Integration Of Single-celled Capture Dielectrophoresis Separation Research Of Microfluidic Chip

Cells are the basic units of structure and function in living things.Manipulating and analyzing cells at the single cell level with microfluidic chip technology can effectively reveal the influence of cell heterogeneity on the function and state of the body.Studying the pathological characteristics is important for understanding the cellular metabolism,disorder and so on.Cell separation and single cell capture are important methods for studying cells at the single cell level,but the high cost of the current methods limits their application in life sciences and chemical analysis.In this study,the non-invasive and label-free advantages of dielectrophoresis and the low-cost characteristic of hydrodynamic method are combined,based on which a continuous microfluidic DEP separator with integrated single cell traps is designed and fabricated.Cells are separated based on dielectrophoretic forces with different directions or magnitudes,and then are captured at the single cell level through the micro-trapping structures.Experimental tests are conducted to validate the integration of cell separation and single cell capture in a microfluidic chip.The main contents of this study are discribed below:Firstly,the principle of dielectrophoresis and the principle of fluid dynamics were analyzed.Based on the dipole moment formula of particles,the formula of dielectrophoretic force was deduced,and a multi-layered spherical shell model of equivalent cells was established for analyzing the main forces applied on particles in microfluidics.The Re[K(?)] curves of yeast cells,polystyrene beads,THP-1 cells,and OCI cells were simulated using simulation software MATLAB.Based on the theoretical analysis,the microelectrodes and single cell capture structure were designed.The model of microfluidic chip was established using the software AutoCAD and Solidworks,and the distribution of the electric field and flow field inside the chip was simulated using finite element software COMSOL.Then,according to the structure and function of the microfluidic chip,wet etching of ITO and sputtering platinum are used to fabricate the microelectrode,and the silicon wafer is used as a substrate to fabricate SU-mold of the microchannels and trapping structures.Polydimethylsiloxane(PDMS)is then used to replicate the microchannels and capturestructures,and finally oxygen plasma bonding technology was used to to bond the PDMS chip.Finally,a microfluidic chip experimental test platform was built.Yeast cells and polystyrene beads were separated by using the chip with ITO microelectrode,and then two types of human acute myeloid leukemia cells(OCI-AML3 and THP-1)with similar diameters were cultured,labeled with different fluorescence colors,and then continuously separated on the chip with interdigitated platinum microelectrodes.The separated and purified THP-1 cells were captured at the single cell level on the downstream region of the chip.The purity is over 94%,and the single cell capture efficiency is greater than 94%.