Construction And Applications Of Miniaturized Microraman Spectroscopy System

In recent years,with the frequent problems of food safety,medical products and private contraband,the demand for rapid field detection has continued to grow.As a powerful analytical tool,Raman spectroscopy has attracted more and more attention in the fields of medicine,food,environment and materials.Despite the high performance of laser confocal micro Raman spectroscopy system,it is massive for field detection.And portable Raman spectroscopy system has challenges in sensitivity and spatial resolution.On the other hand,surface enhanced Raman scattering（SERS）greatly reduces the limit of detection（LOD）of Raman spectroscopy.Since the performance of SERS substrates directly affects LOD,an excellent and low-cost SERS substrate has been the key to Raman spectroscopy detection and its application.In this paper,the following work is conducted.To achieve the Raman in-situ analysis of microstructures of the samples,Raman imaging of spatial distribution and rapid field detection,a miniaturized micro Raman spectroscopy system is constructed.The system consists of 785nm single-mode laser,microscope,external optical module,confocal module and monochromator.A confocal module was built,and with a microscope objective,the spot size of system was focused to about14mm.The Raman signal collected by external optical path was directly coupled into the slit of the monochromator,reducing the loss from optical fiber coupling and improving luminous flux of system.The system was calibrated and its performance was investigated.with a spectral range of800 nm-1044 nm and a spectral resolution of 4-6 cm^-1,it was demonstrated that the system possessed good wavenumber accuracy,spectral detection sensitivity and stability..In order to test the performance of the constructed Raman spectroscopy system,Raman measurement of laser color printing ink stains were conducted and a preliminary spatial distribution of cyan toner was investigated.In addition,a mixed powder sample was measured by the constructed system using metronidazole tablet as main drug ingredients and tapioca starch as excipients.Combined with Partial Least Squares algorithm,the concentration distribution of sample was predicted,showing its inhomogeneous.A simple method based on roll-to-roll ultraviolet（R2R UV）micro-pyramid imprinting technique and nanoparticle self-assembling process in aqueous solution to fabricate large-area,flexible SERS substrate is proposed.Using Rhodamine 6G（R6G）as probe,it was demonstrated that the substrate could detect a trace R6G low to 10^-9 mol/L and possessed a good uniformity and reproducibility.In addition,the feasibility for rapid detection of dye in herbal tea based on this SERS substrate is investigated.It is presented that the R6G of4′10^-7g/ml,Malachite Green of 10^-6 g/ml and Auramine O of 10^-6 g/ml in herbal tea could be detected rapidly.