Self-assembly of Ag NWs on the surface of modified grating PDMS film for flexible SERS sensors

Flexible Raman-enhanced substrates possess the advantages of good adsorbability and extensibility, which are particularly beneficial for the effective analyses of target molecules on complex or irregular surfaces. Here, we reported a large-scale, flexible and transparent surface-enhanced Raman scattering (SERS) substrate. This Ag NWs/M-CDG/PDMS substrate was composed of a modified compact disc grating polydimethylsiloxane (M-CDG/PDMS) film decorated with silver nanowires (Ag NWs) through a self-assembly process. The surface of the grating PDMS film was modified with 3-aminopropyltriethoxysilane (APTES) to create a hydrophilic layer. The contact angle of the APTES-modified PDMS film decreased from 105° to 66°, indicating improved hydrophilicity compared to the unmodified film. Thiram was chosen as a probe molecule to evaluate the SERS performance of the prepared substrates. It was found that the substrate displayed high SERS sensitivity with a detection limit for thiram as low as 10^− 8 M, and good uniformity, evidenced by RSD (relative standard deviation) values of 8.7% and 9.9%. Moreover, the fabricated substrate showed good mechanical stability and SERS enhancement effects even under backlight illumination, making it suitable for in-situ SERS detection on curved surfaces. The Ag NWs/M-CDG/PDMS flexible substrate also demonstrated the advantages of anti-corrosion, mixed detection capabilities, a wide operating temperature range, and the ability to perform vapor phase detection. In summary, the developed Ag NWs/M-CDG/PDMS substrate had great potential for practical applications in detection technologies.