Fabrication Of SERS Active Microfluidic Chip Based On Interface Self Assembly And Its Applications In Pollutant Detection

Surface enhanced Raman scattering（SERS）technology has high sensitivity.It can be used to analyze specific analytes through its unique vibration fingerprint.It has important role and great development potential in surface science,analytical chemistry,food safety,environmental monitoring and biomedical fields.The basic problem in the application of SERS is the preparation of high performance SERS substrate.It is simple and convenient to fabricate SERS substrate by self-assembly.Among them,the two-phase interfacial assembly of metal nanoparticles is simple and rapid,and has a broad prospect.The method of metal nanoparticles assembly on the interface of two phases is simple and rapid,and has a broad prospect.This paper focuses on the following aspects:（1）Silver sol was prepared by two-step method,and spherical silver nanoparticles with good dispersion and uniformity were prepared.Using ethanol as promoter,silver nanoparticles were self-assembled at toluene/water interface and transferred to polydimethylsiloxane（PDMS）to prepare uniform and ordered SERS substrates.The technological conditions of SERS substrate prepared by liquid-liquid film forming were studied,and the possible reasons for the influence of different preparation conditions on the properties of SERS substrate were analyzed.（2）In order to improve the utilization of silver nanoparticles,the scheme of preparing silver film was improved.At the interface of silver glue and toluene,dilute nitric acid was added,and then it was shaken violently for 30 s,and then it was left standing to form metal liquid-like droplets.Rhodamine 6G（R6G）was used as a Raman probe molecule to evaluate the sensitivity,uniformity and repeatability of the SERS substrate.The experimental results show that the substrate has good uniformity（RSD=14.6%）and repeatability（RSD=11.6%）,the detection limit can be as low as 10^-9 M,and it has the ability of dual phase detection.The detection limit of malachite green was 10^-8 M.（3）A microfluidic chip with SERS activity was prepared by mixing silver glue solution and liquid paraffin with dilute nitric acid as traction agent,instead of macro violent oscillation process,silver glue solution and liquid paraffin were mixed in the microfluidic channel to form metal like droplets,which omitted the process of membrane transfer.The sensitivity,uniformity and repeatability of R6G were evaluated.The experimental results show that the substrate has good uniformity（RSD=11.1%）and repeatability（RSD=12.7%）,the detection limit can be as low as 10^-9 M,and it has the ability of two-component detection.The detection limit of methylene blue was 10^-8 M.