Multi-functional zwitterionic glycerylphosphorylcholine hydrogel for human motion detection and human-machine...

Zwitterionic hydrogels have emerged as promising candidates for next-generation epidermal sensors owing to their inherent biocompatibility, ionic conductivity, and environmental responsiveness. However, achieving a single system that simultaneously integrates good anti-freezing capability, high ionic conductivity, and autonomous self-healing ability remains a big challenge. Here, we report a glycerylphosphorylcholine (GPC)-based, multifunctional zwitterionic hydrogel reinforced with cellulose nanofibers (CNFs) featuring a honeycomb-like hierarchically porous structure. GPC endows the hydrogel with good anti-freezing capability by retaining non-freezable water, while enabling rapid ion transport through ion-dipole interactions. CNFs serve as a mechanically robust scaffold and facilitate good stretchability and resilience. The resulting hydrogel exhibits an exceptional stretchability of 5540 % and a high ionic conductivity of 19.7 S m^-1. Moreover, the presence of multiple reversible physical crosslinks imparts strong interfacial adhesion and rapid self-healing. When integrated into wearable electronics as self-adhering strain sensors, the hydrogel enables reliable human motion detection, real-time electrophysiological signal monitoring, and robotic control through human-machine interfaces, even in subzero environments. Additionally, the hydrogel demonstrates inherent antibacterial activity, further expanding its potential in bio-interfacing applications. This work presents a versatile design strategy for engineering next-generation zwitterionic hydrogels toward multifunctional, low-temperature-tolerant, and self-healing wearable systems.