Microflow behavior of solvent-rich droplets in coaxial channels

We experimentally study the microfluidic behavior of ternary fluid systems made of two immiscible fluids and a miscible solvent. We examine, in particular, the multiphase flow situation where the solvent is mixed in the dispersed phase and we investigate the two complementary configurations of water-in-oil and oil-in-water dispersions at short time scales. Flow maps are delineated over a wide range of flow rates and solvent concentrations and we show a variety of intriguing interfacial flow phenomena, such as typical dripping, jetting, and core-annular flows at low solvent concentration and unique regimes, such as dynamic wetting, spontaneous emulsification, and tip streaming at high concentration. Methods based on flow pattern analysis are developed to elucidate the relationship between complex flow morphology and fluid properties of multiphase materials in confined microsystems.