Hierarchical folding of elastic membranes under biaxial compressive stress

Kim, Pilnam; Abkarian, Manouk; Stone, Howard A.

doi:10.1038/nmat3144

Cited by 227 publications

(254 citation statements)

References 31 publications

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“…1 present intriguing resemblances to patterns and other labyrinth structures reported in various compressed elastic systems (e.g., membranes, synthetic gels, and tissues) (12)(13)(14)(15). We propose here that this macroscopic morphology is a consequence of a buckling mechanical instability, as in other systems, and is triggered by growth in a confined space, which strains and hence stresses the pellicles.…”

supporting

confidence: 71%

Elasticity and wrinkled morphology of Bacillus subtilis pellicles

Trejo

Douarche

Bailleux

et al. 2013

Proc. Natl. Acad. Sci. U.S.A.

136

127

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Wrinkled morphology is a distinctive phenotype observed in mature biofilms produced by a great number of bacteria. Here we study the formation of macroscopic structures (wrinkles and folds) observed during the maturation of Bacillus subtilis pellicles in relation to their mechanical response. We show how the mechanical buckling instability can explain their formation. By performing simple tests, we highlight the role of confining geometry and growth in determining the symmetry of wrinkles. We also experimentally demonstrate that the pellicles are soft elastic materials for small deformations induced by a tensile device. The wrinkled structures are then described by using the equations of elastic plates, which include the growth process as a simple parameter representing biomass production. This growth controls buckling instability, which triggers the formation of wrinkles. We also describe how the structure of ripples is modified when capillary effects are dominant. Finally, the experiments performed on a mutant strain indicate that the presence of an extracellular matrix is required to maintain a connective and elastic pellicle.biofilm elasticity | biofilm growth | wrinkles formation B acterial biofilms most often refer to communities that self-assemble into a cohesive extracellular matrix on solid surfaces or as pellicles floating on top of liquids. Bacteria self-organize in a collective behavior, giving a large-scale coherence to the system. Biofilms thus represent a protected life mode allowing bacteria to survive in hostile environments and from where they can disperse to colonize new niches (1, 2). A primary characteristic of biofilm formation is the production of exopolymeric substances by some cells. These substances mostly consists of exopolysaccharides (EPS), a few specific proteins, and nucleic acids (3-5), but their exact composition depends on the strain of the bacterium and the type of nutrients present in the culture medium (6, 7). When studied in a laboratory, wild-type strains of Bacillus subtilis are known to produce floating pellicles of rich and complex multiscale architectures (8, 9). The vertical structures range from the local 50-μm-scale "fruiting bodies" (10) to the extended macroscopic patterns illustrated in Fig. 1. As recently suggested in ref. 11, multiscale roughness could play a role in increasing the defense capability of B. subtilis against vapor and liquid antimicrobial agents.This study centers on the physical forces acting on biofilm and determining their morphologies at the macroscopic scale. To proceed, we restrict our experimental approach to the simplified case where macroscopic pellicles stand on rich static media. We primarily focus on the pellicles formed by the wild-type strain NCIB 3610, but present some features measured on another wildtype strain DV1 to obtain a more complete picture of existing morphologies. Of course the phenotypes are even more complex in nature given the possible multistrain and species coassembly and the diversity of settings and environments.T...

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supporting

confidence: 71%

Elasticity and wrinkled morphology of Bacillus subtilis pellicles

Trejo

Douarche

Bailleux

et al. 2013

Proc. Natl. Acad. Sci. U.S.A.

136

127

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“…3b,dII, Movie 1). The pattern of wrinkles resembles those observed in bilayer systems induced by thermal expansion 41,42 , swelling 43,44 and ultraviolet or ion irradiation treatment 45,46 . As the applied electric field further rises, the valleys of the wrinkles are pinched down, forming a pattern of craters (Fig.…”

Section: Fabrication and Characterization Of The Emcr Elastomersupporting

confidence: 55%

Cephalopod-inspired design of electro-mechano-chemically responsive elastomers for on-demand fluorescent patterning

et al. 2014

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Cephalopods can display dazzling patterns of colours by selectively contracting muscles to reversibly activate chromatophores -pigment-containing cells under their skins. Inspired by this novel colouring strategy found in nature, we design an electro-mechano-chemically responsive elastomer system that can exhibit a wide variety of fluorescent patterns under the control of electric fields. We covalently couple a stretchable elastomer with mechanochromic molecules, which emit strong fluorescent signals if sufficiently deformed. We then use electric fields to induce various patterns of large deformation on the elastomer surface, which displays versatile fluorescent patterns including lines, circles and letters on demand. Theoretical models are further constructed to predict the electrically induced fluorescent patterns and to guide the design of this class of elastomers and devices. The material and method open promising avenues for creating flexible devices in soft/wet environments that combine deformation, colorimetric and fluorescent response with topological and chemical changes in response to a single remote signal.

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“…Larger applied strain forces these wrinkles merge into a single fold (Figure 1 d), while the surrounding gold fi lm is intact. [15][16][17] Sub-millimeter thick membranes of PU foam are produced using a simple bar coater setup ( Figure 2 a). A variety of two-component systems are available to produce PU foams, allowing for a wide range of foam densities and morphologies.…”

Section: Localization Of Folds and Cracks In Thin Metal Films Coated mentioning

confidence: 99%