Figure 3
Mechanism for highly efficient water capture. (a) Adhesion force measurement of a water droplet (1 μl) on a pappus. The ΔF=9.75±0.9 μN stretch force is smaller than the adhesive force of the pappus to water, indicating that the pappus is highly adhesive to water. The successive images of a water droplet interacting with a pappus are denoted by (a1–a3). Residual water (a4) remained on the pappus after water droplet detachment. (b) Digital images of the pulvinus before (b1) and after (b2) interaction with water. The water becomes tightly pinned to the pulvinus, indicating the high adhesiveness of the pulvinus to water. (c) A two-dimensional (2D) model describing the deformation of the pappus because of interaction of the elasticity of the pappus and the adhesion force to the water arising from the surface tension and the hydrostatic pressure. (d) Two radially arranged glass fibers with the open angle of 176° interacting with water to encapsulate a relatively large water membrane. After interacting with the water interface (d1 and d2), the radial glass fibers adhered a water membrane (d3) when drawn upwards, and totally encapsulated the large water membrane (d4) when left the water interface.
