Highly Sensitive Triple-Network Hydrogels Enable Advanced Sensing for Next-Generation E-Skins

In this work, a highly sensitive, flexible, and stable hydrogel is developed for electronic skin with a triple-network structure composed of polyacrylamide monomer (PAAM), poly(vinyl alcohol) (PVA), PEDOT:PSS, and Fe³⁺ coordination bonds. The hydrogel exhibits exceptional mechanical and electrical properties, including high tensile strength (91.2 kPa), extensibility (1210%), conductivity (178.8 S m^-1 at 200% strain), and long-term durability, achieved through the synergistic effects of hydrogen bonding, dynamic Fe³⁺ coordination, and ionic conductivity. The sensor demonstrates precise and proportional resistance responses to various mechanical stimuli, such as bending, stretching, and tapping motions, enabling accurate detection of joint movements, including the fingers, wrist, and elbow. Furthermore, the hydrogel's fast response and low noise allow for reliable differentiation of motion speeds and the successful transmission of Morse code signals. The long-term stability and cyclic durability of the sensor highlight its robustness for real-time applications. These versatile hydrogels offer a promising platform for wearable electronics, gesture recognition, and human-machine interfaces, paving the way for next-generation interactive sensing technologies. Moreover, the preparation method ensures high reproducibility and scalability, making it suitable for large-scale manufacturing.