Fabrication of SERS substrates via femtosecond laser reduction of silver nitrate solution: a simple and efficient approach

Surface-enhanced Raman scattering (SERS) technology has been extensively applied in various fields, particularly in trace detection. Nevertheless, the prevailing preparation methods currently suffer from several drawbacks, including intricate preparation procedures, elevated costs, and poor stability. In this work, we center on the fabrication process of SERS substrates via femtosecond laser photoreduction. By capitalizing on the characteristics of high instantaneous power and ultra-short pulse duration of femtosecond lasers, and taking advantage of the property of the weak Raman background spectrum of the polydimethylsiloxane (PDMS) film, a high-density nanostructure with remarkable enhancement performance is formed on the film. Silver nanostructures on PDMS are characterized with scanning electron microscope (SEM). Subsequently, the optimal process parameters are deduced through the analysis of the Raman spectra of samples processed under different conditions. Additionally, the hydrophobic properties, detection stability, and sensitivity of the substrate surface are evaluated. The Raman spectral results demonstrate that the developed SERS substrate exhibits an outstanding enhancement effect, with a detection limit of 10⁻⁸ M for Rhodamine 6G (R6G). Moreover, it possesses excellent stability, with a relative standard deviation of less than 10%. In comparison with conventional methods, this approach eliminates the utilization of toxic chemical reagents and circumvents complex and time-consuming process steps, thereby offering a novel strategy for the rapid fabrication of SERS substrates.