Left-Handed or Right-Handed? Determinants of the Chirality of Helically Deformable Soft Actuators

Cheng, Mingxing; Li, Qingwei

doi:10.1089/soro.2021.0067

Cited by 5 publications

(5 citation statements)

References 45 publications

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“…The much thinner but stronger GO film can form optimal modulus match with the thicker BOPE film, which facilitates large and rapid morphing of the bimorph actuator (the optimal modulus match condition is: if d passive = d active , preferably E passive = E active ; and if d passive < d active , preferably E passive > E active ). 52 Through the above analyses, we conclude that it is precisely because of selecting the ultrathin GO film with high light absorbance (as the passive layer) and very thin BOPE film with a large CTE (as the active layer) that the photothermal actuator exhibits very fast and large-curvature deformations. If the thickness of the GO layer or BOPE layer is significantly increased, the deformation and response speed of the actuator will decline, which has been proved by experiments (Figures S4 and S5 and Movie S4).…”

Section: Key Role Of Materials Selection and Structuralmentioning

confidence: 85%

“…Third, Young’s modulus of the GO film (2.03 GPa) is much larger than that of BOPE (0.2–0.8 GPa) (Figure b). The much thinner but stronger GO film can form optimal modulus match with the thicker BOPE film, which facilitates large and rapid morphing of the bimorph actuator (the optimal modulus match condition is: if d passive = d active , preferably E passive = E active ; and if d passive < d active , preferably E passive > E active ) …”

Section: Resultsmentioning

confidence: 99%

“…The simulation results (Figure S6c−f) show that there is a linear correspondence between the helical angles θ helical and θ cut , and the morphing behaviors of this GO-UOPE actuator are consistent with the reported experiments and theoretical analyses. 11,14,46,52,53 For a more intuitive description, a circle divided into four quadrants or more sector regions was used to characterize the relationship between the same-chirality range (called the homochiral region) of the helical actuators and their cutting angles, i.e., "chirality vs θ cut ". The circle can be seen as a GO−PE bilayer composite film, and the strip actuators are cut out from the center of this circle and along different directions; the helical actuators with the same chirality are assigned to the same sector region, which is labeled by "L" or "R" (means left-handed and right-handed).…”

Section: Biaxial Anisotropy Of the Bope Film And Its Effect On The Ch...mentioning

confidence: 99%

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Ultrafast Photothermal Actuators with a Large Helical Curvature Based on Ultrathin GO and Biaxially Oriented PE Films

Yan

2022

ACS Appl. Mater. Interfaces

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In nature, there are some amazing superfast actuations (Venus flytrap) and large-curvature helical deformations (the awn of Erodium). Although many bionic actuators have been made (electrothermal, hygroscopic, photoinduced), most of their actuations are slow and small, not comparable to the wonderful ones in nature. Here, we report an ultrafast photothermal actuator with large-curvature curling based on an ultrathin graphene oxide (GO) and biaxially oriented polyethylene (BOPE) bilayer film (thickness ∼11 μm). By virtue of the fast temperature changing rate (peak: 900 °C s–1 during infrared heating and −1200 °C s–1 during cooling) and the great difference in the coefficient of thermal expansion of GO and BOPE layers, the actuator deforms rapidly and greatly. The maximum bending speed and curvature can reach 5300° s–1 and 22 cm–1, respectively, which are comparable to those of wonderful natural actuators and far exceed the performances of the reported artificial actuators. Different from ordinary helical actuators made of uniaxial anisotropic materials, our actuator is based on a typical biaxial anisotropic material of BOPE. However, the morphing behaviors of this type of actuator have not been reported before. So for the first time, we systematically studied this problem through experiments and simulations using the GO-BOPE actuator as a prototype and have drawn clear conclusions. In addition, functional GO-BOPE actuators capable of winding around and manipulating tiny objects were also designed and developed. We think this ultrafast large-curvature photothermal actuator will have wide application prospects in bionic actuations and dexterous robots.

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Section: Key Role Of Materials Selection and Structuralmentioning

confidence: 85%

Section: Resultsmentioning

confidence: 99%

Section: Biaxial Anisotropy Of the Bope Film And Its Effect On The Ch...mentioning

confidence: 99%

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Ultrafast Photothermal Actuators with a Large Helical Curvature Based on Ultrathin GO and Biaxially Oriented PE Films

Yan

2022

ACS Appl. Mater. Interfaces

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“…(Figure S7). Chen et al systematically studied the twisting mechanism of helical actuators . They found that material anisotropy plays a crucial role in the twisting of helical actuators.…”

Section: Resultsmentioning

confidence: 99%

Flexible Torsional Photoactuators Based on MXene–Carbon Nanotube–Paraffin Wax Films

Ding

Xiao

et al. 2022

ACS Appl. Mater. Interfaces

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A flexible actuator, which can convert external stimuli to mechanical motion, is an essential component of every soft robot and determines its performance. As a novel two-dimensional material, MXene has been used to fabricate flexible actuators due to its excellent physical properties. Although MXene-based actuators exhibit excellent actuation performance, their bending deformation is solely due to the in-plane isotropy of the MXene film, and an MXene torsional actuator has not been reported. This study presents a flexible torsional actuator based on an MXene−carbon nanotube (CNT)−paraffin wax (PW) film. In this actuator, the MXene thin film acts as a light absorption layer with wavelength selectivity, superaligned CNT provides structural anisotropy for the composite film, and PW acts as the active layer. The chirality and helical structure of the actuator could be tuned by the orientation of the CNT film. Such an actuator delivers excellent actuation performance, including high work density (∼1.2 J/cm 3 ), low triggering power (77 mW/cm 2 ), high rotational speed (320°/s), long lifetime (30,000 cycles), and wavelength selectivity. Inspired by vines, we used the torsional actuator as a spiral grabber, which lifted an object that weighs 20 times more than the actuator. The high-performance torsional actuator would be potentially used as a noncontact sensor, rotary motor, and grabbing tool in the soft robot system.

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“…Ansys, Comsol and Abaqus are three kinds of widely used commercial FEA tools/software in the fields of engineering and academic research. Many researchers employed Ansys [20][21][22], Comsol [23][24][25][26][27] and Abaqus [28][29][30][31][32][33][34][35][36][37] to study the properties of novel materials and simulate morphing behaviors of various actuators. However, the biaxially anisotropic Young's modulus and CTE of the BAPs cannot be well described in all these FEA software by defining material properties.…”

Section: The Methodology Of Feamentioning

confidence: 99%

The modeling method and simulation study on the biaxially anisotropic polymer films

Li,

2024

Smart Mater. Struct.

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Biaxially anisotropic polymer (BAP) films are very common materials, usually prepared by stretching linear polymers along two orthogonal directions in sequence. Most molecular chains of BAPs are oriented in the two stretching directions with a crossed arrangement, leading to unique properties of BAP films. However, the theoretical and simulation studies on BAPs and BAP-based devices are few until now. Here, we developed entity modeling methods to successfully simulate actual BAPs: through constructing the model of crossed rebars embedded in matrix, which respectively imitate crossed molecular chains and inter-chain van der Waals interactions, the mechanical properties of the BAP films/strips can be reproduced. Different from uniaxially anisotropic polymers, the longitudinal Young’ moduli of BAP strips have two maxima in 0°/90° directions, and their coefficients of thermal expansion (CTEs) also have two maxima in ±45° directions. By introducing asymmetry, the BAP film model becomes from symmetric to moderately asymmetric and then to highly asymmetric: the ratio of two modulus maxima (in 0°/90°) increases (from 1 to 1.13, then to 1.22), and the directions of maximum CTEs also change (from ±45° to ±35°, then to ±27°), making the simulated BAP films closer to reality. Moreover, we systematically studied the helical morphing behaviors of the BAP-based bimorph actuator by finite element simulations. The chirality of this strip actuator is reversed four times, while its cutting angle changes within 180°. Besides, as the asymmetry of BAP film increases, the angle of chirality reversion of the BAP-based actuators changes from ±45° to ±60°, then to ±70°.

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Left-Handed or Right-Handed? Determinants of the Chirality of Helically Deformable Soft Actuators

Cited by 5 publications

References 45 publications

Ultrafast Photothermal Actuators with a Large Helical Curvature Based on Ultrathin GO and Biaxially Oriented PE Films

Ultrafast Photothermal Actuators with a Large Helical Curvature Based on Ultrathin GO and Biaxially Oriented PE Films

Flexible Torsional Photoactuators Based on MXene–Carbon Nanotube–Paraffin Wax Films

The modeling method and simulation study on the biaxially anisotropic polymer films

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