Basic Research Of Ultrosonic Traveling Wave Microfluid Driving Technology

With the extensive application of MEMS technique in BME, fluid driving and controlling technique in the micron and nano components has become one research hotspot. The driving and controlling of microfluid is largely different from that of macrofluid. It is mostly because when the dimension decreases to micron level, the flow characteristic of fluid has changed a lot as a result of the influence of scale and surface effect. The change usually makes the transplantation of macrofluid driving and controlling technique to microfluid field unsuccessful or unfavorable, because microfluid driving and controlling technique is more complex and diversified. Ultrasonic traveling wave driving is different from the present microfluid driving techniques in principle. Using the anti-piezoelectric effect of piezoelectric ceramic, ultrasonic vibration is generated and the traveling wave is generated on the bottom surface of microchannel, which makes the particles of the bottom perform elliptic motions perpendicular to the channel surface, and acoustic field is generated simultaneously, and the liquid in the microchannel moves along the direction of traveling wave because of the collective effect of shearing Reynolds stress, acoustic radiation pressure, viscous force and molecular force. As a new microfluid driving technique, ultrasonic traveling wave driving technique has no movable components, needs lower driving voltage, can adapt to all kinds of environment, so it will has extensive application in the future.This dissertation is supported by Nation Nature Science Foundation of china (No.10572078) and Shandong Province Excellent Youth Scientist Foundation (No.2004BS05006). For the feasibility and driving model of ultrasonic traveling wave microfluid driving and controlling technique of the items, this paper has an embedded research from the view of dynamics analysis.Firstly, the status of microflow driving technique inside and outside the country is introduced, the mechanism of traveling wave's generation and elliptic motions are particularly analyzed, and the anti-piezoelectric effect, the character of material and frequency of piezoelectric ceramics, which makes a base for the driving and control of traveling wave microfluid, are also presented embeddedly. The relation between driving mechanism and model parameters is also given from the research on the forming mechanism of acoustic radiation pressure and acoustic streaming.Secondly, based on the analysis of the Finite Element Method (FEM), it discusses the relation between model's natural frequency and elastic body parameters, and analyzes how the channel size affects the natural frequency. By the harmonic response analysis based on the anti-piezoelectric effect, the anticipated vibration mode is successfully excited at the point of resonance frequency, and the frequency characteristic of response amplitude is obtained.Finally the objected-oriented programming is applied to finite element software for microfluid analysis. A frame of software (MFA) for microfluid analysis is implemented. The visual problem of processing the plane of FEM is discussed. And instances are also given to show the practicability of MFA at the finality of the paper.