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Journal ArticleDOI: 10.1021/ACSNANO.0C10797

Self-Locomotive Soft Actuator Based on Asymmetric Microstructural Ti3C2Tx MXene Film Driven by Natural Sunlight Fluctuation.

02 Mar 2021-ACS Nano (American Chemical Society)-Vol. 15, Iss: 3, pp 5294-5306
Abstract: Soft actuators and microrobots that can move spontaneously and continuously without artificial energy supply and intervention have great potential in industrial, environmental, and military applications, but still remain a challenge. Here, a bioinspired MXene-based bimorph actuator with an asymmetric layered microstructure is reported, which can harness natural sunlight to achieve directional self-locomotion. We fabricate a freestanding MXene film with an increased and asymmetric layered microstructure through the graft of coupling agents into the MXene nanosheets. Owing to the excellent photothermal effect of MXene nanosheets, increased interlayer spacing favoring intercalation/deintercalation of water molecules and its caused reversible volume change, and the asymmetric microstructure, this film exhibits light-driven deformation with a macroscopic and fast response. Based on it, a soft bimorph actuator with ultrahigh response to solar energy is fabricated, showing natural sunlight-driven actuation with ultralarge amplitude and fast response (346° in 1 s). By utilizing continuous bending deformation of the bimorph actuator in response to the change of natural sunlight intensity and biomimetic design of an inchworm to rectify the repeated bending deformation, an inchwormlike soft robot is constructed, achieving directional self-locomotion without any artificial energy and control. Moreover, soft arms for lifting objects driven by natural sunlight and wearable smart ornaments that are combined with clothing and produce three-dimensional deformation under natural sunlight are also developed. These results provide a strategy for developing natural sunlight-driven soft actuators and reveal great application prospects of this photoactuator in sunlight-driven soft biomimetic robots, intelligent solar-energy-driven devices in space, and wearable clothing.

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Topics: Bimorph (54%)
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13 results found


Journal ArticleDOI: 10.1021/ACSAMI.1C09653
Jie Wei1, Shuai Jia1, Chao Ma2, Ziqiang Shao1Institutions (2)
Abstract: Although humidity-responsive actuators serve as a promising candidate in smart wearables, artificial muscles, and biomimetic devices, most of them derived from synthetic polymers could not simultaneously achieve multifunctional properties. In this work, a cellulose nanofiber (CNF)-based film actuator with high mechanical properties, excellent Joule heating, and antibacterial capability is successfully constructed by integrating with Ti3C2Tx (MXene) and tannic acid (TA) via a vacuum-assisted filtration approach. Owing to the unique nacrelike structure and strong hydrogen bonds, the tensile strength and toughness of the composite film could reach 275.4 MPa and 10.2 MJ·m-3, respectively. Importantly, the hydrophilic nature of CNFs and alterable interlayer spacing of MXene nanosheets endow the composite film with sensitive humidity response and extraordinary stability (1000 cycles). With the assistance of MXene nanosheets and TA, the composite film could not only present outstanding Joule heating but also possess remarkable antibacterial properties against both Gram-negative Escherichia coli and Gram-positive Staphylococcus aureus. Benefiting from the above merits, the proof-of-concept smart garment is assembled by the as-prepared film and is capable of regulating humidity and temperature.

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2 Citations


Journal ArticleDOI: 10.1016/J.CARBON.2021.05.048
Liang Yin1, Hui Kang1, Haoxiang Ma2, Jingfeng Wang1  +4 moreInstitutions (2)
01 Sep 2021-Carbon
Abstract: The controllable construction of lightweight, highly conductive, porous and flexible Ti3C2Tx MXene film is crucial in achieving high-performance electromagnetic interference (EMI) shielding and the next generation of high-rate energy storage materials, but it is difficult to produce. Herein, the focused sunlight was used to stimulate the photothermal effect of MXene, which makes the free water between the layers of the conventional compact MXene film vaporized instantaneously, and then a macroporous MXene film with 3D architectures was obtained in just a few seconds. Such macroporous MXene film is lightweight and flexible, with high conductivity (≈1000 S cm−1), good hydrophobicity and environmental stability. Therefore, the absolute shielding effectiveness of the macroporous MXene film can be as high as 88333 dB cm2 g−1, indicating its potential applications in EMI shielding materials for aerospace. Furthermore, based on the highly open pore structure and more exposed surface area, this MXene film possesses a higher capacitance (380 F g−1) and good rate capability, enabling it to demonstrate attractive prospects in high-rate energy storage. This work provides an ingenious way to create macroporous MXene film and can guide future work on exploring the wider use of MXene-based materials.

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2 Citations


Journal ArticleDOI: 10.1002/ANIE.202108058
Ying Hu1, Qixiao Ji1, Majing Huang1, Longfei Chang1  +6 moreInstitutions (3)
06 Sep 2021-Angewandte Chemie
Abstract: Developing self-oscillating soft actuators that enable autonomous, continuous, and directional locomotion is significant in biomimetic soft robotics fields, but remains great challenging. Here, an untethered soft photoactuators based on covalently-bridged black phosphorus-carbon nanotubes heterostructure with self-oscillation and phototactic locomotion under constant light irradiation is designed. Owing to the good photothermal effect of black phosphorus heterostructure and thermal deformation of the actuator components, the new actuator assembled by heterostructured black phosphorus, polymer and paper produces light-driven reversible deformation with fast and large response. By using this actuator as mechanical power and designing a robot configuration with self-feedback loop to generate self-oscillation, an inchworm-like actuator that can crawl autonomously towards the light source is constructed. Moreover, due to the anisotropy and tailorability of the actuator, an artificial crab robot that can simulate the sideways locomotion of crabs and simultaneously change color under light irradiation is also realized.

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Topics: Directional locomotion (62%), Actuator (54%), Soft robotics (53%)

2 Citations


Journal ArticleDOI: 10.1021/ACSNANO.1C03950
Xiao Xiao1, He Ma1, Xinping Zhang1Institutions (1)
09 Jul 2021-ACS Nano
Abstract: Due to their high flexibility and adaptability, bionic robots have great potential in applications such as healthcare, rescue, and surveillance. The flexible actuator is an essential component of the bionic robot and determines its performance. Even though much progress has been achieved in bionic robot research, there still exists a great challenge in preparing a flexible actuator with a large stroke, high sensitivity, fast response, low triggering power, and long lifetime. This study presents a flexible actuator based on a paraffin wax and Ti3C2Tx MXene (PW-MX) film composite. Such a flexible actuator delivers an excellent actuation performance, including a large curvature change (2.2 × 102 m-1), high thermal sensitivity (4.6 m-1/°C), low triggering power of light (76 mW/cm2), wavelength selectivity, fast response (0.38 s), and long lifetime (>20000 cycles). Due to the high thermal sensitivity and the strong infrared absorption of the PW-MX film, crawling motion of an inchworm robot based on PW-MX film can be triggered by infrared irradiation from the human finger. To mimic living organisms with bioluminescence, we prepared a PW-MX actuator with green fluorescence by doping PW-MX film with CdSe/ZnS quantum dots. The integration of luminescent function enables the PW-MX actuator to deliver information under light stimulation and to camouflage under a background of green foliage actively. With its merits of ease of fabrication and high actuation performance, the flexible PW-MX actuator is expected to lend itself to more applications in the future.

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Topics: Actuator (56%)

1 Citations


Journal ArticleDOI: 10.1021/ACSAMI.1C08525
Lin Dezhao1, Fan Yang1, Di Gong1, Lin Zhihong1  +5 moreInstitutions (1)
Abstract: Magnetoactive elastomers (MAEs), one kind of typical novel magnetoactive driver applied in the soft robotic area, have become one of the research hotspots as they can provide biologically friendly driving methods with safe, preprogrammed, and easy-to-implement properties. In this study, novel MAEs embedding soft magnetic iron microparticles with radial chains, which can be molded in one piece, achieve 3D deformation, and co-work between multiple MAEs under single homogeneous stimuli, are proposed. Then, two kinds of novel magnetoactive drivers are established based on the proposed MAEs, which can achieve the synchronous pumping behavior of heart and the extension behavior of muscle under applied homogeneous magnetic fields. The experimental data show that (1) for the pumping behavior, the maximum instantaneous flow rate and total pumping volume can reach 200.1 and 52.3 mL/min, respectively, under 120 BPM applied harmonic magnetic field with 0-300 mT amplitude; (2) the muscle extension behavior can achieve a strain of 0.925 without a loading mass and carry a load of 40 times its own weight with a pronounced dynamic movement. It should be emphasized that the behavior of the proposed magnetoactive drivers can be excited by remote homogeneous magnetic fields, and it has great application potential in biomimetic or bioinspired soft driving systems.

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1 Citations


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58 results found


Open accessJournal ArticleDOI: 10.1002/ADMA.201102306
Michael Naguib1, Murat Kurtoglu1, Volker Presser1, Jun Lu2  +5 moreInstitutions (2)
04 Oct 2011-Advanced Materials
Abstract: Currently, however, there are relatively few such atomically layered solids. [ 2–5 ] Here, we report on 2D nanosheets, composed of a few Ti 3 C 2 layers and conical scrolls, produced by the room temperature exfoliation of Ti 3 AlC 2 in hydrofl uoric acid. The large elastic moduli predicted by ab initio simulation, and the possibility of varying their surface chemistries (herein they are terminated by hydroxyl and/or fl uorine groups) render these nanosheets attractive as polymer composite fi llers. Theory also predicts that their bandgap can be tuned by varying their surface terminations. The good conductivity and ductility of the treated powders suggest uses in Li-ion batteries, pseudocapacitors, and other electronic applications. Since Ti 3 AlC 2 is a member of a 60 + group of layered ternary carbides and nitrides known as the MAX phases, this discovery opens a door to the synthesis of a large number of other 2D crystals. Arguably the most studied freestanding 2D material is graphene, which was produced by mechanical exfoliation into single-layers in 2004. [ 1 ] Some other layered materials, such as hexagonal BN, [ 2 ] transition metal oxides, and hydroxides, [ 4 ] as well as clays, [ 3 ] have also been exfoliated into 2D sheets. Interestingly, exfoliated MoS 2 single layers were reported as early as in 1986. [ 5 ] Graphene is fi nding its way to applications ranging from supercapacitor electrodes [ 6 ] to reinforcement in composites. [ 7 ] Although graphene has attracted more attention than all other 2D materials combined, its simple chemistry and the weak van der Waals bonding between layers in multilayer structures limit its use. Complex, layered structures that contain more than one element may offer new properties because they

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Topics: Exfoliation joint (61%)

4,043 Citations


Journal ArticleDOI: 10.1021/NN204153H
Michael Naguib1, Olha Mashtalir, Joshua Carle, Volker Presser  +4 moreInstitutions (2)
13 Feb 2012-ACS Nano
Abstract: Herein we report on the synthesis of two-dimensional transition metal carbides and carbonitrides by immersing select MAX phase powders in hydrofluoric acid, HF. The MAX phases represent a large (>60 members) family of ternary, layered, machinable transition metal carbides, nitrides, and carbonitrides. Herein we present evidence for the exfoliation of the following MAX phases: Ti2AlC, Ta4AlC3, (Ti0.5,Nb0.5)2AlC, (V0.5,Cr0.5)3AlC2, and Ti3AlCN by the simple immersion of their powders, at room temperature, in HF of varying concentrations for times varying between 10 and 72 h followed by sonication. The removal of the “A” group layer from the MAX phases results in 2-D layers that we are labeling MXenes to denote the loss of the A element and emphasize their structural similarities with graphene. The sheet resistances of the MXenes were found to be comparable to multilayer graphene. Contact angle measurements with water on pressed MXene surfaces showed hydrophilic behavior.

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Topics: MXenes (69%), MAX phases (67%), Carbide (51%)

2,094 Citations


Journal ArticleDOI: 10.1016/J.COMPOSITESA.2010.03.005
Yanjun Xie1, Yanjun Xie2, Callum A. S. Hill2, Zefang Xiao1  +2 moreInstitutions (2)
Abstract: Natural fiber reinforced polymer composites (NFPCs) provide the customers with more alternatives in the material market due to their unique advantages. Poor fiber–matrix interfacial adhesion may, however, negatively affect the physical and mechanical properties of the resulting composites due to the surface incompatibility between hydrophilic natural fibers and non-polar polymers (thermoplastics and thermosets). A variety of silanes (mostly trialkoxysilanes) have been applied as coupling agents in the NFPCs to promote interfacial adhesion and improve the properties of composites. This paper reviews the recent progress in using silane coupling agents for NFPCs, summarizes the effective silane structures from the silane family, clarifies the interaction mechanisms between natural fibers and polymer matrices, and presents the effects of silane treatments on the mechanical and outdoor performance of the resulting composites.

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Topics: Silane (55%), Natural fiber (50%)

1,480 Citations


Open accessJournal ArticleDOI: 10.1038/S41467-018-03032-2
Jiuke Mu1, Gang Wang2, Hongping Yan3, Huayu Li2  +12 moreInstitutions (5)
Abstract: The ability to achieve simultaneous intrinsic deformation with fast response in commercially available materials that can safely contact skin continues to be an unresolved challenge for artificial actuating materials. Rather than using a microporous structure, here we show an ambient-driven actuator that takes advantage of inherent nanoscale molecular channels within a commercial perfluorosulfonic acid ionomer (PFSA) film, fabricated by simple solution processing to realize a rapid response, self-adaptive, and exceptionally stable actuation. Selective patterning of PFSA films on an inert soft substrate (polyethylene terephthalate film) facilitates the formation of a range of different geometries, including a 2D (two-dimensional) roll or 3D (three-dimensional) helical structure in response to vapor stimuli. Chemical modification of the surface allowed the development of a kirigami-inspired single-layer actuator for personal humidity and heat management through macroscale geometric design features, to afford a bilayer stimuli-responsive actuator with multicolor switching capability. Intrinsic deformation with fast response in commercially available materials that can safely contact skin continues to be a challenge for artificial actuating materials. Here the authors incorporate nanoscale molecular channels within perfluorosulfonic acid ionomer for self-adaptive and ambient-driven actuation.

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Topics: Actuator (53%)

1,348 Citations


Open accessJournal ArticleDOI: 10.1038/NATURE19100
Michael Wehner1, Michael Wehner2, Ryan L. Truby2, Ryan L. Truby1  +10 moreInstitutions (4)
25 Aug 2016-Nature
Abstract: An untethered, entirely soft robot is designed to operate autonomously by combining microfluidic logic and hydrogen peroxide as an on-board fuel supply. Soft robotics have so far necessarily included some 'hard' or metallic elements, in particular in the form of batteries or wiring, to connect them to an external power source. Additionally, external wiring tethering them to a power source places limits on the autonomy of such robots. Now Jennifer Lewis and colleagues have combined a 3D-printed soft polymeric robot with microfluidic logic and hydrogen peroxide as an onboard fuel to produce an eight-armed robot — an 'octobot' — that actuates its arms, without the incorporation of any hard structures. The hydrogen peroxide decomposes in the presence of a platinum catalyst to produce oxygen and a volumetric expansion that fills bladders embedded within the arms of the octobot. The design of the fuel reservoirs, microfluidic channels and vents to release the gas means that two sets of arms actuate cyclically. Soft robots possess many attributes that are difficult, if not impossible, to achieve with conventional robots composed of rigid materials1,2. Yet, despite recent advances, soft robots must still be tethered to hard robotic control systems and power sources3,4,5,6,7,8,9,10. New strategies for creating completely soft robots, including soft analogues of these crucial components, are needed to realize their full potential. Here we report the untethered operation of a robot composed solely of soft materials. The robot is controlled with microfluidic logic11 that autonomously regulates fluid flow and, hence, catalytic decomposition of an on-board monopropellant fuel supply. Gas generated from the fuel decomposition inflates fluidic networks downstream of the reaction sites, resulting in actuation12. The body and microfluidic logic of the robot are fabricated using moulding and soft lithography, respectively, and the pneumatic actuator networks, on-board fuel reservoirs and catalytic reaction chambers needed for movement are patterned within the body via a multi-material, embedded 3D printing technique13,14. The fluidic and elastomeric architectures required for function span several orders of magnitude from the microscale to the macroscale. Our integrated design and rapid fabrication approach enables the programmable assembly of multiple materials within this architecture, laying the foundation for completely soft, autonomous robots.

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Topics: Soft robotics (63%), Robot (52%), Soft lithography (51%)

1,012 Citations