Flexible and Highly Sensitive Sandwich-Structured PDMS with Silver Nanowires and Laser-Induced Graphene for Rapid Residue Detection

Flexible surface-enhanced Raman scattering (SERS) substrates offer advantages over traditional rigid substrates for efficient extraction of target molecules from complex surfaces, which is critical for technical applications ranging from pesticide residue analysis to environmental pollutant monitoring and forensic science detection. Herein, flexible sandwich-structured silver nanowires with laser-induced graphene and polydimethylsiloxane (PDMS) (Ag NWs@LIG@PDMS) with high SERS activity, flexibility, and stability were prepared by a simple method. Its detection limit is as high as 10–14 M, which is significantly higher than that of silver nanowires embedded in PDMS (Ag NWs/PDMS) and silver nanowire adhesive PDMS (Ag NWs@PDMS) with bilayer structure, due to the efficacy of interlayer laser-induced graphene (LIG). Moreover, compared with similar structures, the sophisticated structural design of silver nanowires with laser-induced graphene embedded in PDMS (Ag NWs/LIG@PDMS) enables higher SERS activity. Apart from this, the Ag NWs@LIG@PDMS film maintains excellent SERS performance even under 10% tensile deformation and extreme operating temperature (−80 to 80 °C). In view of the above-mentioned advantages, SERS substrates have been successfully used for fast, efficient, low-cost, and nondestructive extraction and detection of peel surface and fingerprint residues in real scenes, providing avenues for molecular trace extraction and detection in food safety and forensics science.