Fabrication of Au coated sinusoidal grating substrates as SPP-SERS sensor chip for trace-level detection of explosive

The plasmonic metal-coated grating structure has a good candidate for surface-enhanced Raman scattering (SERS) as a trace-level detection sensor in real-world analysis. Herein, a facile approach was explored to fabricate and study SERS performance by gold (Au) sinusoidal grating structure. The sinusoidal grating structure on spinon-glass (SOG) polymer was prepared by thermal nanoimprint technique, then followed by deposited Au film on top via magnetron sputtering technique. This fabrication process was a simple, inexpensive, and high-yield method. The influence of the Au thickness on SERS performance was investigated. The finite element method (FEM) was performed to compare and discuss with experimental studies. From the results, the Au-coated sinusoidal grating SERS chip exhibited good sensitivity for detecting standard Rhodamine 6G (R6G) at 10-5 M. The prepared Au-coated sinusoidal grating SERS chip shows good uniformity and reproducibility. In addition, the practical application for trace-level explosive detection of trinitrotoluene (TNT) solution was demonstrated at 532 and 785 nm excitation wavelengths. Our results show that the Au-coated sinusoidal grating SERS chip exhibits high sensitivity to detect TNT residues with a 10-3 M limit, which could be useful in homeland security applications.