Durable, recyclable, and stretchable plasmonic film for grapefruit decay detection.

Flexible surface-enhanced Raman scattering (SERS) sensors show promise for non-destructive, on-site fruit quality monitoring; however, current SERS substrates frequently fail to meet the extended operational stability demands of cross-seasonal agricultural storage systems. This study presents a durable, recyclable, and stretchable plasmonic film (Au@AgNWs/PDMS) for decay detection in grapefruits. By partially embedding silver nanowires (AgNWs) in PDMS and functionalizing surfaces with gold nanoparticles via galvanic replacement, the composite film achieves high sensitivity (10⁻⁹ M rhodamine 6G), mechanical resilience (85% tensile strain tolerance), and long-term stability (49 days). The substrate retains stable SERS performance through 1000 stretching cycles and supports five regeneration cycles without degradation. Practical validation demonstrated its capacity for in situ fungal biomarker tracking on grapefruit surfaces, correlating quinone accumulation with decay progression. Combining conformal adhesion, environmental resistance, and reusability, this technology offers a scalable solution for enhancing food security during storage.