Ag/AgCl@agar/P(AM-co-HEAA) hydrogel with ultra-stretchability, fatigue resistance, and freezing tolerance for human motion and electrophysiological signal monitoring

Conductive hydrogels have garnered significant attention for flexible electronics, yet simultaneously achieving optimal mechanical robustness and electrical performance under harsh conditions remains challenging. Herein, an ion/electron dual-mode conductive Ag/AgCl@Agar/P(AM- co -HEAA) hydrogel was developed for wearable motion detection and electrophysiological signal monitoring. The hydrogel exhibited outstanding mechanical properties, including excellent stretchability (2207 %), high tensile stress (0.32 MPa), and remarkable toughness (3.90 MJ/m 3 ). As a strain sensor, it displayed high sensitivity (GF of 4.17 within 1100–1400 % strain), stable and reproducible resistance signal output across both micro-strains (0.01–0.1 %) and macro-strains (200–1400 %), and excellent working durability and reliability (200 cycles at 200 % strain). Notably, it also demonstrated reliable sensing performance even at −20 °C due to the ion/electron hybrid conductive mechanism. These unique properties enabled the hydrogel successfully applied in real-time human motion detection and human-machine interaction. Moreover, the hydrogel semi-dry electrodes displayed low potential drift (4.64 μV/min) and electrode-scalp impedance (13.2 ± 1.6 kΩ at 10 Hz). Significantly, the hydrogel electrodes achieve clinical-grade ECG and EEG signal acquisition, comparable to commercial wet electrodes. These superior properties, combined with facile fabrication, make this multifunctional hydrogel a promising candidate for next-generation wearable devices in motion monitoring and human–machine interactions.