Multifunctional Eutectic Hydrogel with Antifreezing and Self-Powered Capabilities for Object Recognition Sensing

Hydrogels have attracted extensive research interest due to their remarkable stretchability and flexibility, enabling their integration into advanced applications such as flexible sensors, triboelectric nanogenerators (TENG), and supercapacitors. However, their high free water content renders them susceptible to freezing at subzero temperatures, leading to a loss of flexibility and severely restricting their performance in cold environments. To address this challenge, a freeze-resistant eutectic hydrogel composed of polyacrylamide (PAM)/deep eutectic solvent (DES)/phytic acid (PA) (PDP) eutectic hydrogel is systematically fabricated by partially replacing the free water in conventional hydrogels with DES. PDP eutectic hydrogel exhibits a combination of excellent properties, including high transparency (93%), exceptional stretchability (up to 1934% strain), and a high gauge factor (GF = 8.20). Importantly, PDP eutectic hydrogel retains excellent flexibility and stable sensing performance under extremely low temperatures. Its high sensitivity enables precise, real-time monitoring of human motions in flexible sensor arrays, which supports the development of a deep learning-integrated system capable of capturing subtle grasping motions and distinguishing between objects of varying shapes. This work offers a novel strategy to address the intrinsic freezing limitations of conventional hydrogels, significantly expanding their potential for use in demanding and low-temperature environments.