| Abstract
| - We show here both experimentally and theoretically that the formation of “coffee-ring” deposits observed atthe edge of drying water droplets requires not only a pinned contact line (Deegan et al. Nature1997, 389,827) but also suppression of Marangoni flow. For simple organic fluids, deposition actually occurs preferentiallyat the center of the droplet, due to a recirculatory flow driven by surface-tension gradients produced by thelatent heat of evaporation. The manipulation of this Marangoni flow in a drying droplet should allow one inprinciple to control and redirect evaporation-driven deposition and assembly of colloids and other materials.
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