a, Complex emulsion fabrication. b, Above Tc, hexane and perfluorohexane are miscible and emulsified in aqueous 0.1% Zonyl (top left). Below Tc, hexane and perfluorohexane phases separate to create a hexane-in-perfluorohexane-in-water (H/F/W) double emulsion (bottom right). Hexane is dyed red. Scale bar, 200 μm. c, Emulsions of uniform composition made by bulk emulsification (such as shaking). Scale bar, 100 μm. d, Lateral confocal cross-section of H/F/W double-emulsion droplets. Hydrocarbon-soluble Nile Red dye (green) selectively extracts into hexane. Rhodamine B dyes the aqueous phase (red). Scale bar, 100 μm. Monodisperse droplets in b and d were made using a microcapillary device.