MXene/cellulose conductive hydrogel with stretchability, anti-swelling, antibacteriality and environmental adaptability for wearable flexible strain sensors in human behavior monitoring

The advancement of wearable flexible strain sensors has attracted considerable attention, given their potential to transformative impact human behavior monitoring and enhance human-computer interaction. This study synthesized from carboxymethyl cellulose (CMC) grafted with poly(acrylic acid-co-vinyl imidazole) P(AA-co-VI) and MXene nanosheets, to obtain a multifunctional hydrogel termed C-PAV/MXene. The hydrogel combines the exceptional ductility of CMC with a robust, crosslinked architecture formed by acrylic acid-derived dynamic hydrogen bonds, which enhances mechanical resilience while minimizing volumetric expansion. The inclusion of MXene nanosheets further providing superior electrical conductivity, efficient near-infrared (NIR)-driven photothermal conversion, and inherent antibacterial properties. The synthesized conductive hydrogels demonstrate impressive tensile properties, with an elongation of 964 %, and exhibit high linearity across the entire strain range (R² = 0.98). This hydrogel achieves antibacterial efficacy through a dual mechanism that combines quaternary ammonium groups with the physical bactericidal action of MXene. Furthermore, it effectively converts physical signals generated by human motion into corresponding electrical changes, maintaining efficacy even during motion monitoring in aquatic environments. Moreover, it facilitates the transmission of information through Morse code via variations in pressure and strain. This multifunctional hydrogel demonstrates transformative potential for next-generation wearable electronics by addressing critical limitations in strain/pressure sensing applications.