Construction Of Microfluidic Chip Based On Two-photon Polymerization Technology And Its Application In Droplet Generation

Microdroplets can provide a precise and controllable environment for biochemical reactions,and have been widely used in modern drug development and cell culture.Compared with the existing droplet generating methods such as microporous membrane emulsification and electrospray,the microfluidic technology has the advantages of good uniformity and high yield.However,ultraviolet lithography,plasma etching,and other technologies commonly used in the construction of microfluidic chips have disadvantages of low processing accuracy,poor size,and structure controllability,which limit the diversity and precision in micron scale of droplet preparation and manipulation.Therefore,this paper proposed a solution to construct the microfluidic chip based on two-photon polymerization laser direct writing technology.The fabricated microfluidic chip has the characteristics of micron scale precision,flat microchannels,and controllable three-dimensional channel structure,which can precisely control the generation and split of droplets.The specific research content includes:Firstly,the construction method for microfluidic chip construction based on twophoton polymerization laser direct writing technology was developed.The corresponding template structures were designed for the three-dimensional microchannels with different scale parameters and geometric shapes,the optimal fabrication parameters including the scanning speed,laser energy,and layer spacing were determined.Combined with the PDMS anti-template,bonding seal,channel modification technology,the microfluidic chips with flat channels,micron scale precision,and controllable three-dimensional microstructures have been constructed.Secondly,the droplet generation chip based on T-channel was designed and constructed.On the one hand,five T-shaped cross structures with different connection angles were designed,and the influence of different connection angles on droplet generation was explored through computational fluid dynamic simulation,after analyzing the frequency and stability of droplet generation,the vertical T-shaped structure was selected to construct the droplet generation chip.On the other hand,computational fluid dynamic simulation and the practical chip were used to analyze the droplet generation mechanism in the T-shaped channel and the influence of fluid velocity,viscosity,surface tension and other parameters on the size and morphology of the generated droplets,and the gel microspheres with good morphology and high uniformity were generated by the chip.Moreover,a passive droplet splitting chip was designed and constructed.Four passive splitting structures were analyzed by computational fluid dynamic simulation,to meet the need for passive splitting of droplets,a symmetric Y-shaped bifurcation structure based on computer simulation and practical splitting chip was studied,three droplet splitting mechanisms and pressure changes during the splitting process were explored,and the uniformity of the splitting droplets was verified by sample representation.Through the above work,this study proved that the microfluidic chip based on the two-photon laser direct writing technology has the ability to generate the droplets with good morphology and high uniformity,and the diversified channel structure and size can accurately regulate the droplet behavior to achieve droplet split.These experimental results are expected to promote the application of laser direct writing technology in the construction of microfluidic chips,and promote the research and development of microfluidic chips in biomedical engineering.