A review of the structural design of bionic soft robots based on flexible materials

Abstract Soft robotics is an emerging research field that aims to bridge the performance gap between artificial and biological machines through the use of flexible materials and innovative structural designs. Inspired by numerous examples in nature where biological systems outperform mechanical ones, researchers have drawn from biological principles and integrated them with bionic design concepts. Soft robots leverage the inherent compliance of biological systems, enabling them to safely and efficiently perform tasks in complex and dynamic environments. In recent years, the development of flexible materials with properties closely resembling those of living tissues has significantly advanced the field of bionic soft robotics. This review summarizes recent progress in biologically inspired flexible materials, including elastomers, liquid crystal elastomers, liquid metals, kirigami-based metamaterials, dielectric elastomers, ionic polymer–metal composites, and hydrogels. It explores their superior biocompatibility, compatible actuation strategies, and performance enhancement methods, as well as the structural designs, working mechanisms, and fabrication techniques of various bionic soft robots. These include soft crawling robots, soft manipulation robots, soft underwater robots, and soft amphibious robots. Finally, the ongoing challenges and potential solutions for the application of bionic soft robots in real-world scenarios are discussed, along with prospects for the development of next-generation systems.