Evaluation of a Flexible Cellulose-MXene Composite Film for Integrated Energy Harvesting and Sensing in Wearable Electronics

The rapid growth of wearable electronics demands multifunctional, lightweight, and sustainable materials capable of simultaneously integrating sensing and energy harvesting. Herein, we report an eco-friendly, ultralight, and multifunctional free-standing cellulose-MXene composite film fabricated via a facile, green, and cost-effective hydrogel-assisted freeze-drying strategy. The incorporation of MXene nanosheets induces the formation of an interconnected porous and layered microstructures, which significantly enhances sensitivity while maintaining mechanical robustness, structural integrity, and tunable dielectric properties. The optimized composite containing 1 wt % MXene (CM 1%) serves as versatile platform for both piezo-capacitive pressure sensing and mechanical energy harvesting. The pressure sensor exhibits a high sensitivity of 1.12 kPa −1, a low detection limit of 1.2 Pa, wide linear sensing range (0−100 kPa), and rapid response/recovery, enabling precise monitoring of human physiological activities. Interestingly, the same device operates as a nanogenerator, delivering an output voltage of ∼3.3 V, a short-circuit current of 5−50 μA, and a peak power density of ∼8 μW cm −2, sufficient to charge commercial capacitors (1−100 μF). Degradation studies reveal dissolution of the composite film in water within 60 days. This work establishes a low-cost, scalable, and sustainable strategy for developing multifunctional, flexible sensors for next-generation self-powered and environmentally benign wearable electronic systems.