Fig. 4.

Self-folding droplet networks. (A) Schematic of two droplets of different osmolarities joined by a lipid bilayer. The flow of water through the bilayer causes the droplets to swell or shrink. (B) Schematic of a droplet network that comprises two strips of droplets of different osmolarities. The transfer of water between the droplets induces an overall deformation of the network. (C) Photographs of a rectangular network folding into a circle over ~3 h. The orange and blue droplets initially contain 250 mM KCl and 16 mM KCl, respectively. Scale bar, 250 μm. (D) Photographs of a flower-shaped network folding spontaneously into a hollow sphere. The orange and blue droplets initially contain 80 mM KCl and 8 mM KCl, respectively. The photographs cover a period of 8 h. Scale bar, 200 μm. (E) Frames from a folding simulation of a network with a similar initial geometry to the network in (D). Blue and red represent the lowest and highest initial osmolarities, respectively, and white indicates the average of the two.