A robust and multifunctional conductive double-network hydrogel exhibiting self-healing, anti-freezing, antibacterial, and electromagnetic shielding properties for advanced wearable sensors and biofabrication

Conductive double-network (DN) hydrogels are widely used as flexible sensors for human health monitoring and other applications. However, designing multifunctional hydrogels that adapt to diverse environmental conditions remains a challenge. This study introduces a DN hydrogel composed of polyacrylamide (PAM) and carboxymethyl cellulose (CMC), synthesized via a one-pot strategy in a glycerol-water binary solvent. In this system, PAM forms a rigid primary network, while CMC acts as a flexible secondary network through divalent chelation with Ca 2+ and hydrogen bonding with PAM, significantly enhancing mechanical properties. The hydrogel showed high flexibility, tensile strain (>1550 %), strong adhesion to pig skin (18.3 kPa), and fatigue resistance (800 % static tensile strain over 10 consecutive cycles), which is due to the dynamic hydrogen bonding between glycerol with PAM and CMC. The incorporation of glycerol imparts exceptional freeze and drying resistance, maintaining stability across a broad temperature range (−25 °C to 50 °C). Rheological analyses revealed that the incorporation of Laponite nanoclay into hydrogels significantly enhanced viscoelasticity, shear-thinning behavior, and printability, making the precursor highly suitable for extrusion-based 3D bioprinting, which is mainly due to the Laponite incorporation partially reduces covalent crosslinking between monomers due to steric effects, while simultaneously introducing physical crosslinking points that enhance the overall network stability. Notably, the electromagnetic shielding effectiveness of MXene-incorporated hydrogel reaches 46.3 dB (a 56.16 % improvement) at 5 mm thickness. As a result, the hydrogels exhibit excellent conductivity and strain-sensing performance, enabling reliable detection of both subtle muscle contractions and large joint movements, highlighting their potential for next-generation wearable biosensors and human–machine interfaces. Incorporation of low concentrations silver nanowires (0–600 ppm) enhanced the hydrogels' antibacterial activity, with inhibition zones ranging from 0.46 to 0.62 cm for E. coli and 0.60 to 0.79 cm for S. aureus , achieving up to 95 % and 92 % inhibition, respectively, and highlighting their potential for skin-contact wearable biomedical sensors. These properties make the DN hydrogel prepared in this study a promising candidate for wearable devices and smart sensors in extreme environments.