Functional Hydrogel Coatings for Medical Devices: Recent Developments and Biomedical Applications

Surface coating modification of medical devices is an effective strategy to overcome interfacial incompatibility and associated biological complications encountered in clinical applications. Among various coating materials, functional hydrogel coatings can impart soft elasticity, lubricity, biocompatibility, and anti-biofouling characteristics to underlying medical device substrates while largely preserving their intrinsic mechanical integrity. Unlike existing review frameworks, this review adopts a medical device-oriented framework for functional hydrogel coatings by linking coating function, fabrication strategy, substrate compatibility, device geometry, and clinical application scenario. First, the major functions of hydrogel coatings are systematically summarized, together with the biological and physicochemical mechanisms underlying their interfacial effects. Next, representative fabrication strategies are discussed, with particular emphasis on their applicability to different substrate materials. Subsequently, application-specific design principles are analyzed across representative categories of medical devices, highlighting device-dependent functional requirements, interfacial failure modes, and translational constraints. Finally, current challenges and future perspectives are discussed. This device-centered organization aims to provide a clearer basis for designing next-generation multifunctional hydrogel coatings that are better aligned with practical biomedical applications and clinical translation.