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Stretchable surfaces with programmable 3D texture morphing for synthetic camouflaging skins

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Science  13 Oct 2017:
Vol. 358, Issue 6360, pp. 210-214
DOI: 10.1126/science.aan5627
  • Fig. 1 Inspiration for and description of CCOARSE.

    (A) A conical papilla (~4 mm high) in Octopus rubescens that dynamically extends or retracts in ~220 ms. This small species has numerous skin papillae that provide exceptional camouflage in shallow kelp habitats in central California. Frame grabs are from video of a live animal [video: R. Hanlon]. (B) An inflated silicone membrane showing the principal strains and resulting deformation of points on the undeformed planar membrane. The radial and circumferential strains displace the points vertically (v) and radially (r) , but not along θ. (C) An inextensible nonwoven mesh embedded in the silicone membrane constrains the circumferential strain, resulting in vertical displacement based on the radial strain. (D) Fabrication of the mesh-silicone membrane. Silicone is poured into a mold. Mesh is embedded, laser cut, and removed, and then the silicone is cured. A topcoat of silicone is added to fill voids and improve mesh adhesion. (E) A tenstile testing specimen section with horizontal layers of mesh and LS/L silcione length fraction. (F) Stress-strain measurements for specimens with multiple silicone length fractions. (G) Relationship between the composite membrane strain and silicone length fraction taken from (F) at 50-, 100-, and 150-kPa membrane stress states. This information maps the mesh design in a silicone-mesh composite membrane to a target 3D shape.

  • Fig. 2 Design and displacement of axisymmetric membranes with positive, zero, and negative Gaussian curvature target shapes.

    (A) The target shape displacement and composite radial strain versus radial position required to achieve that shape, discretized into 10 segments. (B) The radial mesh patterns mapped from the composite radial strain. Black represents mesh, and gray is silicone. L is the length between vertical gray lines in (A). The resulting inflated shapes and Gaussian curvatures are shown below the mesh patterns. (C) The axisymmetric side profile of the inflated membranes. The solid colored lines are the mean, minimum, and maximum displacement of eight samples tested for each curvature. The highlighted regions behind the target shapes are displacements within 10% of the target shape (solid black line). The dashed lines show the dynamic range of shapes for a representative sample inflated at decreasing pressures.

  • Fig. 3 Design and displacement of membranes with nonsymmetric and hierarchical target shapes.

    (A) A membrane with nonsymmetric target displacement (blue line) designed after a river stone silhouette (dashed line). (B) An inflated membrane with second-order hierarchy that combines negative, zero, and positive Gaussian curvature surfaces. (C) Adding suspended mesh supports to the membrane underside improves the shape fidelity of high-aspect-ratio mesh patterns by preventing bending of the individual mesh strips. The inflated membrane has two elliptical membranes with 16 mm initial width across the minor axis. The right membrane has suspended mesh supports.

  • Fig. 4 Membranes programmed to deform into biomimetic shapes by combining axisymmetric, nonsymmetric, and hierarchical shape transformations.

    (A) A 22- by 22-cm membrane programmed to inflate into nonsymmetric and hierarchical stone shapes. Natural river stones with the same color encircle the membrane. The mesh design is shown on the bottom. (B) A membrane programmed to inflate into the shape of a G. amethorum plant. The leaves are arranged in a spiral around a center point and use suspended mesh supports to maintain the high-aspect-ratio mesh patterns. (C) Digital photograph of a G. amethorum plant. (D) The Gaussian curvatures of the inflated and deflated membranes. (E) A topographical map with stretchable electroluminescent display that inflated to the landscape’s true 3D shape by use of CCOARSE. The black contour lines and color-coded regions represent areas of equal elevation.

Supplementary Materials

  • Stretchable surfaces with programmable 3D texture morphing for synthetic camouflaging skins

    J. H. Pikul, S. Li, H. Bai, R. T. Hanlon, I. Cohen, R. F. Shepherd

    Materials/Methods, Supplementary Text, Tables, Figures, and/or References

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    • Materials and Methods 
    • Supplementary Text 
    • Figs. S1 to S4

    Images, Video, and Other Media

    Movie S1
    Papillae Expression by Giant Cuttlefish. © Roger Hanlon 2012
    Movie S2
    Inflated negative Gaussian curvature membrane
    Movie S3
    Inflated negative Gaussian curvature membrane cycled at 1 Hz
    Movie S4
    Inflated hierarchical membrane
    Movie S5
    Inflated stone camouflage membrane
    Movie S6
    Inflated stone camouflage membrane with large stone
    Movie S7
    Inflated Graptoveria amethorum plant at 2x speed
    Movie S8
    Inflated topographical map with electroluminescent display

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