Microfluidic Separation Method Study Based On Electroosmotic Induced Pressure Flow

Microfluidics,also known as Lab-on-a-Chip,is a method for precisely manipulating tiny amounts of fluid through microchannels that range in size from tens to hundreds of microns(Lo C).In recent years,the fields of biomedicine,environmental pollution detection,food safety,and material preparation have all benefited greatly from the use of microfluidics.For these applications,microfluidics allows for the separation and classification of microparticles,cells,bacteria,etc.based on various biophysical features,as well as a reduction in the quantity and price of reagents and the possibility of portability.The difficulty in transferring microfluidic devices outside of the lab is due to the fact that the current microfluidic technology is only "miniature" on a microfluidic chip,peripheral support components like detection tools and syringe pumps are bulky or expensive,and the difficult process of preparing microchannels and electrodes.This thesis describes the development of a portable microfluidic platform based on an electroosmotic induced pressure-driven microfluidic chip for the quick separation and characterization of microparticles,cells,and bacteria.Firstly,this thesis combines the method of electroosmotic induced pressure flow drive and the method of dielectrophoretic separation,and controls the flow distribution and particle trajectory inside the microfluidic chip through the electric field,which overcomes the disadvantages of the traditional drive method that requires external heavy support equipment and improves the integrability of the dielectrophoretic microfluidic chip.This thesis optimizes the preparation process of the microfluidic chip by combining the microchannel and the microelectrode,thus simplifying the chip fabrication process and reducing the chip fabrication cost,Finally,a portable microfluidic platform is built by integrating the designed and manufactured microfluidic chip,detection box,peripheral circuits and the upper computer detection software,and the platform detection function is verified using micro/nanoscale fluorescent particles.In addition,the microfluidic chip designed in this thesis successfully separated 10 μm/5μm polystyrene particles,10μm/990 nm polystyrene particles,polystyrene particles/human bone marrow stromal stem cells and E.coli/human bone marrow stromal stem cells with over 90 % separation efficiency.The research in this thesis breaks through the bottleneck of existing microfluidic separation methods,enriches the theory of fluid mechanics at the microscale,and provides a new perspective and idea for the development of portable microfluidic separation equipment.