Highly uniform micro-cavity arrays in flexible elastomer film

Uniform hexagonal arrays of spherical micro-cavities are created in an elastomer film in a one-step process. The cavities are the imprints of water droplets condensed from saturated vapor in a heated closed container. The saturated vapor arises from evaporation of water from a reservoir within the container. Competition between droplet growth and curing of the elastomer film determines the structure of the resulting pattern.