Capillary Origami: Spontaneous Wrapping of a Droplet with an Elastic Sheet

The interaction between elasticity and capillarity is used to produce three-dimensional structures through the wrapping of a liquid droplet by a planar sheet. The final encapsulated 3D shape is controlled by tailoring the initial geometry of the flat membrane. Balancing interfacial energy with elastic bending energy provides a critical length scale below which encapsulation cannot occur, which is verified experimentally. This length is found to depend on the thickness as h^3/2, a scaling favorable to miniaturization which suggests a new way of mass production of 3D micro- or nanoscale objects.