| In the past few decades, Micro-electro-mechanical System (MEMS) developed rapidly. As an important branch of MEMS, micro-fluid technology has been widely used in Biomedical engineering, chemical pharmaceutical, biological detection, food safety, and other fields. Due to the effect of the scale of the fluid, the traditional electric pressure driving is not suitable for the development of micro fluidic objects, exploring more efficient micro fluid driving and control technology which is based on microscale is gradually become a hot research topic. Micro pumps based on different methods are designed and some of them have already quite mature. In micro-fluid system, the common micro pumps contain valve micro pumps and valveless micro pumps, while the valve micro pumps which have been widely used get more mature than other. However, due to the presence of movable parts invalve micro pumps, its miniaturization and service life has been limited. Common driving methods used in valveless micro pumps contain electroosmosis drive, thermally drive, solenoid drive, electrostatic drive and so on. Although they have solved microminiaturization and the problem of service life to a certain extent, they still face a large number of technical problems.According to the above problem, this paper puts forward a new type of micro fluid drive and control technology, which is ultrasonic traveling wave micro-fluid driving and control. It changes the traditional micro fluidic driving point pressure drive to surface pressure drive. Due to the inverse piezoelectric effect of the piezoelectric ceramics array on the pump, the pump wall deforms and generates traveling wave and the mass point of the wall moves in an elliptical orbit. The liquid inside the pump generates net flow in the outlet of the micro pump as a result of wall adhesion force, liquid molecular inter-atomic forces, acoustic streaming and acoustic radiation pressure. Ultrasonic traveling wave micro pump has a good controllability. The direction and velocity of the liquid can be easily changed through adjusting the amplitude, phase and frequency of the driven voltage. In addition, the action of the pump is gentle relatively and it contains no movable parts such as valves. It won’t damage cells or biological macromolecular structure characteristics in the biological fluid and it is expected to play its characteristics in the field of biochemical analysis and other fields. Based on the analysis of the principle of traveling wave driving we design a model of traveling wave driven micro pump. And we analyze the fluid-solid coupling of the model on the use of the finite element software COMSOL Multiphysics. We verify the feasibility of the micro pump through the analysis.This paper mainly divides into four parts. First of all, we introduce the state of MEMS development at home and abroad then give a short description of the application and progress of the micro fluid driving technology. In addition, we introduce several common micro pump and point out their advantages and disadvantages. Second, we analyze the material and frequency property of the piezoelectric ceramics, then deduce the principle of the mass point’s traveling wave and elliptical movement, and give a system description of the driving mechanism of ultrasonic traveling wave driving. After that, we introduce the common FEM method, fluid-structure interaction analysis theory and FEM software COMSOL Multiphysics. At the same time, We build the FEM model of the micro pump. At last, we make a detailed study of the basic movement and driven performance. And then we discuss the impact to the velocity in the outlet of the micro pump under the condition of driving voltage amplitude, frequency, viscosity of fluid power and coupling surface roughness changes. This can offer a reference to the next study of the ultrasonic traveling micro pump. |
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