Influence Of Microfluidic Channel's Form Error On Species' Separation Effect

The research of microfluidic chips is a new multi-disciplinary field. It's also the important development frontier in the field of analytical science, MEMS, life science, chemical synthesis, analysis instrument, environmental science and etc in the new century. With the microchannels as network, it connects micro-pump, micro-valve, micro-reservoir, micro-electrode, micro-detecting-element, and so on, which have the ability of transferring light, electricity and fluid. In a word, microfluidic chips belong to the micro-total-analysis-systems, which merges the analysis function of injection, dilution, reagent stock, reaction, separation and detection as a whole to the most extent.During the manufacturing and applying process, it seems to be unavoidable that there are form errors and flaws on the surface of microchannels, which broaden the concentration zone and influence the reappearance for the same or different chips and detecting precision. However, the present researche is all about ideal structure. So far, there is no systemic research about the influence of microchannel's form error when micro-fabricating on electrophoresis separation.This article studies the problem-"Influence of Microfluidic Channel's Form Error on Species' Separation Effect" all-sidedly and detailedly. Based on the understanding of microfluidic transfer mechanism in detail, a series of microchannel models with form error were constructed under the help of MEMS simulation software-CoventorWare, as well as the Peak Height and Full-Width-Half-Maximum of species were simulated and calculated after they flew through the different form error areas. All these result in that the form error of microchannels represented by convergent and divergent angle influences the separation effect of species differently, and there is a turning point about the influence degree. Meanwhile, based on the micromachining process about glass microfluidic chip, two glass chips were fabricated. Each of them has four cross channels, which represent eight different form error to typical angle degree. Microfluidic analysis experiment was carried out on the "fluid dynamic observation platform for microfluidic chip" with the two chips, whose aim is to research the influence of glass channel's form error on species' flow and separation effect. After the experiment data was recorded and analyzed and compared with that of calculation results from software, it is found that the data of experiment is as good as the one of simulation. Therefore, the influence of microchannel's form error on species' separation effect, as well as the regular result, is verified.After making a comprehensive analysis on the results from experiment and simulation, it can be concluded that the form errors of microchannel represented by divergent and convergent angles influence the flow and separation of species very much. With the increase of convergent angle, Peak Height and FWHM of species increases and decreases respectively. However, with the increase of divergent angle, the varying tendency is reverse. Meanwhile, with the increase of convergent (divergent) angle, there is a turning point about the Peak Height and FWHM of species: when the convergent (divergent) angle is smaller than 15 degree, Peak Height and FWHM will vary dramatically with the increase of angle; however, when the convergent (divergent) angle is bigger than 15 degree, Peak Height and FWHM will keep steady. This finding has an important guiding significance to get a deeper understanding of Influence of Microfluidic Channel's Form Error on Species' Separation Effect, to control effectively the scope of form error during manufacture, to evaluate microfluidic chips' channel quality, etc.