Light-fuelled freestyle self-oscillators

Zeng, Hao; Lahikainen, Markus; Liu, Li; Ahmed, Zafar; Wani, Owies M.; Wang, Meng; Yang, Hong; Priimägi, Arri

doi:10.1038/s41467-019-13077-6

Cited by 166 publications

(152 citation statements)

References 40 publications

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“…Intersnap times range from 1.2 to 11.8 seconds, with an average time of 3.8 seconds. While oscillation due to self‐shadowing effects [ 37,42,57–59 ] and snapping between two bistable shapes [ 60,61 ] has been reported previously in nematic beams, cyclic oscillation via photoinduced snapping has only been reported in one other case, [ 62 ] to our knowledge. We hypothesize that this phenomenon is driven by self‐shadowing, where slight changes in the incident light intensity due to deformation toggles the equilibrium between buckling modes.…”

Section: Figurementioning

confidence: 95%

Blueprinting Photothermal Shape‐Morphing of Liquid Crystal Elastomers

et al. 2020

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studies have focused on programming desired 3D structures of soft materials such as shape-memory polymers [2,3] and gels [4][5][6][7] by introducing spatial variations in thermal expansion/contraction, swelling, or molecular order. [8] A particularly useful class of materials to achieve dynamic 2D to 3D shape transformations are liquid crystal elastomers (LCEs), where the coupling between the orientational ordering of polymerized mesogens and the conformation of a polymer backbone can be leveraged for large, anisotropic deformations that are dictated by the director field. [9,10] Using oriented surface alignment layers [11] or microchannels, [12] director orientation can be patterned with a resolution approaching 10 µm. [13] A subsequent reduction of nematic ordering, usually driven by heating, leads to local contraction along the director and expansion along the transverse directions, driving out-of-plane buckling into 3D shapes that are "blueprinted" by the pattern of director orientation. However, while geometric methods allow for the deduction of the necessary inplane director orientation field to generate a desired profile of Gaussian curvature, [14][15][16][17] there are a number of practical drawbacks to this approach. First, prescription of complex director fields requires significant processing, making high-throughput fabrication, and evaluation of designs challenging. Additionally, the surface alignment methods needed to specify director orientation with high spatial resolution are only amenable to certain chemistries due to the need for high mesogen content, and thus cannot be widely generalized to all LCE systems. For example, while classical LCE systems based on siloxanes, [18,19] as well as recently developed systems that rely on simple and efficient "click" chemistries, [20] offer attractive thermal and mechanical properties for shape-morphing systems, they typically only allow for alignment of the director field with coarse spatial resolution such as through application of shear stress [21][22][23] or magnetic fields. [24] To circumvent the need for a spatially varying director orientation, where the direction of deformation varies but the magnitude is constant, a potential alternative method to drive shape changes is to instead locally prescribe the magnitude of deformation within an otherwise homogeneous director field. While spatial variations in the extent of deformation have been widely employed for shape Liquid crystal elastomers (LCEs) are an attractive platform for dynamic shape-morphing due to their ability to rapidly undergo large deformations. While recent work has focused on patterning the director orientation field to achieve desired target shapes, this strategy cannot be generalized to material systems where high-resolution surface alignment is impractical. Instead of programming the local orientation of anisotropic deformation, an alternative strategy for prescribed shape-morphing by programming the magnitude of stretch ratio in a thin LCE sheet with constant director orientation is...

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Section: Figurementioning

confidence: 95%

Blueprinting Photothermal Shape‐Morphing of Liquid Crystal Elastomers

et al. 2020

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“…Zeng et al developed a light‐fueled self‐oscillator based on an LCN actuator that combines numerous oscillation modes (e.g., bending, twisting, and contraction–expansion) simultaneously by adjusting the excitation beam position. Furthermore, they presented the importance of time delay in the material response of the self‐oscillation 41. In 2019, Kageyama summarized the recent research on the development of self‐sustainable motion under steady light‐irradiated conditions by photoreactive molecules, such as azobenzene‐containing polymer and liquid crystal, and proposed that the coupling of nonlinear phenomena is important in promoting the self‐regulation of reaction in these materials 42.…”

Section: Introductionmentioning

confidence: 99%

An Autonomous Soft Actuator with Light‐Driven Self‐Sustained Wavelike Oscillation for Phototactic Self‐Locomotion and Power Generation

Yang

Chang

et al. 2020

Adv Funct Materials

119

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Mimicking the intelligence of biological organisms in artificial systems to design smart actuators that act autonomously in response to constant environmental stimuli is crucial to the construction of intelligent biomimetic robots and devices, but remains a great challenge. Here, a light-driven autonomous carbon-nanotube-based bimorph actuator is developed through an elaborate structural design. This curled droplet-shaped actuator can be simply driven by constant white light irradiation, self-propelled by a lightmechanical negative feedback loop created by light-driven actuation, time delay in the photothermal response along the actuator, and good elasticity from the curled structure, performing a continuously self-oscillating motion in a wavelike fashion, which mimics the human sit-up motion. Moreover, this autonomous self-oscillating motion can be further tuned by controlling the intensity and direction of the incident light. The autonomous actuator with continuous wavelike oscillating motion shows immense potential in light-driven biomimetic soft robots and optical-energy-harvesting devices. Furthermore, a self-locomotive artificial snake with phototaxis is constructed, which autonomously and continuously crawls toward the light source in a wave-propagating manner under constant light irradiation. This snake can be placed on a substrate made of triboelectric materials to realize continuous electric output when exposed to constant light illumination.

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“…Applying stimuli-responsive materials, oscillatory motions, and directional motions has also been reported [29][30][31][32][33][34][35][36][37][38][39][40][41]. Stimuli-responsive materials generally terminate their motion when the systems reach equilibrium.…”

Section: Research Aiming Mechanical Work With Energy Conversionmentioning

confidence: 96%

Robust Dynamics of Synthetic Molecular Systems as a Consequence of Broken Symmetry

Kageyama

2020

Symmetry

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The construction of molecular robot-like objects that imitate living things is an important challenge for current chemists. Such molecular devices are expected to perform their duties robustly to carry out mechanical motion, process information, and make independent decisions. Dissipative self-organization plays an essential role in meeting these purposes. To produce a micro-robot that can perform the above tasks autonomously as a single entity, a function generator is required. Although many elegant review articles featuring chemical devices that mimic biological mechanical functions have been published recently, the dissipative structure, which is the minimum requirement for mimicking these functions, has not been sufficiently discussed. This article aims to show clearly that dissipative self-organization is a phenomenon involving autonomy, robustness, mechanical functions, and energy transformation. Moreover, it reports the results of recent experiments with an autonomous light-driven molecular device that achieves all of these features. In addition, a chemical model of cell-amplification is also discussed to focus on the generation of hierarchical movement by dissipative self-organization. By reviewing this research, it may be perceived that mainstream approaches to synthetic chemistry have not always been appropriate. In summary, the author proposes that the integration of catalytic functions is a key issue for the creation of autonomous microarchitecture.

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Light-fuelled freestyle self-oscillators

Cited by 166 publications

References 40 publications

Blueprinting Photothermal Shape‐Morphing of Liquid Crystal Elastomers

Blueprinting Photothermal Shape‐Morphing of Liquid Crystal Elastomers

An Autonomous Soft Actuator with Light‐Driven Self‐Sustained Wavelike Oscillation for Phototactic Self‐Locomotion and Power Generation

Robust Dynamics of Synthetic Molecular Systems as a Consequence of Broken Symmetry

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