Research Of Self-Assembled SERS Based On Microfluidic Chip

This thesis mainly studies the self-assembled Surface Enhanced Raman Scattering(SERS)chip based on microfluidics.SERS technology is a powerful surface detection and analysis tool that can be applied to biomedical sensing,and microfluidic technology can be used to process samples to be tested.The combination of the two techniques makes SERS more widely used.In this thesis,the chemical self-assembly method was used to successfully prepare a SERS substrate with low detection limit,which was combined with a microfluidic chip that can separate blood cells for blood detection of cancer patients.First,based on the Fano resonance mechanism,a gold nanoparticles-dielectric layergold film sandwich structure is proposed for the preparation of SERS substrates.The structure is simulated by finite element simulation.The absorption spectrum and scattering spectrum of the gold nanoparticles-dielectric layer-gold film sandwich structure are obtained,the electromagnetic field distribution diagram,and the generation principle and control mechanism Fano resonance are introduced in detail.The position of the Fano valley is regulated by changing the parameters of the gold nanoparticlesdielectric layer-gold film sandwich structure.When the position of the Fano valley is closest to 785 nm,the intensity of the SERS signal excited by the laser is the strongest.The biggest influence on the Fano resonance effect is the size of the gold nanoparticles and the distance between the gold nanoparticles and the gold film.The optimal size of gold nanoparticles and the optimal sphere-membrane spacing are initially obtained through simulation.Secondly,according to the finite element simulation results,we designed a facile SERS substrate preparation method.By using biotin-streptavidin to link the chemical functional group modification,the gold nanoparticles are assembled on the gold-coated thin film by self-assembly to form a single layer of closely distributed gold nanoparticles.And by controlling the molecular weight of polyethylene glycol to adjust the distance between the gold film and the gold nanoparticles.When the Raman laser is 785 nm,the Raman signal enhancement effect of SERS substrate on 4-aminothiophenol(4-ATP)is very strong.Finally,this thesis designs a microfluidic chip that can separate cells from blood,which can perform high-throughput,rapid,and non-destructive detection and analysis of trace analytes.The PDMS microfluidic channel was fabricated by photolithography and molding method,and the SERS substrate was fixed in the microfluidic channel,which could realize the simultaneous detection of blood and plasma in the same sample.The final experiment shows that the microfluidic SERS chip can be used to separate hemorrhagic cells from blood and detect the plasma obtained after separation,which has a good prospect in IVD(in vitro diagnosis).