Research On Microfluidic Impedence Detection And Sorting Combined With Deformation Of Cells

The detection and sorting of single cells is an important area of research in biology and medicine.In recent years,microfluidic electrical impedance detection techniques have been widely used in single cell detection due to their label-free and high-throughput advantages.Characterising the mechanical properties of cells based on cell deformation and enabling cell detection and sorting is an important research direction in microfluidic electrical impedance detection.However,many current microfluidic impedance detection methods deform cells by mechanical extrusion,which reduces the detection throughput and leads to problems such as channel blockage.In this article,cells are deformed by sheath flow shear and parameters related to the mechanical properties of the cells are obtained by electrical impedance detection,which improves the accuracy of the assay and enables the high purity sorting of Hela cells.This method can be used to characterize the dielectric properties and mechanical properties of cells and to sort cells label-free,and has promisingapplications in the detection and sorting of single cells.The main work of this article includes;(1)Electrical modeling and signal simulation for cell electrical impedance detection.A single-shell model of the cell in the suspension system is established,and then an equivalent circuit model for microfluidic electrical impedance detection is built on this basis,including models under the front-to-side electrode,coplanar electrode and its differential arrangement;a simulation model for impedance detection of the coplanar electrode is established,and finite element simulations of the relationship between changes in the lateral and longitudinal position,size and shape of the particles in the channel and the electrical impedance signal are carried out,laying a foundation for subsequent experiments.Theoretical basis for subsequent experiments.(2)Microfluidic electrical impedance detection with cell deformation.A microfluidic electrical impedance detection system was built using two different cell deformation methods,and after comparing the two,the sheath flow shear method was chosen to deform the cells;the feasibility of the sheath flow shear method was verified by theoretical calculations and experiments;the mechanical properties of the cells were characterised by impedance detection,and different phenotypes and types of cells were distinguished,and the results showed that more than 90.8%of the cells were correctly classified.(3)Cell sorting study combined with cell deformation impedance detection.Based on the impedance detection system,a cell sorting system combined with cell deformation impedance detection was designed and built to achieve active sorting of cells in combination with the piezoelectric sorting module;the effect of piezoelectric sorting on fluid deflection was investigated and suitable sorting voltage parameters were determined;the electrical impedance data were collected and processed in real time and the movement of cells in the channel was analysed to correct the calculation of sorting delay;the piezoelectric sorting platform was built using A piezoelectric sorting platform was constructed to sort Hela cells from a mixture of Hela cells and 15 μm polystyrene spheres with a purity of 97.5%and a throughput of 2.7 Hz.