Slippery Core‐Sheath Hydrogel Optical Fiber Built by Catalytically Triggered Interface Radical Polymerization

Abstract Hydrogel‐based optical waveguides have attracted extensive attention in optogenetics, implantable photomedicine, and biosensors due to their excellent biocompatibility and tissue‐like modulus in compared with traditional SiO₂‐based rigid optical fibers. However, the existing ion‐induced supramolecular assembly of alginate‐based hydrogel optical fibers commonly lack of long‐term stability due to poor mechanical property accompanied with swollen. In this paper, a novel catalytic surface polymerization method is developed based on a redox reaction mechanism to in situ grow robust and slippery cladding layer on a core poly(ethylene glycol) dimethacrylate (PEGDA) hydrogel fiber by using the alternative H‐bonding poly(N ‐acryloyl glycinamide) (PNAGA) hydrogels. The resultant hydrogel optical fiber with core‐cladding heterogeneous structure can achieve the desirable total reflection condition, leading to good light transmission and low light loss. The PNAGA cladding with robust H‐bonding network endows the hydrogel optical fiber with high stability and outstanding lubrication in humid environment. More importantly, the hydrogel optical fiber possesses good tissue‐like mechanical performance together with excellent biocompatibility, which shows the great advantages for biomedical applications in compared with traditional glass optical fibers. This work will broaden implantable hydrogel optical fibers in material design and structure processibility, promoting the use of hydrogel‐based optical fibers in various applications.