Controllable rotational inversion in nanostructures with dual chirality

Lu, Dai; Zhu, Ka-Di; Shen, Wei; Huang, Xishi; Zhang, Li; Goriely, Alain

doi:10.1039/c7nr09035h

Cited by 12 publications

(10 citation statements)

References 33 publications

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“…The dual chirality of self-wound wires with perversions have the potential to cancel this rotation, and such coils could expand the Hookean response that is ideal for stretchable sensors and "twistless spring" devices. [29] We confirm that the elongation of gelatin-AF/Fe 3 O 4 coil is highly sensitive to B intensity, even when immersed in water. Deviations from Equations (2) and (3), such as the additive constant, are attributed to gravity-induced coil elongation and buoyancy, because the experiments are performed vertically in water.…”

supporting

confidence: 72%

Self‐Winding Gelatin–Amyloid Wires for Soft Actuators and Sensors

et al. 2020

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microfibrils are embedded. [10] These structures, which resemble artificial fiber-reinforced composites, deform largely along the alignment of the microfibrils, and deformation perpendicular to this reinforcement occurs less strongly. [11] This differential deformation is then transferred to macroscopic shape-shifting mechanisms such as self-winding. Self-winding is a competition between bending and twisting, which often stems from a need to release potential energy present in surface stresses, misfit strains, residual strains, thermal stresses, differential growth, shrinkage, or swelling. [12] Understanding these mechanisms is of fundamental importance to gaining insights into the design and application of helical shapes. Various works have been inspired by biological principles to generate self-winding as a response to external stimuli; however, most of them focus on the design of bilayers with mismatching properties. [11,13-15] Usually, the precursor is a flat ribbon or a straight rod formed by two layers with differential responses to stimuli. [3,16] However, simple formulation and production methods that mimic the spontaneous nature of self-coiling are still lacking. Here, we present a new fabrication approach that originates spontaneously self-winding wires upon their differential swelling in water. We apply biomimetic concepts to designing gelatin wires that are reinforced by amyloid fibrils (AFs) following principles similar to fiber-reinforced composites. Our fabrication dry-spins a single phase, thus bypassing the need for precise bilayer design and offering an easy, scalable, and sustainable alternative to more complex material designs. We employ β-lactoglobulin (BLG) to form AFs because of its rich and chiral structure. Although amyloid fibrils have promising properties, they alone cannot be processed as biopolymers because of their high rigidity and low plasticity. Therefore, we combine the plasticity of gelatin with the rigidity and versatile functionalization of AFs to produce wires that spontaneously self-wind in water. We investigate the origins of self-winding mechanisms by modeling the relative contributions of twisting and winding to the free energy. Finally, we explore the potential applications of such self-wound wires in sensors and actuators and complement our experimental results with theoretical interpretations. The wires disclosed here are, to the best of our knowledge, the first example of a system that is capable of performing as both actuator and sensor, produced entirely

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confidence: 72%

Self‐Winding Gelatin–Amyloid Wires for Soft Actuators and Sensors

et al. 2020

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“…For a helix with one perversion locating at its center, it can be treated as two helical springs connecting to each other via the perversion. During the loading process, the connecting ‘end’ of these two helical springs can freely rotate since the perversion can rotate around the helix’s axis, and hence this dual-chirality helical shape can retain the linear force-extension response in a larger elongation region compared to the common helical spring [ 106 ]. Therefore, the study on the formation of helical structures mimicking the tendril’s coiling is not only important in understanding the plant’s morphology, but will also be beneficial to the engineering applications such as nanomechanical systems.…”

Section: Helical Structures Mimicking Tendril’s Coilingmentioning

confidence: 99%

“…The higher

is, the lower

will be. Dai et al [ 106 ] employed the extensible rod theory to investigate the effect of

on the rotatory motion of a helix with one perversion during the pulling process. A phase diagram separating the over-winding and un-winding regimes is presented in terms of the axial elongation and

( Figure 15 b).…”

Section: Helical Structures Mimicking Tendril’s Coilingmentioning

confidence: 99%

“…A perverted-spring with over-winding behavior will first become softened and then get stiffened in the large extension region compared to the common helical spring [ 13 ]. Dai et al [ 106 ] investigated the effect of

on the mechanical behavior of a helix with one perversion based on the experiments of the scrolled SiGe/Si/Cr nanohelix, and they observed that the binormal cross section (

) is a better choice to provide linear elastic response of the helix with dual-chirality than the normal cross section (

) ( Figure 15 c).…”

Section: Helical Structures Mimicking Tendril’s Coilingmentioning

confidence: 99%

“…( a ) The tendril exhibits over-winding initially and then unwinds itself during pulling; ( b ) The phase diagram separating the unwinding and over-winding regimes in terms of elongation and

; ( c ) The Hooke’s constant of a scrolled SiGe/Si/Cr nanohelix with the normal or binormal cross-section under extension. ( a – c ) are from [ 106 ], reproduced with permission from The Royal Society of Chemistry.…”

Section: Figurementioning

confidence: 99%

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Helical Structures Mimicking Chiral Seedpod Opening and Tendril Coiling

Wan

Jin

Trase

et al. 2018

Sensors

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Helical structures are ubiquitous in natural and engineered systems across multiple length scales. Examples include DNA molecules, plants’ tendrils, sea snails’ shells, and spiral nanoribbons. Although this symmetry-breaking shape has shown excellent performance in elastic springs or propulsion generation in a low-Reynolds-number environment, a general principle to produce a helical structure with programmable geometry regardless of length scales is still in demand. In recent years, inspired by the chiral opening of Bauhinia variegata’s seedpod and the coiling of plant’s tendril, researchers have made significant breakthroughs in synthesizing state-of-the-art 3D helical structures through creating intrinsic curvatures in 2D rod-like or ribbon-like precursors. The intrinsic curvature results from the differential response to a variety of external stimuli of functional materials, such as hydrogels, liquid crystal elastomers, and shape memory polymers. In this review, we give a brief overview of the shape transformation mechanisms of these two plant’s structures and then review recent progress in the fabrication of biomimetic helical structures that are categorized by the stimuli-responsive materials involved. By providing this survey on important recent advances along with our perspectives, we hope to solicit new inspirations and insights on the development and fabrication of helical structures, as well as the future development of interdisciplinary research at the interface of physics, engineering, and biology.

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