Al3+-Crosslinked Transparent Ionic Conductive PAA-Lysine Hydrogels Toward Flexible High-Sensitivity Electrochemical Sensors

Flexible hydrogel sensors hold great promise in wearable electronics, smart healthcare, and human–machine interfaces, yet their practical applications are often hindered by poor mechanical robustness, insufficient low-temperature tolerance, lack of self-healing ability, and inferior biocompatibility. Herein, we present a multifunctional ionic hydrogel composed of poly (acrylic acid), L-lysine, and aluminum ions (PAA-Lys-Al3+) for high-performance flexible strain sensors. Benefiting from its supramolecular network structure, the hydrogel exhibits efficient self-healing behavior and favorable antibacterial activity, as well as good biocompatibility. Impressively, the gel maintains stable gel-like properties even at −10 °C, overcoming the typical freezing-induced embrittlement of conventional hydrogels. When assembled into a flexible ionic sensor, the PAA-Lys-Al3+ hydrogel delivers high sensitivity, fast response, and reliable signal output toward various mechanical deformations. This integrated combination of antifreeze-resistant, self-healing, tough, elastic, antibacterial, and biocompatible features makes the hydrogel highly competitive in flexible sensing devices operated under harsh environments and biomedical scenarios.