(38f) Dynamics and Stability of Arrays of Connected Droplets: Coarsening by Capillarity

Precise manipulation of pico- and femto-liter droplets is an enabling step in a broad range of micro-fluidic technologies. Coarsening by capillarity occurs when surface area minimization dominates the behavior of an array of connected droplets. Droplets scavenge volume from one another based on pressure differences proportional to the surface tension and arising from curvature differences. Suppressing volume-scavenging and consequent coarsening is a key challenge to manipulating droplets connected by a network of flow paths. The tendency of system volume to end up in a single ?winner' droplet is easy to understand. More difficult is to predict which droplet will be the winner, something that depends on the network connectivity. Predicting the winner among N contenders is framed as a problem of identifying basins-of-attractions for an N-dimensional nonlinear dynamical system. In this talk, we illustrate the phenomenon, demonstrate that predicting the winner is not trivial and then show how to successfully pick the winner. We end by comparing predictions of analysis to results of simulations and illustrate with experiments on a controllable wet-adhesion device.