Micellar Copolymerization Toughened MXene Hybrid PHEAA Hydrogel with Antibacterial and Antifouling Performances for Flexible Sensing

Highly conductive and mechanical hydrogels with antibacterial and antifouling properties are very important for flexible sensors. In this study, a conductive and mechanically reinforced poly(N-(2-hydroxyethyl)acrylamide) (PHEAA) hybrid double-network hydrogel (denoted as PHCKM) was developed through the aqueous copolymerization of HEAA with polymerizable modified MXene and a hydrophobic mixture of stearyl methacrylate, sodium dodecyl sulfate, and sodium chloride (C18-SDS/NaCl) in the micellar form, in the presence of poly(vinyl alcohol). The optimized PHCKM hydrogel exhibited outstanding comprehensive performances, including high tensile strength (720 kPa), large fracture elongation (1000%), excellent moisture retention (>95% after 7 days at 25 °C and 60% RH), good conductivity (0.78 S/m), high antibacterial efficacy (>99%), effective antifouling ability, and strain responsiveness. The hydrogel-based strain sensor can be used for human electrocardiographic and joint motion monitoring. As a proof of concept, a wearable multichannel sensor was explored for real-time hand motion tracking. Benefiting from a machine learning-assisted multiscale signal decoupling model, high-accuracy recognition of 10 different gestures with over 99% accuracy was achieved. Moreover, the hydrogel-based triboelectric nanogenerator (TENG) showed an open-circuit voltage of 140 V, a short-circuit current of 3.5 μA, and a short-circuit transferred charge of 51 nC. Such a TENG can not only effectively harvest mechanical energy, enabling it to power microelectronic devices for up to 22 s, but also realize self-powered human motion sensing, and a conceptual application of real-time handwriting recognition is demonstrated. The promising potential of such a hydrogel sensor for multifunctional human–machine interfaces with intelligent sensing capabilities is foreseen.