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

Abstract

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.