Self-healing, tough hydrogels with long-lasting moisture and extreme temperature tolerance and application for flexible sensors

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• The hydrogel flexible sensor was successfully realized by functional rGO. • rGOs@PPy-hydrogels have a good self-healing ability, excellent conductivity, and long-lasting moisture lock-in capability. • rGOs@PPy-hydrogels have a high tolerance for extreme temperature. • Sensors based on rGOs@PPy-hydrogels exhibited an excellent detection ability of motion. Self-healing hydrogels hold extensive potential applications in the realm of flexible wearable devices. Herein, graphene oxides (GOs) were concurrently reduced and functionalized via the Ritter reaction, followed by the oxidative polymerization of pyrrole on the surface of the reduced graphene oxides (rGOs), thereby yielding a functional nanocomposite (rGOs@PPy). This rGOs@PPy exhibits outstanding electrochemical properties, ensuring the electroconductibility of hydrogels, which can subsequently be employed in the development of flexible sensors. The rGOs@PPy-hydrogels exhibit excellent mechanical properties (strain up to 1000%), and remarkable self-healing capability, approximately 85%, attributed to the reversible noncovalent bonding interactions. Furthermore, these hydrogels possess several notable advantages, including high sensitivity with a response time of approximately 191 ms, and a broad operating temperature span of −20 to 45 °C. Significantly, the composite hydrogels can be utilized to construct wearable strain sensors capable of monitoring joint movements as well as subtle pulses. These sensors generate corresponding signals for various motions, with the signals remaining nearly stable after multiple cycles of movement. Owing to the excellent sensitivity, high recognition capability, and relative stability, these flexible sensors hold promising application prospects.