Study On The Technology Of Cell Separation Based On DLD And Dielectrophoresis

Circulating Tumor Cell(CTC)refers to the tumor cells present in the human circulatory system.Most tumor cells will undergo apoptosis or be phagocytosed after entering peripheral blood,but a small number of malignant tumors can spread through the blood to other organs in the body,seriously endanger the health of patients.Therefore,the detection of tumor cells has important research value in medical diagnosis and identification.However,the concentration of tumor cells in the circulatory system is extremely low,with only 1 to 100 CTCs in 109 blood cells,which poses a huge challenge for detection and capture of CTC.Therefore,the rapid and high recovery of CTC from blood is a hot topic in current medical research.Traditional cell separation methods mainly include size filtration,flow cytometry,etc.,but these methods have certain limitations.Micro fluidic technology has become an important means of cell separation with the advantages of high throughput,easy integration,small size and low cost.In view of the above problems,this paper,based on the microfluidic technology and uses the microfluidic chip as the experimental platform to study the efficient separation of tumor cells,mainly including the following three aspects:(1)Cells sorting based on deterministic lateral displacementIn this paper,a passive separation chip for tumor cells based on deterministic lateral displacement was designed.Cell sorting research is mainly based on physical differences such as size and hardness of cells.Firstly,a chip structure based on a triangular micro-pillar array was designed based on the principle of deterministic lateral displacement.Secondly,the velocity field simulation was performed on the separation chip,the critical value of the chip was calculated,and the influence of each parameter in the micro-pillar array on the critical value was analyzed to determine the parameter values of the chip.Finally,the fabrication of a separation chip was completed using soft lithography,and an experimental system was set up to achieve the separation of tumor cells,and the effect of sample velocity and sheath fluid flow rate on the separation effect was studied.(2)Cells sorting based on dielectrophoresis technologyIn this paper,a 3D electrode separation chip for tumor cells based on dielectrophoresis technology is designed,which is mainly used for cell sorting research based on the different dielectric properties between cells.Firstly,deduce the dielectrophoretic force that cells are subjected to in an uneven electric field,and perform frequency response analysis to analyze the separation mechanism between cells.Secondly,the three-layer structure of the dielectrophoretic separation chip was designed,which mainly includes ITO base layer,3D electrode layer and PDMS channel layer.The flow field and electric field simulation on the separated chip were performed,and the influence of chip parameters on electric field intensity was analyzed to determine the chip parameters.Thirdly,according to the designed separation chip,three layers of structure were made respectively by using the photolithography process,and then the manufactured three-layer structure package into a complete chip.Finally,the 3D electrode separation chip was used as the experimental platform to build an experimental system,conduct the separation experiment,and the separation effects of voltage amplitude and flow rate were studied.(3)Multistage cell separation based on deterministic lateral displacement and dielectrophoresisThis paper proposes a multi-stage cell sorting method that combines deterministic lateral displacement technology and dielectrophoresis technology.Firstly,cells of different sizes were separated by a DLD separation chip,that is,the initial screening of mixed samples.Secondly,the sample after preliminary screening is passed into a dielectrophoresis separation chip,and the cells with similar sizes are separated by the dielectrophoresis separation chip according to different dielectric properties,for further screening of mixed samples.This method combines the advantages of DLD and dielectrophoresis technology,which not only increases the separation of cell types but also improves the separation efficiency.