Basic Research On Application Of Microfluidic Dielectrophoresis Chip For Spatial Cell Sorting

In recent years, microfluidic dielectrophoresis(DEP) chip for cell sorting and separation, with its numerous advantages including simple device, easy control, non-invasion to cell and free-label nature, has attracted more and more attentions in the field of clinical medicine, biomedical engineering, cell biology, etc. In the view of the problems that the electric field generated by the traditional planar 2D microelectrodes is quite low in intensity and small in distribution range, and that the process of traditional microelectrode preparation methods is complicated and high-cost, this paper illustrates the design and screen-printing fabrication of microfluidic dielectrophoresis chip with 3D sidewall microelectrodes structure which efficiently and continuously sorts erythrocytes from a mixed suspension with polystyrene microspheres.Firstly, 3D wavy and battlement microelectrodes were designed, and Comsol4.3a multi-physical simulation software was used to explore the influences of microelectrode shape, spacing and thickness on the electric field intensity and distribution, optimizing the structure parameters of the two kinds of microelectrodes. Then, the structures of microchannel matched with different microelectrodes were designed.Secondly, microelectrodes and microchannel, which were fabricated via screen printing technology and lithography method respectively, were sealed by oxygen plasma treatment to obtain the designed microchip. During the process of microchip preparation, factors affecting the printing quality of microelectrodes, such as parameters setting of screen printer, stencil and ink, were explored, and the technological parameters of lithography method were optimized according to the microchannel structure.Thirdly, the dielectric properties of erythrocytes and PS microspheres under different voltage, frequency and solution conductivity were measured by a simplified chip which was made of microelectrodes and polydimethylsiloxane(PDMS) with dug hole. Then, the dielectric spectra of each particles were plotted to provide theoretical basis for continuous sorting procedure. Meanwhile, the hemolysis ratios of erythrocytes under different experimental conditions were measured to evaluate cell viability.Finally, the preliminary experimental conditions, selected based on the dielectric spectra of two kinds of particles and the results of erythrocytes’ hemolysis experiment, were adopted in the dynamic sorting experiments of each type particle, and the influences of solution flow rate, voltage, frequency and solution conductivity on particle’s sorting efficiency were discussed to optimize the conditions where erythrocytes can be continuously sorted from a mixed suspension with polystyrene microspheres with a high sorting efficiency.The results of this paper indicate that it is feasible to use the screen printing method to fabricate the microfluidic DEP chip for the continuous sorting of mammalian cells.