Research On Zeta Potential Modification Of Microchannel And Fluid Mixing Enhancement

The efficient mix of fluid in the micro channel is an important pretreatment process of sample analysis,which has the important application prospect in the field of oil analysis in the marine machinery device and ship pollutants detection that based on microfluidic technology.In this paper,a new method is proposed to change the zeta potential of PDMS channel wall by using polybrene(PB),and the zeta potentials of PDMS surface which was modified by polybrene(PB)solutions of different concentrations were obtained by the inductive zeta potential measurement method.On this basis,the influence of non-uniform zeta potential of the PDMS channel on the electroosmotic flow was studied by numerical simulation and experiment,and the influence of the zeta potential on vortex of fluid was found.Besides,the influence of non-uniform zeta potential on fluid mixing efficiency was studied.Specifically,the main research contents include:(1)The effect of different concentration of polybrene(PB)solution on the zeta potential was experimentally studied.An inductive zeta potential measurement system was built,and the zeta potentials on the surface of PDMS chip modified with different concentration of polybrene(PB)solution were measured.The results show that the zeta potential of the PDMS-Solution can be adjusted quantitatively by the polybrene(PB)solution.With the increase of the concentration of the solution,the zeta potential value of the modified PDMS-solution increases gradually.(2)The influence of non-uniform zeta potential of the PDMS channel on the electroosmotic flow was studied by numerical simulation and experiment.The model of the microchannel was established,and the influence of the distribution ratio of the non-uniform zeta potential value on the formation of the vortex in the microchannel was studied by COMSOL software.The results show that:when the ratio of the treatment area to the non-treatment area is larger than 3:1,the microchannel electroosmotic flow will be in the vortex state.In this paper,the numerical simulation results were verified by measuring the elelctrokinetic velocity of tracing particles.The results show that the fluid in the micro channel which was modified by the polybrene(PB)solution can form vortices in the electric field.(3)A hybrid microfluidic chip based on non-uniform zeta potential was designed and the mixing efficiency was studied under different conditions.The results show that the microchannel with non-uniform zeta potential distribution can make the fluid mixing quickly in the mixing area;when the mixing zone length increases,the mixing efficiency of fluid is enhanced;when the length of the two sides of the mixing area wall are asymmetric,the mixing effect is enhanced with the increase of the asymmetry of the wall area.In this paper,a new method that can enhance the fluid mixing in microfluidic chips is reported,which is of great value to improve the reliability of microfluidic chip devices and to extend the application of microfluidic chips.