A novel strategy to fabricate a sensitive surface-enhanced Raman scattering substrate with light trapping effect

Abstract The development of high-performance substrates is crucial for achieving sensitive trace detection via surface-enhanced Raman spectroscopy (SERS), and simple and feasible preparation methods remain long-standing objectives. In this study, a novel fabrication strategy is proposed using electrical discharge machining (EDM) to create a sensitive SERS substrate featuring a microhole array with a nanostructured inner surface, offering a low-cost and high-efficiency process. The light-trapping behavior of the substrate was investigated by simulating the reflection trajectory of an incident laser within the nanostructured microholes, and its correlation with microhole dimensions was elucidated. Utilizing precision microelectrodes, a microhole array with high consistency in diameter and depth was fabricated and employed as a SERS substrate for trace detection of hazardous substances. Experimental results demonstrate that, given an identical nanostructured surface, microholes with smaller diameters and greater depths yield stronger Raman enhancement, aligning with simulated trends in incident light reflection frequency. The fabricated substrate exhibited high sensitivity and reproducibility, successfully detecting rhodamine 6G at concentrations as low as 10 –11 M, with minimum relative standard deviations of peak intensities of 7.28% and 6.88% at 773 cm –1 and 1360 cm –1 , respectively. In real-world pond water samples, malachite green and melamine were also detected at low concentrations of 10 –8 M and 10 –7 M, confirming the substrate’s strong anti-interference capability. Given the relative ease of generating such nanostructured microhole arrays via EDM, this work provides a promising approach for fabricating sensitive, reproducible and cost-effective SERS substrates.