Flexible and reusable nanobowl-based Ag NPs@Ag-PDMS substrate for enhanced SERS detection

Surface-enhanced Raman scattering (SERS) has gained widespread attention as an effective method for trace molecular detection. Herein, a bowl-structured Ag NPs@Ag-PDMS substrate was developed via a multi-step assembly strategy, where silver nanoparticles (Ag NPs) were partially embedded into the bowl-structured surface of a polydimethylsiloxane (PDMS) matrix while additional Ag NPs were incorporated into the interior. This synergistic architecture significantly amplified the local electromagnetic field, as confirmed by experiments and finite element simulations. Using rhodamine 6G (R6G) as a probe and a fiber Raman spectrometer, the optimized substrate enabled detection at 5 nM with an enhancement factor of 1.22 × 10 6 . The substrate also exhibited good signal uniformity with a relative standard deviation of 6.99 % and maintained performance after five rinsing–reuse cycles. Furthermore, it successfully detected thiram residues on apple peels, showing a linear response down to 3 ng/cm 2 . These findings highlight the high sensitivity, reproducibility, and reusability of the substrate, indicating strong potential for real-world SERS applications in food inspection, environmental analysis, and public health screening.