Natural polymer-based soft actuators: from biomass to bioapplications

Nature-inspired soft actuators constructed from polymers have been widely used in wearables, implants, and soft robotics. Despite remarkable progress, conventional soft actuators formed by synthetic polymers exhibit poor sustainability and biosafety, which limit their bioapplications. Recently, natural polymer-based soft actuators have been emerging and opening new avenues for some specific bioapplications thanks to intrinsic renewability, cost-efficiency, biocompatibility, and degradability of natural polymers sourced from biomass. This paper summarizes the state-of-art progress of natural polymer-based soft actuators, introduces the general design principles, discusses how the structure and property of natural polymers affect the actuating performances of soft actuators, highlights their emerging bioapplications in both non-invasive and invasive areas, and offers perspectives on the next-generation soft actuators with enhanced intelligence for broad bioapplications.