Helical ionotropic gel-fiber sensor with omnidirectional strain perception for multidimensional motion correction in adolescent activity assessment

Abstract

Conductive ultra-soft hydrogel-based wearable sensors, despite featuring multifunctional adaptability, still face inherent mechanical weaknesses and inadequate directional stress discernment. To address this challenge, we herein rationally designed a helical twisted alginate/agar/carbon nanotube triple-network composite gel fiber through a low-temperature-assisted wet-spinning technique coupled with cation crosslinking. The resulting gel fibers exhibit exceptional mechanoelectrical synergy, achieving conductivity up to 3.8 S/m while sustaining thousandfold self-weight loads via synergistic polymer entanglement and coordination interactions. The implemented helical architecture demonstrates enhanced strain responsivity (56%-130%, gauge factor), rapid response kinetics (< 0.5 s), and rate-agnostic stability in twisted fibers, enabling 360° spatiotemporal perception through three orthogonally coupled mechanisms: torsion-activated interfacial contact expansion, spiral topology-optimized charge transfer, and stress-dissipative dynamic microcavity formation based on the one-dimensional intrinsic uniaxial deformation amplification of gel fibers under multi-directional stresses. Practical validations include four-phase table tennis swing biomechanics analysis, proof-of-concept for handwriting training and motion correction systems, and motion-encoded encrypted communications, establishing a fundamental mechanistic framework for directional angle sensing with applications in assessment of adolescents’ daily activities. Ultimately, this breakthrough stems from the harmonization of helix-driven anisotropic sensitivity and triple-network viscoelastic dissipation, effectively resolving the longstanding compromise between directional acuity and mechanical durability in hydrogel-based sensors.

Keywords

Conductive hydrogel fiber / triple network / twisted structure / directional spatial awareness / wearable sensor

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