| Molecular diagnosis is an important frontier field in the development of modern medicine.One of its core technologies is nucleic acid detection,which is to detect the existing state or defect of nucleic acid and diagnose human diseases.Microfluidic chip technology utilizes the construction of networked microchannels and supporting control and detection module on the chip to integrate the traditional laboratory into the micron-level operating environment for research.Due to the limitation of equipment,technology and personnel required for nucleic acid detection,it is currently a research hotspot to implement this cumbersome operation process in a microfluidic chip.The research work of this thesis mainly focuses on the design and bonding technology of nucleic acid detection microfluidic chip.Firstly,the chip was designed according to the functional requirements of each operation unit of nucleic acid detection,focusing on the experimental research of the magnetic bead preset in DNA extraction area.By querying the literature,performance analysis and experimental research,etc.,the polymer was selected as the material for chip preparation,including polymethyl methacrylate(PMMA),polydimethylsiloxane,(PDMS)and polycarbonate(PC),etc.Two bonding methods,plasma and adhesive bonding,were used for bonding research.Through experimental research and analysis,the appropriate bonding technology was selected to prepare the designed nucleic acid detection microfluidic chip and the complete the chip.The main research results are as follows:(1)The whole design of the microfluidic chip for nucleic acid detection was completed,including the valve area of the chip,"Y" flow path,"snake" flow path,and "cylinder" detection area.The magnetic bead preset research was carried out,the experimental device and scheme were designed,and the optimal process conditions was determined: selected the modified PVA as the coating magnetic bead material,the reaction concentration is 10%,the reaction time is 8 h,and the reaction temperature is 90 ℃,and the fastest release magnetic beads in 30 s.(2)Plasma bonding mainly studies the influence of the processing time parameters of pmma-pdms composite microfluidic chip on the surface hydrophobicity and bonding effect of PDMS,PMMA and PMMA after silylation.The optimal bonding parameters are obtained by orthogonal test: PDMS,PMMA and silanized PMMA are treated by plasma for 60 s,30 s and 20 s,placement time is 25 s,5 s,5 s,respectively,and the maximum strength is 0.5672 MPa,and there is no leakage phenomenon.The results of this study provide the processing time required for optimal bonding and the effective operating time domain.(3)Four different bonding methods are used in adhesive bonding,including pressure-sensitive adhesive bonding,hot-melt adhesive film bonding,epoxy resin bonding and UV curing adhesive bonding.In this paper,the operation steps and experimental results of the four bonding methods are discussed and analyzed in detail.By comparing the bonding effects of the four bonding methods,the UV curing adhesive bonding is finally selected.The maximum bonding strength of the method can reach 0.2 MPa,and the problems of the other three methods are solved,such as blocking the flow channel,bonding agents or samples,uneven bonding surface,etc.,not only realizes the simple process of chip bonding,but also improves the success of chip bonding,the rate can be applied to the mass production of microfluidic chips. |
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