Reconfigurable Soft Actuators With Multiple-Stimuli Responses

Multiple-stimuli responsive soft actuators with tunable initial shapes would have substantial potential in broad technological applications, ranging from advanced sensors, smart robots to biomedical devices. However, existing soft actuators are often limited to single initial shape and are unable to reversibly reconfigure into desirable shapes, which severely restricts the multifunctions that can be integrated into one actuator. Here, a novel reconfigurable supramolecular polymer/polyethylene terephthalate (PET) bilayer actuator exhibiting multiple-stimuli responses is presented. In this bilayer actuator, the supramolecular polymer layer constructed of poly(5-Norbornene-2-carboxylic acid-1,3-cyclooctadiene) (PNCCO) and azopyridine derivative (PyAzoPy) via H-bonds provides multiple-stimuli responses: PyAzoPy offers light response and carboxylic groups in PNCCO endow the actuator with humidity response. Meanwhile thermoplastic PET layer enables the bilayer actuators to be reconfigured into various shapes by thermal stimuli. The rationally designed actuators exhibit versatile capabilities to reversibly reconfigure into a set of initial shapes and carry out multiple functions, such as photo-driven "foldback-clip" and omega-shaped crawling robots. In addition, bio-inspired plants constructed by reconfiguration of such actuators demonstrate reversible multiple-stimuli responses. It is anticipated that these novel actuators with highly tunable geometries and actuation modes would be useful to develop multifunctional devices capable of performing diverse tasks.