Simulation And Theoretical Analysis Of Ultrosound Microfluidic Mixer

With the extensive application of Micro-electromechanical System (MEMS) in the domain of BME, fluid driving and mixing technique has become one of the research hotspots of MEMS technique. Microfluidic mixer is a microfluidic device that has an extensive application in chemical reaction, biochemical sensor, and DNA sequencing in the future. Ultrasonic microfluidic mixer adopt the ultrasonic vibration, generated by the anti-piezoelectric effect of piezoelectric ceramics, excites the ultrasonic wave, and generates acoustic field simultaneously. The movement of the fluid medium in the mixer will be disordered in the effect of acoustic radiation pressure. Ultrasonic wave Microfluidic mixer has several advantages for extensive application in the future, such as non-movable components, needing lower driving voltage, convenient controlling method, fitting for miniaturization and so on.Firstly, the dissertation summarizes the development of MEMS and micro-fluid, makes an introduction of the present kinds of micro-fluid driving and control technique, and makes a description on the situation of the microfluidic mixer at home and abroad at present. The anti-piezoelectric effect, material character and frequency character of piezoelectric ceramics are introduced. The synthesis of standing wave is analyzed in detail. Through the study on the mechanism of acoustic radiation pressure, the basic theory of the ultrasonic wave driving the fluid to mix is obtained.Secondly, the theory of microfluidic mixer finite element analysis (FEA) method is introduced. The piezoelectric ceramic FE model is built based on FE method. The coupling field analysis, modal analysis theory and harmonic response analysis theory are introduced. And the basic equations of ideal medium, acoustic wave FEA theory and the acoustic-structure coupling theory are expatiated.Thirdly, the microfluidic mixer model is built by using finite element analysis software ANSYS. By the modal analysis, the nature frequencies and vibration modes are obtained, and the relationship between model natural frequencies is discussed. By the harmonic response analysis, the desired vibration mode is excited and the frequency characteristic is identified. By the transient response analysis, the movement of the disc piezoelectric vibration is obtained after applied AC voltage. The microfluidic mixer cavity model is built in the ANSYS Workbench, Choosing water as the fluid medium, make fluid-structure coupling analysis on the microfluidic mixer the streamline in the mixer is obtained, the disturbance of the flow is shown. Simulate the mixing experiments of water of different temperature, analyze the mixing result, the capability of the mixer can be checked. Filling ethanol and glycerol together in the mixer, carry out simulation, the distribution of density in the mixer is obtained, the mix situation of the fluid inner the model can be observed through the results. It provides guidance for the dynamic characteristics, mix of micro-fluid and optimization the structure design of the cylindrical mixer.