonic transducer was about 2.3MHz with good electromechanical coupling coefficient and mechanical quality factor. The experimental results and simulation are compared. In the transmitting and receiving signal testing, the signal is successfully detected by the microphone which means the ultrasonic transducer was functional and suitable for medical imaging.