Sustainable MXene-based wearable sensor reinforced with microcrystalline cellulose for human motion monitoring in subzero environments with integrated machine learning.

Flexible sensors encounter significant challenges in subzero temperatures, including mechanical fragility, signal instability, and environmental sustainability issues. To overcome these limitations, a novel eco-friendly hydrogel sensor has been developed by integrating guar gum, glycerol, MXene, and microcrystalline cellulose (MCC) extracted from discarded towels. The incorporation of Ti3C2Tₓ MXene nanosheets enhances sensitivity while maintaining mechanical stability and structural integrity. Glycerol functioned as a primary anti-freezing agent, successfully preventing ice crystallization and maintaining flexibility at subzero temperatures. The hydrogel exhibited excellent tensile strength (269 kPa), stretchability (580 %), electrical conductivity (1.49 mS/cm), exceptional functionality at -56 °C, self-healing, and self-adhesion capability at the optimum concentration. It also demonstrated exceptional cyclic stability (600 cycles), and precise detection of human motion. Moreover, the obtained data was processed by support vector classifier for strain prediction, achieving accuracy of 91 % and 95 % F1 Score. The 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazoliumbromid cytotoxicity test confirmed its compatibility for human umbilical vein endothelial cells with cell viability of 79 %. Degradation analysis in pond water ensured the decomposition within 25 days. This work introduces a novel biodegradable sensor with sustainable approach for developing wearable electronics that can operate in extreme environmental conditions including aerospace and arctic exploration.