Electrocoalescence of paired droplets encapsulated in double-emulsion drops.

We utilize an ac electric field to trigger the on-demand fusion of two aqueous cores inside water-in-oil-in-water (W/O/W) double-emulsion drops. We attribute the coalescence phenomenon to field-induced structural polarization and breakdown of the stress balance at interfaces. This method provides not only accurate control over the reaction time of coalescence but also protection of the reaction from cross contamination.