Multifunctional double-network Ti3C2Tx MXene composite hydrogels for strain sensors with effective electromagnetic interference and UV shielding properties

The advent of hydrogel-based flexible strain sensors has generated enormous research interest due to their outstanding biocompatibility. However, developing hydrogel-based strain sensors with high gauge factor, wide detection range and multifunctional integration is still challenging. Here, a novel multifunctional hydrogel-based strain sensor is composed of two-dimensional transition metal carbides/nitrides (Ti3C2Tx MXene) and Poly-acrylamide-co-Poly-N-hydroxyethylene acrylamide/Carboxy Methyl Cellulose-Fe3+ dual network structure (PAAm-PHEMAA/CMC-Fe3+) with multiple hydrogen bonds and coordination interactions. The dual network design endowed the hydrogel-based human motion sensor with fast rebound and high tensile properties, enabling it to exhibit high sensitivity (response time-120 ms and gauge factor-1.62), and a wide detection range (0-700%), including joint movements as well as more subtle human motions (facial micro-expression changes and speech). More importantly, the hydrogel-based strain sensor exhibited excellent EMI (41 dB, X -band) and UV shielding properties (365 nm, 100%, 0.5 mm) due to the synergy of porous structure, moderate conductivity, and ionic solution environment. Moreover, it demonstrated robust adhesion (29 kPa), high shape adaptability, and self-healing capability. This innovative multi-functional flexible sensor design provides guid-ance for the development, research and application of high-performance flexible wearable materials.