Enhancing Detection Reproducibility of Surface-Enhanced Raman Scattering by Controlling Analytes under One Laser Spot

Surface-enhanced Raman scattering (SERS), as a sensitive analytical technique, is expected to be used for quantification of trace analytes. At the current stage, high detection reproducibility should be guaranteed for realizing quantification analysis of trace analytes. The main obstacle to achieving high detection reproducibility is the nonuniform distribution of analyte molecules on substrates, particularly, the "coffee-ring" effect introduced by the flow of solute to the pinning of the contact line. Herein, we report a method to tackle this problem by controlling the location of analytes through tuning the wettability of the SERS substrate. With the combination of silver-assisted chemical etching and photolithography, the ordered Si patterns grafted silver nanoparticles with tunable wettability were integrated into a SERS substrate. With this substrate, high detection reproducibility was achieved by confining all the analyte molecules on the area of active plasmonic hot-spots within one laser, and the quantitative analysis was realized with ultrahigh sensitivity. Furthermore, the substrate is applicable for high-throughput detection.