MXene@GN-based conductive hydrogel with mechanical flexibility and self-adhesion for wearable strain sensors

Conductive hydrogels are endowed with adjustable flexibility, stimulus responsiveness, and multimodal sensing, are widely applied in wearable electronics. However, their performance, particularly in terms of mechanical flexibility, electrical conductivity, and application diversity, remains constrained. Among various strategies, the incorporation of graphene (GN) into hydrogels has emerged as a potential solution due to GN’s remarkable mechanical, electrical, and functional characteristics. However, the inadequate dispersion of GN nanosheets within the hydrogel matrix can compromise the sensitivity and long-term cycling stability of flexible sensors. In this study, we found that untreated GN, after exfoliation with ionic liquids (ILs), can achieve good dispersion within hydrogel. A three-dimensional network hybrid hydrogel (A-2MX-0.2I 16 @G) was successfully prepared by using two types of one-dimensional polymer chains (N, N-methylene bisacrylamide (MBA) and polyacrylic acid (PAA)) together with two types of two-dimensional nanomaterials, Ti 3 C 2 T x (MXene) and GN nanosheets as quadruple crosslinkers. The obtained hydrogel has special properties, including high tensile strength (up to ∼955 % strain), significant toughness (tensile strength ∼200 kPa), and high sensitivity (GF=3.01). It is worth noting that sensors based on A-2MX-0.2I 16 @G hydrogels have higher sensitivity in detecting electrical signals from various human movements. These advantages enable our hydrogels to maintain stability and repeatability under strain, making it promising for multifunctional sensing applications.