Recent progress in fabrications and applications of functional hydrogel films

Abstract Hydrogels are a class of soft and wet materials that typically consist of a three‐dimensional polymer network that swells yet does not dissolve in water. There are extensive research and development of hydrogel materials for diverse applications over the past two decades. More recently, hydrogel films with controlled thickness have been fabricated based on crosslinked natural or synthetic polymer networks. These films not only show the chemical/physical properties of bulk gels, such as biocompatibility and stimuli responsiveness, but also exhibit faster response speed and high flexibility/adaptivity, allowing for new functions and applications. In this minireview, we summarize the recent advances in hydrogel films with focuses on two aspects: (i) methods for facile fabrication of hydrogel films, and (ii) versatile applications of hydrogel films in biomedical and emerging fields. Hydrogel films with controllable thickness, fast response, good compliance, and tunable mechanical properties are ideal materials as artificial muscles and wound dressing, and to construct soft actuators, flexible electronics, and so forth. Current challenges and future perspectives of hydrogel films are also given at the end of this minireview.