Photothermal and Moisture Actuator Made with Graphene Oxide and

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Cite This: ACS Appl. Mater. Interfaces 2019, 11, 21926−21934

Photothermal and Moisture Actuator Made with Graphene Oxide and Sodium Alginate for Remotely Controllable and Programmable Intelligent Devices Wen Wang,† Chenxue Xiang,‡ Dengming Sun,‡ Mufang Li,‡ Kelu Yan,† and Dong Wang*,†,‡ †

College of Chemistry, Chemical Engineering and Biotechnology, Donghua University, Shanghai 201620, China Hubei Key Laboratory of Advanced Textile Materials & Application, Wuhan 430200, China

‡

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S Supporting Information *

ABSTRACT: Functional materials with energy storage and conversion properties have been useful for actuating devices. Here, a new kind of torsional fiber-based actuator including graphene oxide (GO) and natural sodium alginate was prepared by traditional wet spinning and twisting methods, during which the fiber structure was reconstructed, and the mechanical energy was prestored. When the twisted GO/SA (graphene oxide/sodium alginate) fiber was stimulated by infrared light or moisture, the torsional structure of the fiber was activated instantaneously to generate rapid and reversible rotational motion, thus realizing the automatic release and re-storage process of rotational kinetic energy. In addition, the full revolutions of the twisted GO/SA fiber have no attenuation after 100 reversible rotations when stimulated by moisture, which proves the excellent rotational stability. Due to its excellent flexibility and wettability, the twisted GO/SA fiber can be woven into a network or prepared into a series of programmable intelligent devices, which is of great significance for future flexible intelligent electronic devices. KEYWORDS: fiber-based actuator, photothermal and moisture responsiveness, energy release and re-storage, low-cost production, programmable intelligent devices

1. INTRODUCTION Intelligent actuating materials have aroused great interest in researchers since their emergence.1,2 In the continuous development of intelligent industry, smart actuators are becoming more prosperous, which makes them have great perspectives in applications of rehabilitation physiotherapy,3−5 intelligent switch,6 artificial muscle,7,8 flexible robot,9,10 and other emerging fields. These smart devices, mainly made of two-dimensional thin films 11−13 or three-dimensional gels,14,15can bend, twist, stretch, or contract under the stimulation of external light,7,16 heat,17,18 electricity,19,20 moisture,21,22 and solvent.23 In addition, by predesigning the structures of the actuators, oriented and controllable actuating motions can be achieved, thus further promoting the intelligent process. For example, Mu et al.24 prepared a graphene-based paper actuator that can achieve self-folding performance with predesigned shapes under the stimulation of light or heat. Cheng et al.25 reported a G/GO fiber with predetermined deformation by laser, which can produce a directional bending deformation under the stimulation of moisture. Recently, the rapid development of energy materials has received extensive research attentions, especially the battery materials, including lithium ion batteries,26−28 sodium ion batteries,29,30and supercapacitors,31,32 which can repeatedly realize the storage and release of electrical energy. Can mechanical energy be prestored while fabricating the actuator © 2019 American Chemical Society

structure, and can the prestored energy be reversibly released upon the stimulation of environmental changes? Inspired by the twisting movement in nature, for example, the climbing behavior of plant tendrils33 and the entanglement of wood cells,34 several kinds of fibers with torsional structure were fabricated by mechanical pretwisting, which can convert external stimuli directly into reversible stress contraction7,17 or rotational motion.22 However, high requirements make them difficult to be used in mass production, including convenient processing, low cost, remote controllability, multistimulus response, and environment-friendly. Based on the above difficulties and research basis of our group on multidimensional actuating materials,11,35 we are attempting to design a new torsional fiber-based actuator to meet current stringent requirements. In this paper, a novel twisted GO/SA (sodium alginate) fiber-based actuator was fabricated by directly twisting the GO/SA composite gel fiber obtained by a wet spinning method. Among them, GO is widely studied and used for its excellent photothermal, hygroscopic, and mechanical properties,36,37 and its excellent dispersion in aqueous solutions makes it easy to mix with other water-soluble materials. Received: March 24, 2019 Accepted: May 28, 2019 Published: May 28, 2019 21926

DOI: 10.1021/acsami.9b05136 ACS Appl. Mater. Interfaces 2019, 11, 21926−21934

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ACS Applied Materials & Interfaces

Figure 1. Schematic diagram of the reversible rotational motion of the twisted GO/SA fiber-based actuator under on/off light irradiation and moisture. 2.2. Preparation of the GO Aqueous Solution. The GO aqueous solution was fabricated by the modified Hummers’ method and then diluted with deionized water to a concentration of 5 mg/mL. The prepared GO aqueous solution needs to be ultrasonically dispersed evenly before each use. 2.3. Preparation of the Mixed GO/SA Gel-State Spinning Solution and Calcium Chloride Coagulation Bath. The evenly dispersed GO aqueous solution was added to the sodium alginate powder (mass ratio of GO/SA were 5, 10, 15, and 20 wt %) and then mechanically stirred by a high-speed machine (1200 rpm) at room temperature for 4 h to obtain the mixed GO/SA gel-state spinning solution. The mixed GO/SA spinning solution was then defoamed at room temperature for 24 h. The calcium chloride solution of 4 wt % was prepared as the coagulation bath, and the whole preparation process was completed at room temperature. 2.4. Preparation of the Twisted GO/SA Fiber-Based Actuator. The whole wet spinning process is simple and convenient, as described in our previous method.35 First, the mixed GO/SA solution was sucked into a syringe and then slowly squeezed out through a spinning head and entered the calcium chloride coagulation bath with a constant extrusion speed to form uniform GO/SA gel fibers. Then, the two ends of the gel fiber were fixed on the twister, and the fiber twists are continuously increased through the rapid rotation of one end of the twister until the set number of twists was reached. The whole process was environmentally safe and performed at room temperature. 2.5. Characterization and Measurements. The morphology of the GO/SA fiber was characterized by a JEOL scanning electron microscope. The infrared light (150 W, Philips E27) was used to irradiate the twisted GO/SA fiber, and the temperature was tested by an infrared thermometer 125 (FLIR Thermo-Vision A40M). The tensile strength of the GO/SA fiber was characterized by an electronic universal material testing machine (Instron, 5848). The moisture

Sodium alginate, a cheap and abundant natural polysaccharide, can dissolve in water to form a gel liquid, which has the effect of stabilizing the dispersed phase well due to its natural viscosity. It was precisely for the perfect match between GO and sodium alginate that the GO/SA composite gel was made with excellent stability and can form continuous gel fibers in a calcium chloride solidification bath. Under external twisting, the fiber structure was remolded, and the applied mechanical energy was also predeposited in the twisted GO/SA fiber with a rough surface and loose structure. Due to the fast adsorption/desorption property of GO to water vapor molecules11 and the excellent swelling−deswelling behavior of sodium alginate in water,35 the twisted GO/SA fiber can generate rapid and reversible rotational motion under the stimulation of external infrared light and moisture, accompanied by changes in the fiber length and stress contraction behavior, as shown in Figure 1. In addition, the twisted GO/ SA fiber has excellent cyclic stability and excellent flexibility suitable for knitting, which endows it with great application prospects in intelligent clothing and artificial muscle.

2. METHODS 2.1. Materials. Graphite powder was purchased from XF Nanomaterials Technology Co., Ltd. (Nan Jing, China). Sodium alginate and anhydrous calcium chloride were purchased from Sinopharm Chemical Reagent Co., Ltd. (Shanghai, China). Wet spinning tools including syringes and spinning needles were obtained from Wuhan You Mao Co. LTD. All materials are used directly without further purification. 21927


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Figure 2. Schematic diagram of (a) the manufacturing process of the initial GO/SA fiber and (b) the twisting process of the initial GO/SA fiber on a twisting machine. (c) Scanning electron microscopy (SEM) images of the cross section of the initial GO/SA fiber. (d, e) Enlarged view of the initial GO/SA fiber and its surface morphology. (f) SEM images of the cross section of the twisted GO/SA fiber. (g, h) Enlarged view of the twisted GO/SA fiber and its surface morphology. (The GO concentration of (c)−(h) was controlled at 20 wt %.) actuating performance was carried out in a custom-made sealed glass instrument. The moisture content within the container was increased by continuously injecting moisture into the glass instrument, and the internal ambient humidity was precisely adjusted and controlled by the hygrometer. The revolutions and rotational speed of the twisted GO/SA fiber were recorded by a noncontact laser counter and an infrared tachometer, respectively. The corresponding videos and pictures were taken with an iPhone 7.

Supporting Information. Interestingly, the twisted GO/SA fiber formed a spiral-like configuration along the twist orientation, and the fiber structure was largely remodeled to densely packed wrinkle layers, as shown in Figure 2f−h. Additionally, both the tensile strain and tensile stress of the twisted GO/SA fiber increased slightly with the GO concentration increasing from 5 to 20 wt %, as shown in Figure S5 in the Supporting Information. 3.2. Photothermal Actuating Performance of the Twisted GO/SA Fiber. GO has excellent photothermal properties, which lay the foundation for its application in the photothermal field. Here, in order to explore the photothermal actuation behavior of the twisted GO/SA fiber, the rotational motion behavior of the twisted GO/SA fiber under infrared light was studied systematically by changing the GO concentration. The simulated reversible actuating process of the twisted GO/SA fiber under infrared light irradiation is shown in Figure 3a. When the fiber was irradiated by infrared light, the surface temperature of the twisted GO/SA fiber increased rapidly due to the photothermal effect of GO.16,24 Meanwhile, the environmental humidity around the fiber decreased, causing the water molecules in the GO sheet to evaporate immediately. The capillary force generated by the evaporation of water molecules caused the GO layer to crinkle and the internal layer distance of the twisted GO/SA fiber to further shrink,11 thus creating a torque force that promoted the twisted fiber to continue to rotate in a twisting manner. However, the twisted SA fiber alone cannot rotate under infrared light irradiation. When the infrared light was removed, the ambient humidity around the fiber rose and the excellent hygroscopicity of GO enabled the twisted GO/SA fiber to quickly adsorb water molecules and produce a torsional force. It was the torsional force that drove the overtwisted GO/SA fiber to finally return to its original state. The reversible rotational motion behavior of the twisted GO/SA fiber under infrared light irradiation is shown in Movie S1. In addition, the fiber length changed constantly during rotational motion. Figure 3b shows that the actuation strain and full revolutions of

3. RESULTS AND DISCUSSION 3.1. Preparation and Morphology Characterization of the Twisted GO/SA Fiber. The initial GO/SA gel fiber was prepared by a simple and scalable wet spinning method, which is favorable for industrial production, as shown in Figure 2a. Energy-dispersive spectrometry (EDS) images in Figure S1 show that GO is evenly dispersed in the mixed GO/SA spinning solution. The twisted GO/SA fiber was obtained by a subsequent directional twisting method, as shown in Figure 2b. The schematic diagram shows that the fiber length gradually shortened and the fiber surface morphology becomes rougher with the increase in fiber twists. Moreover, to explore the contraction ratio of the initial GO/SA gel fiber with different GO concentrations during the twisting process, the gel fiber of the same length and twist number (6000 turns/m) were prepared. Results in Figure S2 show that the contraction ratio of the gel fiber increased from 11.8 to 23.8% with the GO concentration varying from 5 to 20 wt % during the twisting process. The diameter and twist angle of the twisted GO/SA fiber were also raised with the increase in GO concentration, as shown in Figure S3. In addition, a higher GO concentration would cause the blockage of the spinneret orifice due to the viscosity of the mixed GO/SA gel-state spinning solution, so the GO concentration was controlled within 20 wt %. Figure 2c−e shows the cross section and surface topography of the initial GO/SA fiber. It can be observed that the structure of the initial GO/SA fiber is looser when compared with the initial sodium alginate (SA) fiber (Figure S4a in the Supporting Information). The twisted sodium alginate (SA) fiber without GO had a smoother surface as shown in Figure S4b in the 21928


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the twisted GO/SA fiber increased as the GO concentration rose. This was mainly because the higher GO content resulted in the absorption of more water molecules in the twisted GO/ SA fiber, thus increasing the full revolutions and actuation strain when the fiber was irradiated by infrared light. Figure 3c shows the revolutions of the twisted GO/SA fiber with different GO concentrations. It can be observed that after 20 reversible cycles, there was still no obvious fatigue phenomenon for the twisted GO/SA fiber, which proved its excellent actuating stability under infrared light irradiation. Furthermore, the rotation speed of the twisted GO/SA fiber was also studied systematically, as shown in Figure 3d. This picture shows that the rotational speed of the twisted GO/SA fiber kept increasing as the GO concentration changed from 5 to 20 wt %, while the twisting speed changed more significantly than that of the recovery speed. This can be explained as that more water molecules were absorbed in the twisted GO/SA fiber with a higher GO concentration, and when the infrared light was on, a large number of water molecules can evaporate immediately, thus producing a larger torsional force to make the fiber rotate rapidly. When the infrared light was off, it took some time for the surface temperature of the twisted GO/SA fiber to drop, and the process of the water molecule infiltration from the environment to the fiber was slow, which leads to a slower recovery speed. In addition, the twisted GO/SA fiber with a higher GO concentration can adsorb more water molecules at the same time, resulting in a greater swelling force, thus leading to a fast recovery speed. The ATR-IR spectra in Figure S6 show the interaction between the twisted GO/SA fiber and water molecules, from which it can be seen that the water molecules can conduct rapid and reversible adsorption−desorption behaviors between the fiber and environment (RH = 30%). Moreover, the increased GO concentration made the spatial structure of the fiber looser and surface cracks increased, which further accelerated the

Figure 3. (a) Schematic diagram of reversible rotation of the twisted GO/SA fiber under infrared light irradiation. (b) Actuation strain and revolution changes as a function of GO concentration under infrared light irradiation (0.5 w/cm2). (c) Cycle number of the full revolution (including twisting (triangle icon) and recovery process (circular icon)) of the twisted GO/SA fiber with a GO concentration ranging from 5 to 20 wt %. (d) Rotation speed of the twisted GO/SA fiber as a function of GO concentration under infrared light irradiation (0.5 w/cm2). (e) Revolution and rotation speed of the twisted GO/SA fiber with a 20 wt % GO concentration as a function of time under infrared light irradiation (0.5 w/cm2).

Figure 4. (a) Temperature changes of the twisted GO/SA fiber as a function of time under on/off infrared light irradiation (0.5 w/cm2). (b) Single temperature−time curve of the twisted GO/SA fiber in (a), which was framed with a dotted line. (c) Stress−time curve of the twisted GO/SA fiber under on/off infrared light irradiation (0.5 w/cm2). (d) Stress−time curve of the twisted GO/SA fiber in one single on/off irradiation, the fitting curve shows the changing rate of actuating stress when the irradiation was on or off. 21929


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Figure 5. (a) Rotation speed of the twisted GO/SA fiber with the GO concentration of 20 wt % when the humidity changed from 40 to 85%. (b) Rotation speed of the twisted GO/SA fiber as function of GO concentration changed from 5 to 20 wt %. (c) Actuation stress−time curve of the twisted GO/SA fiber upon different GO concentrations under on/off moisture stimulation for 100 s (the ambient humidity cycles between 85 and 30%). (d) Actuation stress−time curve of the twisted GO/SA fiber with a GO concentration of 20 wt % under consciously on/off moisture stimulation for nearly 1000 s (the ambient humidity cycles between 85 and 30%), where the illustration shows the change of actuating stress during the on/off moisture stimulation. (e) Full revolution changes of the twisted GO/SA fiber with different GO concentrations (5, 10, 15, and 20 wt%). (f) Rotational stability of the twisted GO/SA fiber with a 20 wt % GO concentration when the ambient humidity changed constantly from 85 to 30%.

adsorption and desorption processes of water molecules. The dependence of rotational speed and revolution on the time of the twisted GO/SA fiber is shown in Figure 3e. It shows that the rotational speed of the twisted GO/SA fiber with a GO concentration of 20 wt % can quickly reach the maximum value of 526.3 rpm/m in 2.6 s when exposed to infrared light. Moreover, the twisted GO/SA fiber rotated 125 turns within 30 s, both the rotational speed and the total revolutions were much larger than that of the tP/GO.16 The temperature−time curve of the twisted GO/SA fiber with a GO concentration of 20 wt % under on/off infrared light irradiation is shown in Figure 4a. The picture shows that the temperature change on the fiber surface was stable and maintained within 6° during the whole process of infrared light radiation. This result suggests that the photothermal actuation of the twisted GO/SA fiber can be realized in a narrow temperature range of 30 to 36 °C, which is close to the human body temperature. Figure 4b shows that the surface temperature of the twisted GO/SA fiber increased rapidly after being irradiated by infrared light, but the decline process was relatively slow, which further explained that the twisting speed of the twisted GO/SA fiber was faster than its recovery speed. In addition, the actuating stress of the twisted GO/SA fiber under infrared light was also investigated, as shown in Figure 4c. It can be observed that one single fiber can generate a stress

of up to 1.4 MPa, and the tensile stress changed regularly with on/off infrared light irradiation. Additionally, it was found by the linearly fitted slope that the upward trend of tensile stress was faster than the downward trend when the fiber was stimulated by on/off infrared light irradiation, which was consistent with the temperature change process, as shown in Figure 4d. Furthermore, the effects of temperature on the response time and full revolutions of the twisted GO/SA fiber were also investigated in detail, as shown in Figure S7 in the Supporting Information. As the ambient temperature increased from 30 to 80 °C, the response time of the twisted GO/SA fiber decreased significantly, while the full revolutions remained stable. This was mainly because the desorption speed of water molecules in the twisted fiber was closely related to the temperature, while the revolutions was related to the content of water molecules in the fiber. 3.3. Moisture Actuating Performance of the Twisted GO/SA Fiber. The twisted GO/SA fiber also exhibited rapid, reversible rotational motions in response to moisture stimulation. Different from the twisting-recovery behaviors of GO/SA fiber under photothermal stimulation, once the twisted fiber was stimulated by moisture, it would quickly absorb water and swell, resulting to the production of a greater swelling force that promoted the twisted fiber to rotate in an untwisting manner. When the ambient moisture dropped, the 21930


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Figure 6. (a) Spherical load produced a rapid forward and backward movement under on/off infrared light irradiation. (b) Smart net woven by 19 twisted GO/SA fibers had a reversible up-and-down movement under the alternating stimulation of moisture and infrared light. (b1) Top view and (b2) front view of the smart net. (b3) Video screenshot of the smart net during the entire up-and-down movement.

of water molecules on the fiber surface (Figure 5b). Figure 5c shows that when the fiber was stimulated by continuously changing the humidity, it can produce regular actuation stress due to the reversible swelling−deswelling force. In addition, under the same duration of humidity stimulation, the twisted fiber with higher GO concentration can complete more reversible swelling−deswelling cycles, indicating that the stress recovery time shortened with the increase in GO concentration. The results can be attributed to the fact that a higher GO concentration made the twisted fiber surface more wrinkled and the structure more porous, thus increasing the exchange rate of water molecules between the fiber surface and the environment. When the test time extended and the stimulation cycles increased, the actuation stress remained about 5 MPa, which is much high than that of the mammalian skeletal muscle (∼0.35 MPa),2 as shown in Figure 5d. The revolutions of the twisted GO/SA fiber with different GO concentrations are shown in Figure 5e. Results show that revolutions of the twisted GO/SA fiber were basically the same during the untwisting and recovery process, indicating that there was almost no obvious energy loss under one humidity stimulation. Furthermore, the revolutions of the twisted GO/ SA fiber gradually increased as the GO concentration changed from 5 to 20 wt %, which showed that the twisted GO/SA fiber with a high GO concentration could absorb more water molecules and generate a relatively larger swelling degree. Rotational stability is critical for torsional fiber-based actuators. Figure 5f shows that, after 100 cycles of continuous moisture stimulations, the revolutions of the twisted GO/SA fiber were basically unchanged, which further exhibits that both the torsional structure and rotational motion of the twisted GO/ SA fiber are very stable and can be well used in flexible intelligent actuating devices.

water in the twisted fiber desorbed and generated a large deswelling force. It was the deswelling force that made the partially untwisted GO/SA fiber to finally return to its initial state. Figure 5a shows the rotational speed of the twisted GO/ SA fiber when it was exposed to different humidity conditions. As the humidity increased, the untwisting and recovery speed of the twisted GO/SA fiber increased simultaneously. However, unlike photothermal stimulation, the recovery speed of the twisted GO/SA fiber was much higher than that of the untwisting speed when the fiber was stimulated by moisture. This can be explained as that during the untwisting process, water molecules gradually permeated into the twisted GO/SA fiber and generated a relatively uniform swelling force, so the untwisting speed was relatively stable and slow. Once the fiber has entered a low-moisture environment, a lot of water molecules on the fiber surface evaporate instantly, thus producing a large contraction and torsional force, which promoted the fiber to rotate instantly and rapidly. In addition, the structure change during infrared light irradiation was examined by continuously recording the IR spectra. Results in Figure S8 show that when the twisted GO/SA fiber was exposed to a relatively high humidity environment (RH = 85%) for a few seconds, the absorption intensity of the hydroxyl peak (3300 cm−1) increased significantly. After the environmental humidity dropped, the water molecules on the fiber would quickly spread to the environment, and the absorption peak strength of the hydroxyl peak gradually returned to the initial state. This result shows that the adsorption−desorption behavior between the twisted GO/SA fiber and water molecules can still be completed rapidly and reversibly even under high-moisture stimulation. Moreover, the recovery speed of the twisted GO/SA fiber increased from 7280 to 14,067 rpm/m as the GO concentration changed from 5 to 20 wt %, which was closely related to the evaporation rate 21931


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Figure 7. (a) Whole structure of the smart elevating bridge, including the rotating shaft consisting of six twisted GO/SA fibers, bridge floor, and traction line. (b) Video screenshot of the bridge floor being lifted when the right side of the rotational axis was stimulated by moisture. (c) Video screenshot of the bridge floor being lowered when the left side of the rotational axis was stimulated by moisture.

3.4. Application. Inspired by the reversible rotational motion of the twisted GO/SA fiber stimulated by infrared light, we prepared a remotely controlled manipulator by fixing one end of the twisted GO/SA fiber on the glass rod and connected the other end to a spherical load. Then, the spherical load can be reversibly moved by switching the infrared light irradiation. A series of video screenshots of the whole movement is shown in Figure 6a. As can be seen from the figure, the spherical load rolled 20.12° within 2.72 s under infrared light irradiation and returned to its original state within 2 s when the infrared light was off. Both the moving speed and vertical displacement (34 mm) of the twisted GO/ SA fiber were greater than the G/GO fiber25 and GO film.38 The video file is shown in Movie S2 in the Supporting Information. Additionally, the twisted GO/SA fiber was flexible and strong enough to be woven directly into a smart net, which can generate the output force of 0.475 N and the unit mass force of up to 3.96×104 N/kg, respectively, under the infrared light irradiation (Figure 6b1,b2 and Computation part in the Supporting Information). The power is significantly greater than that of the adult’s arm muscle (about 180 N/ kg).39 The smart net was then suspended and fixed to a wooden frame for further testing. Stimulated alternately by moisture and infrared light irradiation, the copper coil with a weight of 3.57 g (290 times heavier than the net) quickly descended 9 mm in height and then gradually returned to its original height (Figure 6b3 and Movie S3 in Supporting Information). As the copper coil returned, the power density generated by the net reached 16.4 W/kg (Computation part in the Supporting Information), which was much larger than that of the GM paper stimulated by infrared radiation40 and the polymer actuator in response to moisture.2

In addition, the ubiquitous existence of water resources in nature makes the GO/SA fiber a promising green energy material in the future. Here, inspired by the convenience and functionality of the movable elevating bridge, a moisturestimulated elevating bridge was prepared, and the controllable rise and fall process of the bridge floor can be well programmed by the stimulation of external moisture change, as shown in Figure 7. Figure 7a shows the overall structure of the smart elevating bridge. It can be observed that the rotational shaft, which also served as the supporting structure of the bridge floor, was composed of the twisted GO/SA fiber and placed horizontally on the bridge frame. As soon as the right side of the rotational shaft was stimulated by moisture, the twisted GO/SA fiber could quickly rotate, which shortened the traction line attached to the bridge floor, making the bridge floor rise. The detailed rising process of the bridge floor is shown in Figure 7b and Movie S4 in the Supporting Information. When the bridge floor rose to its highest height, the left side of the rotational shaft was stimulated by moisture, and the twisted GO/SA fiber would produce a rapid untwisting rotational movement, extending the traction line and lowering the bridge floor quickly, as shown in Figure 7c and Movie S5 in the Supporting Information. This programmable control behavior successfully realized the lifting and lowering process of the elevating bridge under remote operation.

4. CONCLUSIONS In summary, a novel twisted GO/SA fiber-based actuator was fabricated by twisting the gel fiber containing GO and natural sodium alginate, during which the mechanical energy was predeposited. The addition of GO endowed the twisted GO/ SA fiber with an excellent photothermal property and a rapid adsorption−desorption property between the twisted GO/SA 21932


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ACS Applied Materials & Interfaces fiber and water molecules, which realized the multistimulus responses under photothermal and moisture stimulation. Results show that the twisted GO/SA fiber can undergo rapid and reversible rotational motions, accompanied by changes in the fiber length and stress when exposed to remote infrared irradiation and moisture. In addition, the full revolutions of the twisted GO/SA fiber have no attenuation after 100 reversible rotations when stimulated by moisture, which proves the excellent rotational stability. Due to its excellent flexibility and wettability, the twisted GO/SA fiberbased actuator can be fabricated into a series of bionic intelligent devices, including remotely controlled manipulator, light-humidity controllable smart net, and programmable smart elevating bridge, which is of great significance for future flexible intelligent electronic devices.

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from robots and sensor skin to energy harvesters. Adv. Mater. 2014, 26, 149−162. (2) Ma, M.; Guo, L.; Anderson, D. G.; Langer, R. Bio-inspired Polymer Composite Actuator and Generator Driven by Water Gradients. Science 2013, 339, 186−189. (3) Hines, L.; Petersen, K.; Lum, G. Z.; Sitti, M. Soft Actuators for Small-Scale Robotics. Adv. Mater. 2017, 29, 1603483. (4) Kaneko, D.; Gong, J. P.; Osada, Y. Polymer gels as soft and wet chemomechanical systemsan approach to artificial muscles. J. Mater. Chem. 2002, 12, 2169−2177. (5) Rosso, F.; Marino, G.; Giordano, A.; Barbarisi, M.; Parmeggiani, D.; Barbarisi, A. Smart materials as scaffolds for tissue engineering. J. Cell. Physiol. 2005, 203, 465−470. (6) Sun, H.; Ang, H. M.; Tadé, M. O.; Wang, S. Co3O4 nanocrystals with predominantly exposed facets: Synthesis, environmental and energy applications. J. Mater. Chem. A 2013, 1, 14427−14442. (7) Lima, M. D.; Li, N.; De Andrade, M. J.; Fang, S.; Oh, J.; Spinks, G. M.; Kozlov, M. E.; Haines, C. S.; Suh, D.; Foroughi, J.; Kim, S. J.; Chen, Y.; Ware, T.; Shin, M. K.; Machado, L. D.; Fonseca, A. F.; Madden, J. D. W.; Voit, W. E.; Galvão, D. S.; Baughman, R. H. Electrically, chemically, and photonically powered torsional and tensile actuation of hybrid carbon nanotube yarn muscles. Science 2012, 338, 928−932. (8) Shi, H. K.; Kwon, C. H.; Park, K.; Mun, T. J.; Lepró, X.; Baughman, R. H.; Spinks, G. M.; Kim, S. J. Bio-inspired, MoisturePowered Hybrid Carbon Nanotube Yarn Muscles. Sci. Rep. 2016, 6, 23016. (9) Ilievski, F.; Mazzeo, A. D.; Shepherd, R. F.; Chen, X.; Whitesides, G. M. Soft Robotics for Chemists. Angew. Chem., Int. Ed. 2015, 123, 1930−1935. (10) Migliorini, L.; Santaniello, T.; Yan, Y.; Lenardi, C.; Milani, P. Low-voltage electrically driven homeostatic hydrogel-based actuators for underwater soft robotics. Sens. Actuators, B 2016, 228, 758−766. (11) Wang, W.; Xiang, C.; Zhu, Q.; Zhong, W.; Li, M.; Yan, K.; Wang, D. Multi-stimulus responsive actuator with GO and carbon nanotube/PDMS bilayer structure for flexible and smart devices. ACS Appl. Mater. Interfaces 2018, 10, 27215−27223. (12) Han, D.-D.; Zhang, Y.-L.; Liu, Y.; Liu, Y.-Q.; Jiang, H.-B.; Han, B.; Fu, X.-Y.; Ding, H.; Xu, H. L.; Sun, H.-H. Bioinspired Graphene Actuators Prepared by Unilateral UV Irradiation of Graphene Oxide Papers. Adv. Funct. Mater. 2015, 25, 4548−4557. (13) Wang, C.; Sim, K.; Chen, J.; Kim, H.; Rao, Z.; Li, Y.; Chen, W.; Song, J.; Verduzco, R.; Yu, C. Soft Ultrathin Electronics Innervated Adaptive Fully Soft Robots. Adv. Mater. 2018, 30, 1706695. (14) Ma, C.; Lu, W.; Yang, X.; He, J.; Le, X.; Wang, L.; Zhang, J.; Serpe, M. J.; Huang, Y.; Chen, T. Bioinspired Anisotropic Hydrogel Actuators with On-Off Switchable and Color-Tunable Fluorescence Behaviors. Adv. Funct. Mater. 2018, 28, 1704568. (15) Teodorescu, F.; Oz, Y.; Quéniat, G.; Abderrahmani, A.; Sanyal, R.; Sanyal, A.; Boukherroub, R.; Szuneits, S. Photothermally triggered on-demand insulin release from reduced graphene oxide modified hydrogels. J. Controlled Release 2017, 246, 164−173. (16) Shi, Q.; Li, J.; Hou, C.; Shao, Y.; Zhang, Q.; Li, Y.; Wang, H. A remote controllable fiber-type near-infrared light-responsive actuator. Chem. Commun. 2017, 53, 11118−11121. (17) Kim, H.; Lee, J. A.; Sim, H. J.; Lima, M. D.; Baughman, R. H.; Kim, S. J. Temperature-Responsive Tensile Actuator Based on Multiwalled Carbon Nanotube Yarn. Nano-Micro Lett. 2016, 8, 254−259. (18) Haines, C. S.; Lima, M. D; Li, N.; Spinks, G. M.; Foroughi, J.; Madden, J. D. W.; Kim, S. H.; Fang, S.; de Andrade, M. J.; Göktepe, F.; Göktepe, Ö .; Mirvakili, S. M.; Naficy, S.; Lepró, X.; Oh, J.; Kozlov, M. E.; Kim, S. J.; Xu, X.; Swedlove, B. J.; Wallace, G. G.; Baughman, R. H. Artificial muscles from fishing line and sewing thread. Science 2014, 343, 868−872. (19) Mirfakhrai, T.; Oh, J.; Kozlov, M.; Fok, E. C. W.; Zhang, M.; Fang, S.; Baughman, R. H.; Madden, J. D. W. Electrochemical actuation of carbon nanotube yarns. Smart Mater. Struct. 2007, 16, S243.

ASSOCIATED CONTENT

* Supporting Information S

The Supporting Information is available free of charge on the ACS Publications website at DOI: 10.1021/acsami.9b05136. EDS mapping of the twisted GO/SA fiber, where (a) shows the overall distribution of three elements in the fiber, (b) shows the distribution of carbon elements, (c) shows the distribution of oxygen elements, and (d) shows the distribution of sodium elements PDF) Reversible rotational motion behavior of the twisted GO/SA fiber under infrared light irradiation (AVI) Moving speed and vertical displacement (34 mm) of the twisted GO/SA fiber (AVI) Copper coil with a weight of 3.57 g quickly descending 9 mm in height and then gradually returned to its original height (AVI) Detailed rising process of the bridge floor (AVI) Twisted GO/SA fiber producing rapid untwisting rotational movement lowering the bridge floor when stimulated by moisture (AVI)

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AUTHOR INFORMATION

Corresponding Author

*E-mail: [email protected];[email protected]. Tel: +86-27-59367691. ORCID

Dong Wang: 0000-0002-8139-8502 Notes

The authors declare no competing financial interest.

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ACKNOWLEDGMENTS This study was supported by the National Natural Science Foundation of China (51873166, 51873165), Science and Technology Innovation Projects of Hubei Province (2017AHB065), Central Guidance for Local Science and Technology Development Projects (2018ZYYD057), Science and Technology Program of Wuhan Technology Bureau (2017060201010165) and National Key Research and Development Program of China (2016YFC0206101). The authors also acknowledge the financial support from Wuhan Advanced Fiber Engineering Technology Research Center.

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REFERENCES

(1) Bauer, S.; Bauer-Gogonea, S.; Graz, I.; Kaltenbrunner, M.; Keplinger, C.; Schwödiauer, R. 25th anniversary article: A soft future: 21933


Research Article

ACS Applied Materials & Interfaces (20) Hung, N. T.; Nugraha, A. R. T.; Saito, R. Charge-induced electrochemical actuation of armchair carbon nanotube bundles. Carbon 2017, 118, 278−284. (21) He, S.; Chen, P.; Qiu, L.; Wang, B.; Sun, X.; Xu, Y.; Peng, H. A Mechanically Actuating Carbon-Nanotube Fiber in Response to Water and Moisture. Angew. Chem., Int. Ed. 2015, 54, 14880−14884. (22) Gu, X.; Fan, Q.; Yang, F.; Cai, L.; Zhang, N.; Zhou, W.; Zhou, W.; Xie, S. Hydro-actuation of hybrid carbon nanotube yarn muscles. Nanoscale 2016, 8, 17881−17886. (23) Chen, P.; Xu, Y.; He, S.; Sun, X.; Pan, S.; Deng, J.; Chen, D.; Peng, H. Hierarchically arranged helical fibre actuators driven by solvents and vapours. Nat. Nanotechnol. 2015, 10, 1077−1083. (24) Mu, J.; Hou, C.; Wang, H.; Li, Y.; Zhang, Q.; Zhu, M. Origamiinspired active graphene-based paper for programmable instant selffolding walking devices. Sci. Adv. 2015, 1, e1500533. (25) Cheng, H.; Liu, J.; Zhao, Y.; Hu, C.; Zhang, Z.; Chen, N.; Jiang, L.; Qu, L. Graphene fibers with predetermined deformation as moisture-triggered actuators and robots. Angew. Chem., Int. Ed. 2013, 52, 10482−10486. (26) Zhang, C.; Mahmood, N.; Yin, H.; Liu, F.; Hou, Y. Synthesis of Phosphorus-Doped Graphene and its Multifunctional Applications for Oxygen Reduction Reaction and Lithium Ion Batteries. Adv. Mater. 2013, 25, 4932−4937. (27) Tang, T.; Hou, Y. Multifunctionality of Carbon-based Frameworks in Lithium Sulfur Batteries. Electrochem. Energy Rev. 2018, 1, 403−432. (28) Wang, Y.; Adekoya, D.; Sun, J.; Tang, T.; Qiu, H.; Xu, L.; Zhang, S.; Hou, Y. Manipulation of Edge-Site Fe−N2 Moiety on Holey Fe, N Codoped Graphene to Promote the Cycle Stability and Rate Capacity of Li−S Batteries. Adv. Funct. Mater. 2019, 29, 1807485. (29) Liu, Y.; Liu, X.; Wang, T.; Fan, L. Z.; Jiao, L. Research and application progress on key materials for sodium-ion batteries. Sustainable Energy Fuels 2017, 1, 986−1006. (30) Hwang, J. Y.; Myung, S. T.; Sun, Y. K. Sodium-ion batteries: present and future. Chem. Soc. Rev. 2017, 46, 3529. (31) Salanne, M.; Rotenberg, B.; Naoi, K.; Kaneko, K.; Taberna, P. L.; Grey, C. P.; Dunn, B.; Simon, P. Efficient storage mechanisms for building better supercapacitors. Nat. Energy 2016, 1, 16070. (32) González, A.; Goikolea, E.; Barrena, J. A.; Mysyk, R. Review on supercapacitors: Technologies and materials. Renewable Sustainable Energy Rev. 2016, 58, 1189−1206. (33) Wang, J.-S.; Wang, G.; Feng, X.-Q.; Kitamura, T.; Kang, Y. L.; Yu, S.-W.; Qin, Q.-H. Hierarchical chirality transfer in the growth of Towel Gourd tendrils. Sci. Rep. 2013, 3, 3102. (34) Plaza, N.; Zelinka, S. L.; Stone, D. S.; Jakes, J. E. Plant-based torsional actuator with memory. Smart Mater. Struct. 2013, 22, No. 072001. (35) Wang, W.; Xiang, C.; Liu, Q.; Li, M.; Zhong, W.; Yan, K.; Wang, D. Natural alginate fiber-based actuator driven by water or moisture for energy harvesting and smart controller applications. J. Mater. Chem. A 2018, 6, 22599−22608. (36) Zhu, Y.; Murali, S.; Cai, W.; Li, X.; Suk, J. W.; Potts, J. R.; Ruoff, R. S. Graphene and Graphene Oxide: Synthesis, Properties, and Applications. Adv. Mater. 2010, 22, 3906−3924. (37) Dikin, D. A.; Stankovich, S.; Zimney, E. J.; Piner, R. D.; Dommett, G. H. B.; Evmenenko, G.; Nguyen, S. T.; Ruoff, R. S. Preparation and characterization of graphene oxide paper. Nature 2007, 448, 457−460. (38) Cheng, H.; Zhao, F.; Xue, J.; Shi, G.; Jiang, L.; Qu, L. One Single Graphene Oxide Film for Responsive Actuation. ACS Nano 2016, 10, 9529−9535. (39) Yamada, M.; Kondo, M.; Mamiya, J.-c.; Yu, Y.; Kinoshita, M.; Barrett, C. J.; Ikeda, T. Photomobile polymer materials: towards lightdriven plastic motors. Angew. Chem., Int. Ed. 2008, 47, 4986−4988. (40) Mu, J.; Hou, C.; Zhu, B.; Wang, H.; Li, Y.; Zhang, Q. A multiresponsive water-driven actuator with instant and powerful performance for versatile applications. Sci. Rep. 2015, 5, 9503.

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Photothermal and Moisture Actuator Made with Graphene Oxide and

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