Numerical Simulation Study Of Cell Sorting In Microfluidics

Cells are the basic unit of life,and the information they contain can be used for the detection and prognosis of various diseases.Cell analysis is of great significance in clinical applications and biological research.Screening and separating cell populations from heterogeneous biological samples is a crucial task in biomedicine.Compared with traditional cell sorting methods,microfluidic cell sorting has the characteristics of fewer samples,fast response,and high sorting efficiency.At the same time,the microfluidic chip device is very suitable for parallelization,so that a complete lab-on-chip device can perform cell separation,analysis,and experimental processing.Therefore,the use of a microfluidic chip technology platform to sort cells and particles has become one of the research hotspots in recent years and has important practical significance and use-value.This thesis aims at this research hotspot,starting with deterministic lateral displacement sorting technology,hydrophoresis technology,dielectrophoresis sorting technology,and surface acoustic wave sorting technology,using numerical simulation and theoretical analysis methods to analyze the influence of various parameters on cell separation efficiency.The aim is to design a microfluidic chip with high sorting efficiency.The main research contents are as follows:(1)A microfluidic cell sorting model based on the principle of determining lateral displacement was established.The morphology of a new type of inverted heart-shaped micro-pillars with a smaller critical particle size was studied,and the corresponding micro-pillar array was designed for the purpose of separating white blood cells and red blood cells.Through the trajectory of cells of different sizes in the array,the critical diameter is determined,and the influence of the flow velocity on the trajectory of the cell is discussed.(2)A microfluidic cell sorting model based on the principle of dielectrophoresis sorting was established.Dielectric properties are used to separate blood cells based on size,and the influence on cell sorting is discussed from the aspects of microchannel structure and fluid properties.The parameters of the model were determined by comparing the effect of cell sorting in microchannels with different electrode shapes,electrode voltages,and exit angles.By comparing the influence of the conductivity of different fluid media and the relative permittivity of the fluid media on the dielectrophoresis force of the cells,the voltage frequency,and the value range of each parameter that can be used for blood cell separation are determined.(3)Two microfluidic cell sorting models based on the principle of surface acoustic wave sorting were established.The first is to achieve cell separation by setting two sections with different sound pressure intensities in the microchannel.The parameters of the model were determined by comparing the acoustic pressure response in the fluid domain of different piezoelectric substrate materials,the number of interdigital transducer electrode pairs,and the electrode voltage.The second is to use three different modes of acoustic standing waves in the microchannel at the same time to achieve cell separation.The parameters of the model are determined by analyzing the propagation and distribution of sound waves in the fluid domain.(4)A model of dielectrophoresis-assisted hydrophoresis microfluidic cell sorting based on the principle of mixed sorting was established.The parameters of the model were determined by comparing the effect of cell sorting in the microchannel with different microchannel widths,fluid velocity,and electrode voltage.In general,this paper,by studying the mechanism of microfluidic cell sorting,reveals the force law of cells at the micro-scale and establishes a corresponding model for the sorting of blood cells.The research results have certain guiding values for the design and development of microfluidic sorting chips.