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Soft actuation materials are highly desirable in flexible electronics, soft robotics, etc. However, traditional bilayered actuators usually suffer from poor mechanical properties as well as deteriorated performance reliability. Here, inspired by the delicate architecture of natural bamboo, we present a hierarchical gradient structured soft actuator via mesoscale assembly of micro–nano-scaled two-dimentional MXenes and one-dimentional cellulose nanofibers with molecular-scaled strong hydrogen bonding. The resultant actuator integrates high tensile strength (237.1 MPa), high Young’s modulus (8.5 GPa), superior toughness (10.9 MJ/m3), and direct and fast hygroscopic actuation within a single body, which is difficult to achieve by traditional bilayered actuators. The proof-of-concept prototype robot is demonstrated to emphasize its high mechanical robustness even after bending 100 000 times, kneading, or being trampled by an adult (7 500 000 times heavier than a crawling robot). This bioinspired mesoscale assembly strategy provides an approach for soft materials to the application of next-generation robust robotics.
Cao et al. (Fri,) studied this question.