Biaxially Stretchable Rare Earth-Polymer Multicolor Fluorescent Hydrogel for Human Motion Monitoring and Dynamic...

Smart hydrogels are promising candidates for applications such as information security, flexible electronics, and biomedical devices due to their stimulus-responsive properties. However, the poor mechanical properties and limited stimulus responsiveness of hydrogel materials hinder their applications in complex environments. Therefore, developing smart hydrogels with both mechanical adaptability and optical-response capabilities remains a significant challenge. In this study, a lanthanide-coordinated agarose hydrogel (4HBA-PEI-AGA@Ln³⁺) is fabricated via one-pot photopolymerization. The hydrogel demonstrates synergistic reinforcement through hydrogen bonding and coordination interactions, achieving breakthrough performance: a tensile strength of 110 kPa combined with 1530% tensile strain, high conductivity of 4.34 mS cm^-1 and rapid response characteristics (GF = 3.14, response time of 100 ms). These features enable real-time electrical sensing and precise monitoring of complex human movements. The 4HBA-PEI-AGA@Ln³⁺ hydrogel maintains exceptional elasticity and fluorescence stability during biaxial tensile testing (8100% area strain), establishing a mechanical-optical synergistic encryption system that overcomes the limitations of conventional static anti-counterfeiting technologies. This rare-earth-polymer hydrogel with flexible sensing and dynamic encryption functions provides a dual-effect solution for smart wearable devices and information security protection.