Cell Size Sorting System Based On Microfluidics

Cell sorting was regarded as a basic way for single-cell research,which has important value in life science and clinical medical research.Compared with the traditional flow cytometry sorting method,cell sorting which was based on microfluidic technology has a lot of advantages,such as low cost,fast speed,free combination of multi-functional modules,and so on.It has become a research focus in the field of cell sorting.Cell size is the most basic physical property of cells.The occurrence of many diseases is related to cell size.At the same time,the basic way for Cell classification is dependent on cell size.Therefore,microfluidic technology based on cell size for cell sorting has attracted much attention.At present,cell sorting methods by using flow cytometry are difficult to carry out cell sorting according to cell size.Label-free,high-throughput is very necessary for cell sorting which is based on microfluidic chips.Some studies have used previous micro-fluidic structures such as Dean flow,lateral flow,and filters for cell size sorting.Although the throughput is high,purity doesn't arrive at higher purity.This project according to different size cells generates different current pulses which are used to judge the size of size,which was based on the FPGA platform to make judgments and perform sorting.In this way,it can guarantee a high purity sorting the result of 90.6% while the throughput arrived at 50 cells per second.The study of this project provides a new method for sorting based on cell size.This project contents of this topic are as follows:First,the microfluidic chip which is used for sorting is designed according to the cells of different sizes generated different falling particle current pulses in the contracted measurement channel.Different falling current pulses as the basis for judging target cells.The finite element simulation software COMSOL is used to carry out simulation analysis on the designed device structure to verify the rationality of the device design.The optimized device structure is drawn into a layout according to the simulation results and the layout is printed on a silicon substrate coated with SU-8 photoresist through soft photolithography,which is used to form a positive film for making a microfluidic chip.Polydimethylsiloxane(PDMS)is used to make microfluidic chips.Second,finishing the building of the experimental platform.The system includes FPGA circuits for signal acquisition,processing,and control,a microfluidic chip for single-cell analysis,a microscope for cell observation,a protection system for noise shielding,and processing software.This system can complete cell sorting and its velocity of about 50 cells per second.Finally,the feasibility of the experimental platform was verified by using changes in the fluid trajectory in the microfluidic chip and sorting single-size polystyrene fluorescent microspheres.This experimental platform was used to sort a mixed sample which includes 10 microns red fluorescent microspheres and 8 microns green fluorescent microspheres.The average accuracy of the sample collected by the sorting channel was 87.1%.Another mixed sample which includes SW620 cells(diameter about 18 microns)and 8 microns green fluorescent microspheres was sorted,the average accuracy of the cells collected from the sorting channel was 90.6%.This project provides a new high-throughput,high-purity cell size sorting method that can be used in clinical practice such as circulating tumor cells and nucleated red blood cells.