Study On Microparticle Separation Technology Based On AC Dielectrophoresis

Separation and purification of microparticles are of great significance in many fields,such as medical diagnosis,biochemical analysis and water quality monitoring.Microfluidic chip based on dielectrophorescence technology has become an important method of controlling and separating microparticles due to its advantages such as low loss,easy integration,low cost and rapid separation.In this paper,the separation technique of microparticles based on dielectrophoresis was studied,and the dielectric properties of the microparticles were used for separation.In this paper,microalgae cells were used as the separation target,which laid the foundation for detailed analysis of subsequent microalgae cells.In this paper,a microfluidic chip based on AC dielectrophoresis was designed for the separation of microalgae cells.Firstly,the dielectrophoretic force formula was deduced according to dipole moment in non-uniform electric field,and the frequency response characteristics of microparticles were analyzed by the dielectrophoretic force formula,which laid a theoretical foundation for subsequent separation experiments.Secondly,the flow field,electric field and electric field intensity gradient in the chip were simulated by COMSOL Multiphysics software.By analyzing the electric field strength gradient on the shape of the electrode,the height of the electrode and the width of the main channel,the chip's structure was optimized to improve the separation efficiency.Then,for the experiment of microparticle separation,a chip is fabricated by the photolithography process,including an ITO conductive glass substrate layer,a 3D microelectrode layer,and a PDMS channel layer.Finally,the separation system was used to measure the frequency response characteristics of Platymonas cells,Closterium cells and Polystyrene microparticles,analyzing the effect of frequency for the separation of microparticles.Experiments of separationwere performed by adjusting voltage and flow rate,and the separation effects of voltage and flow rate were analyzed.In this paper,three kinds of microparticles were separated by the separation system,and the separation efficiency was calculated.The separation efficiency of the three kinds of microparticles is above 90%,which verifies that the chip has better separation performance.