Research Of Droplet Generation Method And Technology In Microfluidic Chip

Droplet generation by microfluidic chip is an important branch of microfluidic research,which developes into a new technology to manipulate tiny volumes of liquid in recent years.As a research focus of microfluidic technology,it has many advantages,such as less sample consumption,quick reaction,good heat and mass transfer effects,and no cross-contamination,etc..Droplet microfluidic technology can be applied to the field of enzyme kinetics,protein crystallization,particle synthesis,drug delivery,Bio PCR technology and detection of the disease and the like.Microfluidic chip is the basis of the technology of droplet generation,so the research and development of microfluidic chip for generating droplet have great significance.Firstly,the research status of microfluidic chip and droplet generation are reviewed,and the type of two-phase flow and influencing factors are expounded,and the basic principles of two-phase flow generated in the droplets are analyzed,including dimensionless parameter,the droplet flow resistance computing and Marangoni effects.It describes the formation mechanism of the droplet of T-type channel,cross-shaped channel and array chips.In addition,the generation process and influencing factors of micro-droplets are studied.Secondly,on the basis of theoretical analysis the writer developed three types of microfluidic chips for droplet generation: one kind of cross-shaped channel microfluidic chip and two kinds of array microfluidic chips.Cross-shaped channel is carried out based on the improvement in the classic,at the intersection of the main channel is set to narrow-mouth,so it is easy to control droplet size and formation rate.It has similar principles of the two array chips for generating droplet,and it takes full advantage of the structure of pits and hollow cylindrical instead of water-in-oil or oil-in-water to generate droplet.Afterwards,the water that is sealed by the structure of the chip and oil turns into the droplet.then it successfully fabricates three kinds of microfluidic chips for droplet generation by photolithography,and they are subjected to surface modification.Finally,droplet generation by three kinds of microfluidic chips is verified by the simulation and experiments.The writer build three chip models by COMSOL software and simulate the process of droplet generation in three kinds of chips.Building experimental platform to conduct experiments with three kinds of chips for droplet generation,and the results of successful generating droplet are the same as simulation results.The experiments analyze the relationship between two-phase velocity with droplet size and the effects of surfactants on the droplet generation in the cross-shaped channel microfluidic chip.Effects of the size of the pits on the droplet generation of the first kind of array microfluidic chip are analyzed through the experiments.At last,effects of hydrophilic surface modification on droplet generation of the two kinds of array microfluidic chips are analyzed through the experiments.The comparison of the experimental analysis and the simulation result is consistent,which verifies the correctness of the theories and simulation research.