Controlling Droplets with Geometry

Fluid droplets can both drive and be driven by shape changes in soft materials. The interplay between elasticity and capillarity leads to diverse natural phenomena — from the buckling and closure of airway tubes in lungs to the spooling and packing of spider silk by droplets. We investigate the influence of geometry on the behavior of droplets. We find ways to manipulate drops by changing the geometrical parameters of the underlying soft substrate. Understanding these interactions lets us control tiny amounts of fluid and opens up the possibility of using metamaterials to maneuver liquids and vice versa.