A Facile Method For The Fabrication Of Low-Evaporation Microfluidic Chips And Its Applications

The microfluidic chip,which has the advantages of high throughput,small sample consumption,rapid response and miniaturization,and has been widely used in rapid detection,precision medical and other fields.Polydimethylsiloxane(PDMS)is the most commonly used material for microfluidic chip production,because of its ease of molding,low cost,good optical properties,chemical inertness,and biocompatibility.However,because of the high permeability of PDMS materials,PDMS material-based microfluidic chips are prone to moisture or solvent volatilization during application.Therefore,these chips can not meet the requirements of long-time incubation or elevated temperature reaction,such as protein crystallization,cell culture and Polymerase Chain Reaction(PCR).In order to take into account the advantages of PDMS materials and ensure that microfluidic chips can be applied in low volatility research,this thesis proposes an easyto-manufacture method for glass-PDMS-glass sandwich low-volatile microfluidic chips.The feasibility of the microfluidic chips fabricated by the proposed method was demonstrated by applying them to the protein crystallization experiments,and the antivolatility performance of the chip was initially verified.The main work includes two parts:(1)A simple and convenient method of fabricating a "glass-PDMS-glass" sandwich microfluidic chip based on a caramel sacrificial mold is proposed.The method uses vacuum-assisted microfluidic soft lithography to pattern a sacrificial caramel mold,and combines the embedding and dissolves to ensure the in-situ integration of patterned PDMS film structure in a glass sandwich structure.Without the requirement of demolding and transferring fragile PDMS film,this method is free of tearing,breakage and other problems during fabrication.Furthermore,the microfluidic structure and low volatility of the microfluidic devices fabricated by the proposed method are characterized.The results show that this method can replicate the microstructure of the mold with high fidelity,and the prepared chip exhibits excellent anti-volatility properties,which lays a technical foundation for expanding the application of the PDMS microfluidic chip in the field of low volatility research.(2)In order to verify the practicability of the "glass-PDMS-glass" sandwich microfluidic chip,this method is further applied to fabricate a gradient vapor-diffusion chip for protein crystallization screening.Furthermore,the gradient vapor-diffusion capability was characterized by the analysis of droplet volume change in the microcavity.Finally,the gradient vapor-diffusion capability was further tested by protein crystallization experiments.This gradient vapor-diffusion chip provides an effective tool for screening protein crystallization conditions based on vapor-diffusion mode.