| As the core of the microfluidic chip,the micropump plays a role in the transmission and distribution of fluids,and it is widely used in the transportation and synthesis of drugs,micro fluid supply and precise control,etc.Conventional pumping methods are mainly dominated by external pressure pumps or peristaltic pumps,but have the disadvantages of complex structure,high operating voltage and large size and so on.The microfluidic chip based microfluidic chip has the advantages of low working voltage,fast response and easy integration,which provides a more convenient platform for experimental research.However,the application range of different driving mechanisms is different,and the lack of ideal microfluidic pumping method is the bottleneck of the application progress of microfluidic devices.Therefore,this work carry out an experimental study on fluid circulation pumping based on the continuous electrowetting effect of Gallium indium tin liquid metal(Galinstan,68.5%gallium,21.5%indium and 10%tin).And based on this,the application of particle filtration experiments are carried out by combining metal rubber and microfluidic technology.Analysis of the mechanism of fluid pumping and particle filtration,modeling and numerical simulation,designing and fabricating the microchannel chip structure,builting the experimental operating system.Based on this,experimental studies are carried out to realize the circulation pumping of different fluids and the filtration of polystyrene beads.First,we analyze the mechanism of continuous electrowetting of pumped fluids: revealing the formation mechanism of the electric double layer,and deriving the formula for calculating the pressure difference of the continuous electrowetting pumping fluid.The mechanism of particle filtration combined with metal rubber material and dielectrophoretic effect are analyzed: the filtration characteristics of metal rubber materials are explained,the dielectric properties of the particles are studied and the polarization phenomenon is analyzed,the form of dielectrophoretic force received by the dielectric particles is derived.Analyzing the force of the particles under the factors of gravity field and flow field.Secondly,designing the overall structure of the microchannel chip,the key parts are numerically simulated: establishing the 3D simulation model of the fluid pumping area,and simulating the velocity field and flow field distribution in the channel,analyzing the variation of fluid pumping speed under different parameters.The simulation model of particle filtration was established: the velocity field and electric field in particle filter simulation are simulated and analyzed,the particle filtration efficiency under different flow rates is studied.Third,we produce the microchannel chip structure and carry out experimental research: carrying out experimental research on circulating pumping of various fluids,provening the feasibility and advantages of Galinstan liquid metal pumping fluids,analyzing the advantages of fluid pumping,and determining the speed variation law of pumping fluid under different parameters.And we carry out a filtration experiment of polystyrene beads: it proves that the filtration efficiency of particles can be effectively improved by the combination of metal rubber filter and dielectrophoretic effect.And analyzing the effect of flow rate on particle filtration efficiency.Finally,we process the date and get the final experimental results. |
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