Directional, Low‐Energy Driven Thermal Actuating Bilayer Enabled by Coordinated Submolecular Switching

Abstract

The authors reveal a thermal actuating bilayer that undergoes reversible deformation in response to low-energy thermal stimuli, for example, a few degrees of temperature increase. It is made of an aligned carbon nanotube (CNT) sheet covalently connected to a polymer layer in which dibenzocycloocta-1,5-diene (DBCOD) actuating units are oriented parallel to CNTs. Upon exposure to low-energy thermal stimulation, coordinated submolecular-level conformational changes of DBCODs result in macroscopic thermal contraction. This unique thermal contraction offers distinct advantages. It's inherently fast, repeatable, low-energy driven, and medium independent. The covalent interface and reversible nature of the conformational change bestow this bilayer with excellent repeatability, up to at least 70 000 cycles. Unlike conventional CNT bilayer systems, this system can achieve high precision actuation readily and can be scaled down to nanoscale. A new platform made of poly(vinylidene fluoride) (PVDF) in tandem with the bilayer can harvest low-grade thermal energy and convert it into electricity. The platform produces 86 times greater energy than PVDF alone upon exposure to 6 °C thermal fluctuations above room temperature. This platform provides a pathway to low-grade thermal energy harvesting. It also enables low-energy driven thermal artificial robotics, ultrasensitive thermal sensors, and remote controlled near infrared (NIR) driven actuators.

An Electrothermal and Magnetic Dual‐Modal Actuator toward Soft Self‐Sensing Robots

“…Because the soft actuators can spontaneously convert the external stimuli such as electricity, light, humidity and magnetic field into mechanical deformation, they show promising applications in soft robotics, aerospace engineering and intelligent artificial muscles. [9] The traditional soft material actuators were mainly actuated by single mode, such as electric, [17][18][19] magnetic, [20][21][22] and thermal [23][24][25] actuation. Dai et al proposed a soft magnetic actuator with bionic sandwich structure, and this work focused on designing highly deformable actuators and functions in emerging areas of soft robotics.…”

Silicon Distribution-Induced Actuation Film with Bidirectional Bending Deformation and Versatile Bionic Applications

“…Among them, electric, thermal, and magnetic stimulation-responsive actuation materials have great advantages in actuation stress and were often designed as robot grips and artificial muscles. 21,25,27 Its defects are the consumption and dependence on nonrenewable resources, such as electric, heat, and magnetism, and the external circuit is needed in the preparation process, which will weaken the properties of the actuation material to a certain extent. Solvent materials have some defects in environmental protection and regeneration, so there are some defects in practical application.…”

“…In recent years, with the acceleration of intelligence process, the research on flexible actuators has generally increased, and its research content mainly focuses on one-dimensional fiber materials and two-dimensional film materials. For fiber materials with linear structure, the actuation force is mainly concentrated on the axial direction, and their research and applications are focused on the axial stretch controller and artificial muscle for electric stimulus response. − For two-dimensional film-based actuation materials, due to the wide selection of materials and film-forming process, the research scope is wide, and the corresponding derivative of thin-film-based actuator materials are also numerous. − At present, the stimulation sources of film-based actuation materials are widely distributed in optical, , electrical, − magnetic, , thermal, , wet, , solvent, , and so on. Among them, electric, thermal, and magnetic stimulation-responsive actuation materials have great advantages in actuation stress and were often designed as robot grips and artificial muscles. ,, Its defects are the consumption and dependence on nonrenewable resources, such as electric, heat, and magnetism, and the external circuit is needed in the preparation process, which will weaken the properties of the actuation material to a certain extent.…”

“…13−15 For two-dimensional film-based actuation materials, due to the wide selection of materials and film-forming process, the research scope is wide, and the corresponding derivative of thin-film-based actuator materials are also numerous. 16−18 At present, the stimulation sources of film-based actuation materials are widely distributed in optical, 19,20 electrical, 21−23 magnetic, 24,25 thermal, 26,27 wet, 1,28 solvent, 29,30 and so on. Among them, electric, thermal, and magnetic stimulation-responsive actuation materials have great advantages in actuation stress and were often designed as robot grips and artificial muscles.…”

Reconfigurable, Reversible, and Redefinable Deformation of GO Based on Quantum-Confined-Superfluidics Effect

“…To date, bilayer actuators based on different materials (e.g., metal, 25 metal oxides, 26 polymer, 27 carbon, 28 and biomaterials 29 ) have been developed rapidly. As a typical one, graphene oxide (GO) has emerged as a versatile smart material for bilayer actuators.…”