Research On The Fluid Flow And Sample Mixing In The Microfluidic Devices

The study of fluid flow, heat and mass transfer in the microchip is mainly carriedout with the method of numerical simulation, then some practical problems associatedwith sample dispersion and mixing in microdevices are discussed in detail, and someuseful suggestions that may contribute to the quick commercialization of microchiphave been given out.In the first part of this paper, on the basis of the introduction of the backgroundof the study of sample dispersion and mixing in the microchip, the essentialexpressions and goveming equations about microflow have been given for someproblems which will be met in the study.In the second part, for the wide use of the conventional driving method ofpressure gradient in the classical fluid mechanics and analytical operations, someproblems are discussed as follows: the influence of fluid convection and the surface ofmicrochip on the dimension of diffusion in the pressure driven micro-channel flows;the relation between the fluid dispersion and secondary flow, the radius of curvedmicrochannel and Reynolds number; the fluid flow and heat transfer in themicrochannel with both electroviscous and thermalphyscial effect.In addition, with the development of microfluidic technologies, electroosmosisare widely used as a promising driving method for microflow, thereby, some problemsabout electroosmosis are also discussed as follows: the diffusion in the micro-channelflow driven by electroosmosis; the mixing in curved microchannels withheterogeneous surface potentials; the optimization of surface potential of curvedmicrochannel, which can effectively weaken the axial dispersion of sample bandcaused by Joule heating and curved effect; the efficiency of mixing in heterogeneousmicrochannels with patterned surface potentials.