Numerical Study Of Transport Process In Micro-mixers Based On Microfluidic Theory

Micro-mixer,by definition,is a micro unit with size within 10 to 300 ?m,mostly used in some delicate process such as,premixing,delivering,and processing of the samples.Its mixing capability determined the quality of the whole microchip.The micro-mixing delivery of the freezing microscope is an example of its application.In order to observe smaller and more complete structure in molecular scale.We need to achiever the even and disorder icy distribution for single molecular level in microseconds or even nanoseconds.Thus,the fast,effective,and stable mixing is one of the most important and prospective aspect of the micro-mixer research.In this paper,we analysis the development of the micro-mixer,research on the flow of the fluid and the mixing mechanism under the micro scale,and,based on the continuity theory,convection scattering effect and electrokinetic effects,construct the mathematical model for the pressure driven and Electro Osmosis driven micro-mixing process.We Construct the physics model for the butterfly-shape micro-mixer,and using the fluid field analysis program we analysis its transportation process,by comparison we find that 40 ?m is the best mixing depth of his mixer.By analysis the mixing level of different Re number,we find out the majority mixing mode for butterfly-shape micro-mixer is convection not diffusion.As the flow increase and,the mixing level of the mixer increase,and the time for mixing decrease;furthermore,the mixing time for 1?m/s is four times for the 6?m/s.However speed of the decrease of the mixing time is less than the increase of the increase of the flow.We Construct the physics model for the mixer,using numerical method simulate and compare the fluid field distribution,concentration variation and mixing level under different driven methods,inner structures,and different mixing places,and by observing the fluorescence of the glass micro-mixing chip.We compare the final result.The experimental shows that the fishbone-structure enhances mixing efficiency rapidly under the pressure driving and EOF driving,and we calculate and then plot the graph of chaotic enhancement for different flow and different mixing units,which consist with the experiment result;meanwhile,under same flow,respect to the pressure driving,EOF driving increase the mixing efficiency by 4%to 8%,and,by compare the flow speed of different driven method,analysis the reason of the different result of the two driven method.