Rearch Of A Miniature Peristaltic Micropump Based On Ultrasonic Travelling Driving

With the extensive application of Micro-electromechanical System (MEMS) in the domain of BME, micropump has become one of the research hotspots of MEMS technique. Miniature peristaltic micropump based on ultrasonic travelling wave is completely different from all the present micropump in principle. Using anti-piezoelectric effect of piezoelectric ceramic, ultrasonic vibration is generated and the traveling wave is generated on the bottom surface, which makes the particles of the bottom perform elliptic motions perpendicular to the channel surface. We synchronously excited two back-to-back piezoelectric ceramics rings whose polarization directions were opposite. Then two waves that are opposite in phase form a series of chambers between elastic bodies. The chamber volume changes with traveling wave and drives the fluid flow in the direction of the wave propagation. Miniature peristaltic micropump based on ultrasonic travelling wave has no movable components, needs lower driving voltage, and can be extensively used in many fields such as micro fluid heat dissipation, biochemical analysis and drug delivery.Firstly, the dissertation summarizes the development of MEMS and micro-fluid, and makes an introduction of the present micropump technique. The anti-piezoelectric effect, material character and frequency character of piezoelectric ceramics are introduced. The synthesis of traveling wave is analyzed in detail. Through the study on the mechanism of acoustic radiation pressure and acoustic streaming, the relationship between driving mechanism and model parameters is obtained, which is the basic theory of the ultrasonic traveling wave driving technique.Secondly, the basic idea of Finite Element Method (FEM) and ANSYS analysis flow was introduced. For the FEM analysis of miniature, ANSYS dynamic FEM and acoustics coupling analysis theory was introduced, including structure model analysis, harmonic response analysis, transient dynamic analysis and acoustics fluid-structure analysis.Thirdly, the FEM model of miniature peristaltic micropump was bulit to predict model inherent frequencies and modes by modal analysis. Mode B(0,5) was selected to perform harmonic response analysis and the amplitude-frequency response characteristics was obtained. The transient dynamic analysis was done to verify the feasibility of peristaltic micropump driving. For further fluid-structure analysis, acoustic-structure coupling analysis was performed to obtain vibration modes and inherent frequencies of the coupling model.Finally, transient dynamics analysis of the fluid-structure coupling model was completed to derive the fluid flow state. The FEM theory of fluid-structure coupling and MFX multi-field solver was introduced. Then the structure model and fluid model of miniature perstaltic micropump were established respectively in ANSYS and CFX and MFX multi-field solver was used to perform fluid-structure coupling analysis. Simulation results show that the model has a good effect on fluid driving and the maximum velocity in driving direction is 19.2mm/s. The model is continuing to be optimized to get better performance and efficiency.