Graphene-based porous hydrogels with a tunable piezoresistive response for wearable strain sensing

This study reports the synthesis of porous hydrogels templated by self-assembled, percolating graphene networks formed through the spontaneous exfoliation of graphite at oil-water interfaces. The resulting graphene-stabilized emulsions yield an open-cell hydrogel architecture that enables efficient stress-dependent modulation of electrical pathways. Compression testing and electrical characterization revealed a pronounced reduction in resistance under strain, producing a robust and reliable piezoresistive response with a gauge factor of approximately 13 at 5% strain. Cyclic compression-relaxation experiments confirmed the high reversibility and stability of both the mechanical and piezoresistive responses. Crosslinking density strongly influenced sensitivity, enabling tunable piezoresistive performance suited for real-time motion monitoring. When mounted on a finger joint, the hydrogel exhibited smooth changes in resistance (35%-70%) as the bend angle increased from 30° to 90°, with excellent signal stability under static deformation. Additionally, the hydrogels demonstrated strong absorptive capabilities, enabling efficient removal of organic dyes and metal ions through repeated compress-release cycles. Collectively, the combination of elasticity, electrical conductivity, and sorption functionality positions these graphene-templated hydrogels as promising candidates for wearable sensing technologies and environmental remediation applications.