Preparation Of Arrayed SERS Substrates And Their Applications

Surface enhanced Raman spectroscopy（SERS）is an efficient surface analysis technique which has been applied in many fields such as biomedicine,sensor devices and environmental pollution,due to their strong Raman enhancement property via the LSPR and the charge transfer effect between metals and probe molecules.At present,many materials including semiconductors,noble metals and transition metals have been developed as SERS substrates because of their high sensitivity,reproducibility,biocompatibility and practicality.It is worth noting that the array of SERS substrates have attracted broad attention due to its superior property for the practice application.Therefore,the chief aim of this paper is to prepare the highly ordered SERS substrate with excellent Raman enhancement property.The main contents are as follows:1.The highly ordered arrays have been fabricated by two methods:First,a layer of epoxy resin was embossed and UV-cured to obtain a highly ordered cylindrical array by NIL,and the morphology of cylindrical array was characterized by 3D laser microscopy and SEM.The results show that the period of the arrays is about 3μm,and the arrays have the morphological features with high fidelity and symmetry.Second,the photoresist was exposed to the 365 nm UV-light against a photomask.After being lithographed,Xenon fluoride gas was adopted to react with bare silicon via etching process,and then the highly stable and conductive silicon arrays were obtained.At last,the noble metal NPs were prepared on these silicon arrays by coelectrodeposition.The period of these arrays is about 10μm,and the diameter of each pillar is about 3μm.2.The noble metal nanoparticles（including Au NPs and Ag NPs）were deposited on the nanoimprint arrays by glow discharge method.The extinction peaks of the metal NPs can be adjusted via changing the sizes and gaps between metal particles.When the extinction peaks of the metal NPs match with the laser wavelength,the samples exhibit the strongest coupling effect,and the SERS characteristics of the noble metal arrays will be optimized.Ag NPs was chosen for the following investigation because of the more significant enhancement effect than that of Au NPs.The effect of thickness of the Ag NPs on the SERS was studied via repeating the above sputtering process for several times.The SERS results show that with the increasing of the thickness of the Ag NPs,the Raman intensity increases and Raman signals are beginning to stabilize totally as the thickness of the Ag NPs grater than 22 nm.These SERS substrates exhibit high EF（enhancement factor）about 0.8×10¹¹and the good reproducibility of Raman signals with the RSD as low as 3.72%.At last,these ordered Ag and Au SERS substrates are used to identify the anthocyanin of wild LR.3.The aluminum-doped zinc oxide（AZO）/Cu-Ag alloy substrates on silicon pillar arrays were prepared by sol-gel and electrochemical co-deposition technique.Due to the interface charge transfer effect exhibited at the interface between AZO and Cu-Ag alloy,the AZO/Cu-Ag alloy substrates effectively enhanced the Raman signal.Finally,these highly ordered SERS substrates were used to detect the glucose with concentrations as low as 10^-6M.Based on the SERS enhancement mechanism,the optimal process parameters of SERS materials with array structures were explored,which would provide a new idea for on-site testing of food safety and drug analysis.