Reusable Ag SERS substrates fabricated by tip-based mechanical lithography

Surface-enhanced Raman spectroscopy (SERS) is a highly sensitive, non-destructive technique that amplifies molecular scattering signals via engineered 'hot spots' at the micro/nanoscale. However, currently SERS substrates still face problems such as disposable use, poor consistency, strict environmental requirements, and complex processing processes. The development of new SERS substrates is crucial for advanced detection. In this study, a reusable and consistent Ag-based SERS substrate was developed with scanning probe lithography (SPL). Based on the designed machining with a diamond tip, the effects of parameters, including normal load, scanning feed/spacing, period and amplitude, on the formation of micro/nanostructures on Ag surface were investigated to meet the best candidate for SERS substrate. This method can be applied to soft metals like Au, Ag, and Cu, with Ag substrates demonstrating a higher Raman detection limit compared to Au or Cu. Finally, the reuse of Ag SERS substrate was achieved by surface cleaning and/or oxide layer removing. This study highlights a low-cost and feasible approach to high-performance SERS substrate preparation, with significant potential for practical applications and further research.