Self-powered food quality monitoring and shelf-life extension using a multifunctional patterned cellulose nanofiber composite triboelectric nanogenerator.

Smart packaging plays a vital role in preserving fruit quality, reducing microbial spoilage, and mitigating postharvest losses. Real-time monitoring of relative humidity (RH), estimation of fruit storage time, and extension of fruit longevity are essential for delivering high-quality products to consumers. Triboelectric nanogenerators (TENGs) are a promising platform for developing self-powered smart packaging systems without external energy sources. In this work, a biodegradable cellulose nanofiber (CNF) was used as the triboelectric layer because of its biocompatibility. To enhance triboelectric output, the CNF was first composited with titanium dioxide (TiO2), titania nanotubes (TNTs), and titania nanotubes decorated with copper(I) oxide (TNT-Cu2O) at various weight ratios, and then patterned to increase contact area. These nanofillers have higher dielectric constants and electron affinities than pure CNF, improving charge induction efficiency while also providing moisture absorption and antibacterial activity to enhance fruit storage conditions inside the package. The optimized patterned CNF/TNT-Cu2O (10 wt%) TENG produced an open-circuit voltage of 377.4 V, a current of 37.6 μA, and a high power density of 7.8 W·m-2. As a self-powered humidity sensor, it demonstrated a maximum response of 1057% inside a sealed package. Additionally, electrical resistance variation was used to estimate fruit storage time, while antibacterial and moisture-absorbing properties of the film helped delay spoilage. This multifunctional platform offers a sustainable approach to smart food packaging and real-time postharvest monitoring.