SERS detection of glyphosate by Suspended sandwich Ag/SiO2/Ag nanopore array

Surface-enhanced Raman scattering (SERS) is a powerful surface analysis technique that significantly amplifies the Raman scattering signals of molecules adsorbed onto metallic nanostructures, enabling highly sensitive detection of the analytes. The development of low-cost, high-performance SERS substrates through facile and straightforward fabrication methods represents a challenging and highly rewarding endeavor. Here, we develop a suspended sandwich Ag/SiO 2 /Ag nanopore array structure based on template-assisted method with significant plasma coupling effects, which shows an ultra-low detection limit (LOD of 2.91 × 10 −11  mol/L) for 4-MBA molecules, excellent sensitivity (EF = 5.76 × 10 8 ) and high uniformity and stability. COMSOL simulation confirms the electromagnetic coupling in the sandwich structure in addition to the hotspots along the nanopore brims. The proposed SERS substrate enables quantitative detection of glyphosate with the concentration down to 4.66 × 10 −9  mol/L and fulfills the requirements for monitoring pesticide residues.