Spontaneous emulsification of microfluidic droplets

We experimentally study the dynamics of spontaneous emulsification using microfluidic droplets made of a mixture of oil and solvent in a hydrophilic continuous phase. The spontaneous nucleation and subsequent coalescence of miniature drops within microfluidic droplets is investigated at different time-scales to better characterize capillary and mass transfer phenomena. We examine, in particular, the evolution of turbidity as a function of flow rates and fluid properties during the formation of microfluidic droplets in coaxial microdevices. We delineate the cross-over between diffusive and non-diffusive flow regimes and analyze the evolution of periodic microfluidic flow patterns based on solvent concentration. This work shows the possibility to manipulate the microflow behavior of ternary mixtures at ultralow interfacial tension.