Reconfigurable Soft Actuators with Multiple‐Stimuli Responses

Abstract

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 Ω‐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.

Development and challenges of smart actuators based on water-responsive materials

“…2.2.1 Polymer material-based actuators. Hydrophilic groups in WR polymers have strong polarities, such as carboxylic groups, 85,86 amides, 87 esters, 88 and ether bonds composed of oxygen-containing groups. 89,90 They can be easily combined with water to form hydrogen bonds, resulting in the volume expansion of the polymer.…”

Programmable Stimuli-Responsive Actuators for Complex Motions in Soft Robotics: Concept, Design and Challenges

“…This solution depends on the stimuli-responsive behaviour of the transducer and remains widely unexplored. As shown in Figure 11a, Zhao et al [176] used a supramolecular polymer in a bilayer configuration, responding both to UV light and humdity changes through incorporation of multiple stimuli-responsive groups [176]. Ryabchun et al [86] integrated hydrazone photoswitches into LC, allowing stable reversible actuation using different light wavelengths [86].…”

Synthesis of Self‐healing and Light‐, Thermal‐, and Humidity‐induced Deformative Polyurethane Actuator

“…Intelligent actuating materials show promising applications prospect in bionics, [1,2] artificial muscles, [3,4] soft robots, [5,6] and sensors [7,8] owing to their potentials in transferring external energies into macroscopic changes of shape and/or size in response to diverse stimuli. [9][10][11][12][13][14] Recently, different kinds of actuators have been developed, such as hydrogels, [15] liquid crystals, [16,17] , and carbon nanomaterials, [18] nevertheless, single specific stimuliresponsive properties of these materials restricted their applications in complicated circumstances.…”