Muscle-inspired MXene-based conductive hydrogel by magnetic induced for flexible multifunctional sensors

In recent years, conductive hydrogel-based flexible electronic sensor devices have gained widespread attention in the fields of flexible wearable devices, human-machine interaction interfaces, medical monitoring, etc. However, conventional conductive hydrogels struggle to concurrently achieve exceptional mechanical properties and high conductivity, often exhibiting isotropic mechanical performance and sensing characteristics. In contrast, biological tissues typically demonstrate anisotropic mechanical properties and sensing capabilities due to their ordered microstructure. Drawing inspiration from the ordered structures of biological tissues, this study proposed a simple strategy to fabricate high-strength anisotropic MXene-based conductive hydrogels. Initially, a magnetic and conductive two-dimensional nanohybrid material (PDA-Fe3O4-MXene) was synthesized via acid etching and PDA-mediated co-precipitation methods. Secondly, a magnetic field-induced orientation strategy was employed to induce the oriented arrangement of PDA-Fe3O4-MXene within a dual-network polyvinyl alcohol/polyacrylamide (PAAm/PVA) hydrogel. Subsequently, the oriented PDA-Fe3O4-MXene structure was fixed in the dual-network hydrogel by the photopolymerization and freezing-thawing methods. The anisotropic conductive hydrogel exhibited a highly oriented structure, conferring its anisotropic mechanical properties and conductivity. Its mechanical and conductive performances were enhanced in an anisotropic manner, demonstrating outstanding tensile strength (156 KPa) and good conductivity (1.10 mS/cm). Moreover, the conductive hydrogel-based sensors showcased a broad working range (3 %–300 %), rapid response time (290 ms), high sensitivity, and exceptional stability. This work presents a novel approach for constructing flexible electronic devices based on anisotropic hydrogels, offering promising prospects for various applications.