The Study On Wireless Energy Transfer Based On MEMS Piezoelectric Ultrasonic Transducer

With the continuous development of wireless communication maturity of IC processing technology,growing number of researchers have paid attention to the application of MEMS devices in military and implantable medical fields.implantable medical devices will bring a high cost to replace the batteries due to the special working environment of the device.Moreover,battery replacement can not be realized in some cases,which will affect the normal work of the devices.The piezoelectric micromachined ultrasonic transducers(pMUTs)based on AIN(aluminum nitride)material can realize the transformation,between mechanical energy(ultrasonic wave)and electric energy by utilizing the piezoelectric characteristics of materials,so as to realize wireless power supply for devices.There are 6 chapters in this thesis and they are organized as follows:In chapter 1,the research background of the topic,the development of MEMS technology and the advantages of MEMS technology are introduced,the three different ways of converting vibrationa mechanical energy into electrical energy and their respective working principles are also introduced.Then the research status of wireless energy transmission china and abroad is introduced respectively.Finally some basic theoretical knowledge about ultrasonic,the main research content and research methods of the topic are put forward.In chapter 2,the basic working principle of pMUT is introduced.The performance of various piezoelectric materials is compared,and the method of piezoelectric materials and their kinetic energy converted into electrical energy is proposed.Then the simulation of the process of acoustic emission by.the ultrasonic transmitter,which includes the distribution of sound pressure,sound pressure intensity and stress distribution is conducted through the COMSO Multiphysics finite element simulation software.Based on the previous analysis,the two types of wireless energy transmission units square pMUTs and round pMUTs are designed.Meanwhile,the finite element simulations of square devices and round devices are performed to obtain the first order to sixth-order vibration modes,device stress distribution,resonant frequency and impedance parameters.In chapter 3,the micromachining process of a square device is described in detail.Then,a pMUT device is fabricated by MEMS technology.The pMUT has a complete structure and meet the requirement of the design.The fabricated device can be used for testing.In chapter 4,the test setup of the pMUT is demonstrated,and a series of experiments are carried out on the single square pMUT device and the single circular pMUT device.A simple comparison is made between the performance of a single square pMUT device and a single circular pMUT device.The experimental data is then analyzed to determine the natural frequency and impedance of the pMUT,as well as the output voltage and output power of the device in atmosphere,deionized water,and pork tissue.At the same time,the experimental data is compared with the simulation data obtained previously.In chapter 5,the similar experiments are conducted on.the pMUT array,and the performance characterization parameters such as output voltage in atmosphere,deionized water,and pork tissue are obtained.In chapter 6,the main work of this thesis is summarized.Some of the problems and deficiencies encountered in this paper are analyzed briefly.At last,the future work of this research is discussed.