Strain-driven self-rolling mechanism for anomalous coiling of multilayer nanohelices

Lu, Dai; Shen, Wei

doi:10.1063/1.3267866

Cited by 9 publications

(8 citation statements)

References 33 publications

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“…We note that experimental validation of the theory has also been demonstrated for the more general case in which both sides of the elastic strip are bonded to differently oriented pre-stretched layers of latex rubber (Chen et al 2011) It is important to emphasize that helicity in these systems arises from mechanical anisotropy. Such anisotropy may originate from elastic anisotropy due to molecular tilt or chiral interactions (Selinger et al 2004) , or mechanical anisotropy in surface/external stresses, residual strains and elastic properties (Zhang et al 2005;Wang et al 2008;Dai and Shen 2009;Pokroy et al 2009) . In molecular dynamics simulations, anisotropy can also arise from the asymmetry in the direction along which periodic boundary condition is applied (Lee et al 2011) .…”

Section: Experimental Validation and Discussionmentioning

confidence: 99%

Continuum Elasticity Theory Approach for Spontaneous Bending and Twisting of Ribbons Induced by Mechanical Anisotropy

Chen,

Majidi,

Srolovitz

et al. 2012

Preprint

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Helical ribbons arise in many biological and engineered systems, often driven by anisotropic surface stress, residual strain, and geometric or elastic mismatch between layers of a laminated composite. A full mathematical analysis is developed to analytically predict the equilibrium deformed helical shape of an initially flat, straight ribbon, with prescribed magnitudes and orientations of the principal curvatures when subjected to arbitrary surface stress and/or internal residual strain distribution. The helix angle, radius, axis and chirality of the deformed helical ribbons are predicted with a comprehensive, three-dimensional model that incorporates elasticity, differential geometry, and variational principles. In general, the mechanical anisotropy (e.g., in surface/external stress, residual strain or elastic modulus) will lead to spontaneous, three-dimensional helical deformations. Ring shapes are formed when the principle axes of deformation coincide with the geometric axes of the ribbon. The transition from cylindrical helical ribbons to purely twisted ribbons, or tubular structures is controlled by tuning relevant geometric parameters. Analytic, closed-form predictions of the ribbon shapes are validated with simple, table-top experiments. This theoretical approach represent a tool to inform the design of materials and systems in order to achieve desired helical geometries on demand.

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Section: Experimental Validation and Discussionmentioning

confidence: 99%

Continuum Elasticity Theory Approach for Spontaneous Bending and Twisting of Ribbons Induced by Mechanical Anisotropy

Chen,

Majidi,

Srolovitz

et al. 2012

Preprint

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show abstract

“…In addition, the estimation of radii of the rolledup helix on Si(111) surface is conducted by an analytical model based on Cosserat curve theory. [36][37][38] 2 Results and discussion Fig. 1(a) shows an SEM image of the rolled-up SiGe/Si/Cr stripes obtained from the clock-like pattern.…”

Section: Introductionmentioning

confidence: 99%

“…To analyze the radius of the rolled-up structure, we assume that a strained ribbon with a width w and thickness t (w > t) detaches from the substrate and releases the internal strain to form a helix H with a radius a and a pitch b. Based on the Cosserat curve model the geometry parameters of the helix H as well as the force s, torque m along the helical axis can be expressed as: 38 a ¼ 1…”

Section: Introductionmentioning

confidence: 99%

Directional scrolling of SiGe/Si/Cr nanoribbon on Si(111) surfaces controlled by two-fold rotational symmetry underetching

Zhang

2013

Nanoscale

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The controllable fabrication of self-scrolling SiGe/Si/Cr helical nanoribbons on Si(111) substrates is investigated. The initial lateral etching profile of the Si(111) substrates shows a 2-fold rotational symmetry using 4% ammonia solution, which provides guidance for initial scrolling of one-end-fixed nanoribbons to form helical structures. The chirality of the SiGe/Si/Cr helices with isotropic Young's moduli is governed by the anisotropic underetching in the initial stage, which can be precisely judged, as the orientation of the ribbon is predesigned. Furthermore, the helicity angle and radius of the formed helices are investigated by the lateral etching behavior and Cosserat curve theory of the Si(111) substrates, respectively, which are consistent with the experimental data. The present work provides the scrolling rule of nanoribbons with an isotropic Young's modulus and anisotropic underetching in the formation of micro-/nanohelices.

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“…14). Dai and Shen subsequently used a Cosserat rod theory to interpret this abnormal phenomenon by also considering the increasing edge effects as the width became larger [148]. More generally, a helical ribbon bends around two principal axes, r 1 and r 2 , with principal curvatures, and , as shown in Fig.…”

Section: B Mechanical Self-assembly Of Helical Ribbons: Microfabricamentioning

confidence: 99%

Mechanical Self-Assembly of a Strain-Engineered Flexible Layer: Wrinkling, Rolling, and Twisting

et al. 2016

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Self-shaping of curved structures, especially those involving flexible thin layers, has attracted increasing attention because of their broad potential applications in e.g. nanoelectromechanical/micro-electromechanical systems (NEMS/MEMS), sensors, artificial skins, stretchable electronics, robotics, and drug delivery. Here, we provide an overview of recent experimental, theoretical, and computational studies on the mechanical self-assembly of strain-engineered thin layers, with an emphasis on systems in which the competition between bending and stretching energy gives rise to a variety of deformations, such as wrinkling, rolling, and twisting. We address the principle of mechanical instabilities, which is often manifested in wrinkling or multistability of strain-engineered thin layers. The principles of shape selection and transition in helical ribbons are also systematically examined. We hope that a more comprehensive understanding of the mechanical principles underlying these rich phenomena can foster the development of new techniques for manufacturing functional threedimensional structures on demand for a broad spectrum of engineering applications.2

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Strain-driven self-rolling mechanism for anomalous coiling of multilayer nanohelices

Cited by 9 publications

References 33 publications

Continuum Elasticity Theory Approach for Spontaneous Bending and Twisting of Ribbons Induced by Mechanical Anisotropy

Continuum Elasticity Theory Approach for Spontaneous Bending and Twisting of Ribbons Induced by Mechanical Anisotropy

Directional scrolling of SiGe/Si/Cr nanoribbon on Si(111) surfaces controlled by two-fold rotational symmetry underetching

Mechanical Self-Assembly of a Strain-Engineered Flexible Layer: Wrinkling, Rolling, and Twisting

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