Research On The Electrokinetic Manipulation Of Microparticles In Microfluidic Chip

With the development of related science and technology，Microfluidicchips are increasingly applied in various fields. Microparticle （including cell,bacteria） is one of the important analysis objects of microfluidic chip and themanipulation on micropparticles is a significant function of microfluidic.Electrokinetic manipulation is the most widely used and successful method formicrofluidic chip. Compared with traditional methods，electrokinetic manipulationhas unique advantages both in fluid drive and particles manipulation. Previous studyson microfluidic chip mainly focus on processing technology but the internal physicalmechanism did not get enough attention. Against this background, it is necessary tocarry out the researchs of the manipulation on microparticles in microfluidic chip.In this paper, particles close to the electrode in micro-channel and particlesthrough a90degree bend have been investigated. The forces on particles, the motionof particles and the irreversible deposition of microparticles have been deeply studiedby using numerical simulation methods. The results are helpful to the design ofmicrofluidic chip. The main research work are as follows:(1) The theoretical analysis to electroosmotic flow was carried out and theequations which describe the multiphysics coupled field was established.(2) The theoretical analysis to forces on microparticles was carried out and thecomprehensive model which describe the forces on microparticles and the motion ofmicroparticles, the functions of electrophoresis and dielectrophoresis inmicroparticel’s manipulation has been studied separately.(3) The Fluent’s user defined function(UDF) was used to established a Cprogram which describe the electroosmotic flow and microparticle’s forced motion.The numerical simulation was also carried out.(4) The electric field near microelectrode in a straight microchanel was taken asthe study object, the motion of microparticles close to the microelectrode’s electricfield was simulated and the relationship between electrode’s voltage andmicroparticles’s traped efficiency was got by using statistical method. (5) Take the electric field of90degree micro-bend as the study object, themotion of microparticles witch enter into the non-uniform electric field of the bendwas simulated. The study on microparticles’ irreversible deposition was carried outand the relationship between deposition efficiency and Stokes number(St) was foundby using statistical method.