Cell Separation Microfluidic Chip And Separation Method Research Based On Microstructure Filtration

Cell separation has very important applications in the fields of analytical chemistry and biomedicine.Among the many separation methods,the microfluidic separation method has become a hot research topic because of its fast response speed and low sample demand.The microfluidic cell separation method can be divided into passive separation method and active separation method.Passive separation method has no special requirement for separation cells,and no need for pre-marking,but the chip design is complicated;active separation method has high separation efficiency,but there are special requirements for the cells to be separated,and most of them need to be pre-labeled and treated,which seriously affect cell activity.Combining the advantages of passive separation and active separation,this paper proposed a new cell separation method based on microstructure filteration and dielectrophoresis.This method overcomes the disadvantages in the single separation method and solve the clogging problem which is common in microstructure filtration.By adjusting the geometric parameters of the micropillars structure and the loaded AC signal parameters,the negative dielectrophoresis effect is induced to drive cells to the low field strength region,thereby avoiding cell clogging problems.A 3D model was developed to calculate the distributions of the electric field gradient induced by different shapes of micropillars.The microfluidic chip composed of ITO microelectrode and PDMS microstructure channel was designed and fabricated.Under negative pressure driving,three different sizes particles of 37 ?m,16.3 ?m and 9.7 ?m were successfully separated under the AC signal of 35 Vp~p/10 KHz.The separation and enrichment of Haematococcus pluvialis cells was completed with the AC signal of 100 Vp~p/10 KHz.The effects of electrode spacing and filter tilt angle on the collection efficiency of the chip were investigated,and obtained optimized microfluidic chip structure parameters.Experiment with the optimized chip(electrode spacing of first stage is 500 ?m,filter stage tilting is 60°),the proportion of 37 ?m particles in the collection area was 85%,the collection efficiency of 16.3 ?m particles reached 89%,and the collection efficiency of 9.7 ?m particles reached 90%.This chip also has a good collection effect to Haematococcus pluvialis cells.In the first stage,Haematococcus pluvialis cells with larger size and better activity were collected.and the second stage collected a small amount of Haematococcus pluvialis with large size but poor activity and part of the Bracteacoccus engadinensis cells.The results of this research preliminarily confirmed that the microfluidic chip designed in this paper have good separation and collecting effects on non-biological samples and biological samples,and the separation method partly solved the clogging problem of microstructure filtration method,and improved the separation flux.