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

Abstract

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.