title: Contact line deposits in an evaporating drop
abstract: Solids dispersed in a drying drop will migrate to the edge of the drop and form a solid ring. This phenomenon produces ringlike stains and occurs for a wide range of surfaces, solvents, and solutes. Here we show that the migration is caused by an outward flow within the drop that is driven by the loss of solvent by evaporation and geometrical constraint that the drop maintain an equilibrium droplet shape with a fixed boundary. We describe a theory that predicts the flow velocity, the rate of growth of the ring, and the distribution of solute within the drop. These predictions are compared with our experimental results.
authors.affiliation: James Franck Institute, 5640 South Ellis Avenue, Chicago, Illinois 60637, USA.
authors.initials: RD
authors.lastname: Deegan
authors.initials: O
authors.lastname: Bakajin
authors.initials: TF
authors.lastname: Dupont
authors.initials: G
authors.lastname: Huber
authors.initials: SR
authors.lastname: Nagel
authors.initials: TA
authors.lastname: Witten