Abstract: An ideal flexible sensor should possess excellent mechanical properties, outstanding electrochemical performance, and high environmental tolerance to ensure long-term applicability in wearable electronics. However, integrating these multifunctional properties remains a major challenge. Inspired by human skin tissue, this study develops a poly (acrylic acid)-TA@CNF (PTCCG-Na⁺) hydrogel with a hierarchical network via a hydrogen bond recombination strategy assisted by salting-out. The tannic acid-encapsulated cellulose nanofibers (TA@CNF), containing rigid crystalline regions and abundant hydrogen bonding sites, interact with glycerol and poly (acrylic acid) (PAA) to form a dynamic hydrogen bond network. This structure imparts the hydrogel with remarkable tensile performance (> 1300%), long-term cycling stability (> 2000 cycles), and broad environmental adaptability (-40 to 80 °C). Additionally, NaCl and carbon nanotubes (CNTs) serve as physical reinforcement agents, providing additional physical crosslinking and synergistically enhancing the electrical conductivity (72.88 mS cm^-1) of the hydrogel. These combined features allow the hydrogel to be applied in wearable sensors for heart rate and pulse monitoring, as well as in supercapacitors (capacitance: 422.545 mF cm^-2 at 0.83 mA cm^-2). This study presents a novel strategy for developing hydrogels with stable mechanical properties, exceptional environmental tolerance, and high conductivity.

Key words: Hofmeister effect, Conductive hydrogels, Flexible electronics, Flexible energy storage devices, Sensor