Magnetically and Mechanically Dual-Oriented Anisotropic Conductive Hydrogels for Directional Flexible Sensing

Conductive hydrogels with soft, stretchable, and tissue-adaptive characteristics hold great promise for flexible wearable electronics, while achieving the synergistic and directional enhancement of both mechanical and electrical properties within a single hydrogel remains a challenge. Motivated by the coexistence of oriented load-bearing frameworks and preferential electrophysiological signaling in plants, we develop a dual-orientation strategy integrating magnetic pre-alignment and mechanical training to construct anisotropic PEI/DMAA-MA hydrogels with dual-aligned polymer networks and conductive pathways. Specifically, Fe3O4@CNC nanoparticles are directionally aligned under an external magnetic field, inducing the preliminary orientation of the PEI/DMAA network through intensive hydrogen-bonding interactions. Subsequent uniaxial cyclic stretching further drives the rearrangement of the OH-CNTs conductive networks along the principal stress direction, promoting the dynamic reconstruction of interfacial interactions. The resulting hydrogel exhibits superior comprehensive performance along the preferred orientation, including excellent mechanical properties (fracture strain of 952.5%, fracture stress of 248 kPa), crack-growth resistance (fracture energy of 357.4 J·m-2), and high electromechanical sensitivity (GF = 1.037). Benefiting from the direction-selective response of the oriented conductive network, the hydrogel sensor enables accurate discrimination of multidirectional human-motion signals and high-fidelity electrocardiogram acquisition. This dual-orientation strategy provides a promising route for developing anisotropic flexible electronics.