Breakup regimes of double emulsion droplets in a microfluidic Y-junction

The droplet breakup technology can effectively increase the generation throughput and adjust the droplets size, which has an important impact on the performance of the double emulsion droplets in medical, chemical, and other applications. This work presents an experimental study on the breakup regimes of double emulsion droplets after their on-chip generation. Five distinct breakup regimes are categorized according to the breakup times and the existence of the coupling effect during breakup process. Evolutions of the neck widths and thinning rates of both inner droplets and outer droplets are provided to discuss the dynamics of different regimes as well as different stages. In particular, the influences of the coupling effect on the interfacial evolution, collapsing mechanism, force analysis, and breakup critical condition are confirmed by comparisons with the results of single emulsion droplets.