Acoustic Energy Transmission Study Of Imperfect Acoustic Impedance Matching

This dissertation focuses on the acoustic energy transmission of imperfect matching layers.It focuses on the analysis of the acoustic energy transmission in the case of bulk acoustic wave sensors under imperfect matching and soft matters surrounded by hard shells.The full text is divided into five chapters.The first chapter and the fifth chapter are the introduction,the summary and the prospect.The second chapter analyzes the relevant theory of the thin film bulk acoustic wave sensor.The third chapter studies acoustic energy regulation of the soft matters surrounded by hard shells under the imperfect acoustic impedance matching.The fourth chapter studies the imperfect impedance matching structure of the bulk acoustic fluid sensor and the optimization of the sensor's sensing performance.The main contents are:1.Theory of multilayer piezoelectric acoustic wave deviceIn the second chapter of the dissertation,Mason model and transmission line model are introduced firstly.Taking two-layer and three-layer piezoelectric acoustic structures as examples,Mason model and transmission matrix method are used to analyze and calculate the input impedance curves of the two structures respectively.2.Study on acoustic energy transmission of soft matters surrounded by hard shells based on imperfect acoustic impedance matchingIn the third chapter of the dissertation,we analyze the reality of impedance matching in complex acoustic structures,and propose an optimization method,namely through imperfect acoustic impedance matching methods to control the transmission of acoustic energy in complex acoustic structures.In the study,we studied the ultrasound detection of human brain soft tissue and equated it with soft matters surrounded by a hard shell.The imperfect acoustic impedance matching effectively transmits acoustic energy to soft matters surrounded by a hard shell.3.Structural design and performance optimization of bulk acoustic wave liquid sensorThe BAW liquid sensor is studied by designing imperfect acoustic impedance matching to allow acoustic energy to pass through the microfluidic channel and into the Si substrate.Using the low loss characteristics of the Si substrate,the resonant Q of the sensor device is increased,and the sensing accuracy of the sensor is improved.Through structural optimization,we obtain a Q up to 300 for liquid sensors.The final part of the dissertation is a summary of the full text and the outlook for future work.