Research On Maching Method Of Diectric Breakdown Electro-seepage Microfluidic Chip

Microfluidics technology is a new analytical technology developed in recent years.Lab on a chip contains a variety of functional units and microchannel networks to complete the reaction,separation and detection functions.The sample exchange between different units depends on the flow of the liquid,so the microfluidic chip in the fluid movement is of great importance in the microfluidics technology.Electroosmotic flow is an important fluid manipulation technique of in microfluidics.It is directly driven by electric field to drive the fluid without the need for micro-pump and micro-valve structure,it also has the potential for the integration and miniaturize.This research begins with the basic theory of electroosmotic flow formation,the control equations of electric field and flow field dual physics field are deduced.The flow of two-dimensional uniform micro-channel electroosmotic flow and dielectric breakdown electro-seepage flow is studied.The microfluidic chip with dielectric breakdown is fabricated by two kinds of processing methods.The microfluidic chip was fabricated by comparative analysis and cost-effective processing.The electrodeposition velocity was measured by current monitoring method.(1)Simulation analysis of electroosmotic flow in micro fluidic chip.The two-dimensional straight micro-channel model is established,and the corresponding fluid parameters and boundary conditions were set.The voltage was applied only between the centre sections,causing the electroosmotic flow to make the pressure difference between the left and right sides of the two-dimensional flow channel,To mark the distribution of the velocity field in order to achieve the purpose of speed field visualization.(2)Research and simulation design of dielectric breakdown electro-seepage driving.A similar type of double-T model was established,with a thickness of 5 ?m in the middle of the dam.By adjusting the voltage across the microchannel,and the breakdown of the 5 ?m dam is achieved with the voltage of 70 V.Then,the potential change of the dam is analyzed in details,and the law of fluid movement in the whole microchannel is analyzed.(3)Dielectric breadown of electroosmotic flow in microfluidic chip.Two fabrication approachs were carried out,the first one is the SU-8 pattern transfer from PDMS,and the second one is the SU-8 pattern transfer from dry film-for the dielectric breakdown of electroosmotic flow in microfluidic chip.The microfluidic chip with a breakdown dam was obtained with these two experiments.And these the two kinds of fabrication methods were compared and analysised in details.(4)Microfluidic chip sample inlet and dielectric breakdown experiments.Use a dual-channel syringe pump to pump the sample into the microchannel.And then analysis for the possible causes of leakage on the production of microfluidic chip process has been improved.Through the improvement of the microfluidic chip fabrication approach,no leakage was observed during the sample inlet process.The breakdown test was conduted with two microfluidic chips,result in a stable voltage,indicating the occurrence of dielectric breakdown.(5)Electroosmotic flow velocity detection.The results show that the EOF velocity decreases with the increase of the concentration of NaCl,but there is no linear decreasing relationship between the concentration and flow velocity.The results show that the EOF velocity decreases with the increase of the concentration.