Electrothermal Actuators with Ultrafast Response Speed and Large Deformation

Abstract

The ability to fabricate electrothermal actuators (ETAs) simultaneously featuring ultrafast response speed (within 0.1 s), large deformation (bending for at least 360°), high figure‐of‐merit (FoM, larger than 0.1%), and low driving voltage (smaller than 1 V) in a single device is extremely important and challenging for their applications in artificial muscles, switches, and microsensors for robotics and biomimetic devices. Herein, an ETA composed of a silver nanowire (AgNW) layer and an ultrathin linear low‐density polyethylene (LLDPE) film with all the aforementioned features is designed. Due to the high conductivity of the AgNW layer and the great difference between the coefficients of thermal expansion of AgNW layer and LLDPE film as well as the huge change in the heat transfer coefficient between flat and rolled ETA, the obtained ETA exhibits an ultrafast response speed of 0.08 s for a bending angle of 360° with a FoM of 0.46% at a low driving voltage of 1 V, over one order of magnitude larger than those of reported ETAs. As a proof‐of‐concept application, the as‐prepared ETAs can be used as intelligent mechanical devices with excellent performance.

Monolithic processing of a layered flexible robotic actuator film for kinetic electronics

“…Some of the reported remarkable devices are reported such as elastomer based actuator having silver nano wire (AgNW) network embedded below the surface of PDMS (curvature: 0.26 mm −1 , driving voltage: 4.5 V, cyclic driving period: T = 120 s) 29 , and an actuator consisting of super aligned carbon nano tube (SACNT)/OPP (curvature: 0.10 mm −1 , driving voltage: 5 V, cyclic driving period: T = 25 s) 42 . Recently, an actuator based on AgNW film of the interpenetrating structure of two different diameters and low-density polyethylene (LLDPE) shows large bending actuation with low voltage (curvature: 0.88 mm −1 , driving voltage: 1 V, cyclic driving period: T = 20 s) 43 was reported. Heater electrodes of most of these actuators are uniform layers of the laminated structure.…”

Soft Actuator Materials for Electrically Driven Haptic Interfaces

“…[ 95 ] Thermal bimorph actuators consist of two materials possessing different CTE. [ 96,97 ] These actuators possess various possible configurations, with the most common being a bilayer configuration (Figure 4F). [ 98–100 ] When the actuator is heated, the material with a higher CTE expands to a larger extent than the material with a lower CTE.…”

Highly Thermally Conductive Bimorph Structures for Low-Grade Heat Energy Harvester and Energy-Efficient Actuators

“…Meanwhile, actuators have been extensively studied in recent years, aiming to achieve rapid response, low energy consumption, and sophisticated movement. ,− Bimorph actuators have received increasing attention due to their ease of fabrication and high energy efficiency with more functional integrations. − Electrothermal and photothermal actuators with bimorph structures can be effectively driven by electrical power and light to produce large displacement. ,, However, electrical and photo energies are introduced as intermediate energy sources to generate heat for thermomechanical energy conversion, resulting in low response speed and high energy loss. ,, Electronic actuators can achieve large strain and quick response, while a major drawback of high driving voltages (>1 kV) limits their applications . Ionic actuators can be driven by a much lower voltage (<10 V); however, the electrolyte environment is needed for ion transportation .…”