Drop morphologies on flexible fibers: influence of elastocapillary effects

Sauret, Alban; Boulogne, François; Somszor, Katarzyna; Dressaire, Emilie; Stone, Howard A.

doi:10.1039/c6sm00921b

Cited by 13 publications

(11 citation statements)

References 51 publications

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“…DOI: 10.1103/PhysRevLett.118.198002 The physics of liquid droplets in contact with soft or deformable solids, elastocapillarity, is an active subject of research. Between capillary origami and wrinkling instabilities of thin films [1][2][3][4][5][6][7][8][9], the bending, coiling, and winding of slender structures [10][11][12][13][14][15][16], and elasticitymediated propulsion of droplets [17][18][19], there is no shortage of complexity, self-assembly, or beautiful examples of pattern formation in the field. In addition, some recent results have forced us to question familiar concepts of solid-liquid interactions.…”

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confidence: 99%

Liquid Droplets Act as “Compass Needles” for the Stresses in a Deformable Membrane

et al. 2017

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We examine the shape of droplets atop deformable thin elastomeric films prepared with an anisotropic tension. As the droplets generate a deformation in the taut film through capillary forces, they assume a shape that is elongated along the high tension direction. By measuring the contact line profile, the tension in the membrane can be completely determined. Minimal theoretical arguments lead to predictions for the droplet shape and membrane deformation that are in excellent agreement with the data. On the whole, the results demonstrate that droplets can be used as probes to map out the stress field in a membrane. DOI: 10.1103/PhysRevLett.118.198002 The physics of liquid droplets in contact with soft or deformable solids, elastocapillarity, is an active subject of research. Between capillary origami and wrinkling instabilities of thin films [1][2][3][4][5][6][7][8][9], the bending, coiling, and winding of slender structures [10][11][12][13][14][15][16], and elasticitymediated propulsion of droplets [17][18][19], there is no shortage of complexity, self-assembly, or beautiful examples of pattern formation in the field. In addition, some recent results have forced us to question familiar concepts of solid-liquid interactions. For instance, studies on the partial wetting of liquid drops on soft solids show that Young's law is applicable on length scales much larger than the bulk elastocapillary length γ=E, where γ is the liquid-air surface tension and E is the Young's modulus of the solid. However, on smaller length scales, the contact line reveals a wetting ridge set by a Neumann construction involving surface stresses [20][21][22][23][24][25][26].Partial wetting on deformable substrates may also be studied by employing a highly compliant geometry, such as a droplet on a thin freestanding film [27][28][29][30][31]. These studies have considered clamped films which are held taut and support a uniform and isotropic tension. As shown in Fig. 1(a), the Laplace pressure of the droplet creates a bulge in the film below it, in the shape of a spherical cap, which is of the same order in size as the droplet itself. The deformations generated may be orders of magnitude larger than the bulk elastocapillary length, because stretching of the membrane is the relevant mode of elasticity [28][29][30][31]. The contact line profile is determined by a Neumann construction, which incorporates both mechanical and interfacial tensions. This profile is characterized by the angles subtended by the liquid (θ d ) and bulge (θ b ) to the surrounding film [ Fig. 1(a)], which remains completely flat, i.e., the film's angle relative to the horizontal θ m ¼ 0. From the Neumann construction, these angles are set by two parameters: the Young's angle θ Y of the same solid supported on a rigid substrate and the ratio T in =γ, where T in is the total mechanical and interfacial tension acting inside the contact region of the membrane or drop system [31]. In the limit of infinite tension, the bulge vanishes and Young's law is recovered.In this stud...

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Liquid Droplets Act as “Compass Needles” for the Stresses in a Deformable Membrane

et al. 2017

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“…as straight parallel beams [16][17][18] pulled together by a force f acting per unit length of each galea (figure 4).…”

Section: Model Formulationmentioning

confidence: 99%

“…Therefore, when evaluating the capillary force acting on the galeae, as a first approximation, we can consider the galeae rsif.royalsocietypublishing.org J. R. Soc. Interface 15: 20180229 as straight parallel beams [16][17][18] pulled together by a force f acting per unit length of each galea (figure 4).…”

Section: Model Formulationmentioning

confidence: 99%

Self-assembly of the butterfly proboscis: the role of capillary forces

Zhang

Adler

Monaenkova

et al. 2018

J. R. Soc. Interface.

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The proboscis of butterflies and moths consists of two C-shaped fibres, the galeae, which are united after the insect emerges from the pupa. We observed that proboscis self-assembly is facilitated by discharge of saliva. In contrast with vertebrate saliva, butterfly saliva is not slimy and is an almost inviscid, water-like fluid. Butterfly saliva, therefore, cannot offer any viscoelastic adhesiveness. We hypothesized that capillary forces are responsible for helping butterflies and moths pull and hold their galeae together while uniting them mechanically. Theoretical analysis supported by X-ray micro-computed tomography on columnar liquid bridges suggests that both concave and convex liquid bridges are able to pull the galeae together. Theoretical and experimental analyses of capillary forces acting on natural and artificial proboscises show that these forces are sufficiently high to hold the galeae together.

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“…Spider thread windlasses are yet another example of elastocapillarity, the study of the interplay between fluid forces and elasticity of solids [3,4,5]. Former examples include the bending of elastic plates around liquid drops [6], the buckling of biofilaments inside liquid drops [7], and the wetting of fiber arrays [8,9,10] . Previous works on the capillary windlass effect have focused on parameter values for which gravity could be discarded, namely for very small systems where the weight of the drop is much smaller than capillary forces, see e.g.…”

Section: Introductionmentioning

confidence: 99%