Self-powered chitosan-based nanofibrous intelligent packaging for monitoring of strawberry freshness

Strawberries are susceptible to water loss, microbial spoilage, and quality deterioration during storage and transportation, resulting in a shortened shelf life. Intelligent packaging integrating active preservation and freshness indication can delay deterioration while providing quality feedback. Humidity variations caused by respiration and transpiration are closely associated with strawberry quality deterioration, yet their conversion into real-time data feedback remains challenging for conventional systems. Herein, a self-powered humidity-sensitive chitosan-based nanofibrous packaging material was fabricated via electrospinning. Deacetylated chitin nanocrystals (D-ChNCs) nanoframe reinforcement and tea polyphenols (TP) functionalization synergistically constructed a CTS/PEO/D-ChNCs/TP three-dimensional nanofibrous network. The heterogeneous interfaces and polar functional groups promoted triboelectric charge accumulation, enabling the triboelectric nanogenerator (TENG) based on this membrane to achieve an open-circuit voltage approaching 180 V. Benefiting from the abundant hydrophilic functional groups and large contact area, the TENG converted packaging humidity variations into voltage signals. As the relative humidity (RH) increased from 50% to 80%, the output voltage decreased linearly (R² = 0.993), enabling reliable humidity sensing. The D-ChNCs/TP-functionalized membrane exhibited antioxidant and antibacterial activities, delaying strawberry deterioration for 6 days. Meanwhile, the TENG output signal was strongly correlated with weight loss, firmness, and total soluble solids, enabling self-powered classification of strawberry freshness.