Dynamic Analysis Of Electroosmotic And Pressure Flow On Microfluidic Chip

As the increase of the microfluidic chip's function and the decrease of its size, the flow state and characteristics in microfluidic chip have become more and more complex. At present, simulation and experiment have been the main ways of studying the microfluidic chip. Microfluidic chips are needed to build model in simulation course, then dynamic equation and boundary conditions are added to calculate the dynamics characteristics. The flow condition can be observed in experiment, and then the experimental phenomenon is compared with the results of simulation to optimize the design and facture of microfluidic chips.In this paper, the facture process of microfluidic chips based on PMMA and PDMS polymer and the building of Micro-PIV system were introduced. The PMMA template was made by hot-embossing template. The hot pressing temperature was 120℃, with 6MPa pressure kept in 10 minutes. PDMS chips were moulded with PMMA two-time-template. During the process of moulding PDMS, the temperature was kept at 65℃for 50 minutes. The Rhodamine B was selected as the trace particles in Micro-PIV system. The system includes the microscope, filter, light, CCD, image collection card and the computer etc.The experiment and the simulation were used to study the adjustable orifice channels. The pressure flow form and the characteristics of the orifice flow were simulated in the simulation process. Then the effects to orifice flow velocity brought by the inlet velocity and thickness of the wall were analyzed; The flow state under laminar flow and turbulent flow state was observed using the Micro-PIV system. The critical Reynolds number of the thin/thick-walled orifice, which were measured at different inlet velocity, are 126 and 97.2, respectively.For the research of the cross-structure channel, the formation and the influence factors of the pressure-electroosmotic flow in cross regional were mainly studied in simulation process. According to the conditions of simulation, the phenomenon of the pressure-electroosmotic flow was observed and compared with the simulation results. It is found that electric field has a great effect on pressure-electroosmotic flow in cross regional, which provides guide for entrance and separation process of cross-structure channel.