Simulation Analysis And Experimental Research Of Digital PCR Droplet Detection Chip

With the development of PCR technology,digital PCR technology has become one of the most sensitive detection methods in the field of liquid biopsy.It has been widely used in the fields of genetic mutation detection,pathogenic microorganism detection,disease diagnosis and other biomedical detection fields,as well as food safety detection and environmental biological detection.The droplet digital PCR,based on the microfluidic chip technology,is utilized to perform a large number of segmentation,amplification and detection of the target sample,which can realize the absolute quantification of the DNA in sample.Therefore,it is of great significance to study the droplet generation,detection principle,design,and processing of microfluidic chips.In this thesis,VOF model and UDF program are used in the FLUENT software to numerically simulate the movement of the droplets in the flow-focused microfluidic detection chip.The effects of physical and structural parameters such as the velocity,viscosity,interfacial tension and contact angle of the two-phase flow on the droplet detection distance and frequency in the flow-focused droplet detection chip are studied.Based on the conclusions of the research,the structure of the fluid-focusing microfluidic chip is optimized and verified through experiments.The simulation results of the influence of physical parameters on the droplet movement show that the droplet spacing increases linearly with the continuous phase inlet velocity;the droplet spacing decreases exponentially with the discrete phase inlet flow velocity;the viscosity,interfacial tension,and contact angle of the two-phase flow have less influence on the droplet spacing.The simulation results of the influence of structure parameters on droplet movement show that the droplet spacing increases linearly with the inlet width of the continuous phase inlet micro-channel,and the growth slope is about 3;the droplet spacing is negatively correlated with the two-phase flow cross-exit micro-channel size;The angle of the two-phase flow channel has a small effect on the droplet spacing and droplet frequency.Finally,based on the studies of physical parameters and structural parameters,orthogonal experiments are designed and the results are comprehensively evaluated through the ideal solution method.The results show that the optimal structural parameters are continuous phase inlet micro-channel width of 70 μm,discrete phase inlet micro-channel width of 100 μm,and the two-phase flow cross outlet micro-channel width of 100 μm.At the same time,the correctness of the structural simulation law is verified through the experimental platform.