Generalised insights in droplet formation at T-junctions through statistical analysis

Though much experimental work has been done on droplet formation in microfluidic T-junctions, the field is fragmented due to differences in channel dimensions, flow rates, and materials used. The same is true for models, which describe a limited range of the droplet formation spectrum, due to obvious boundary conditions. In this paper, we tried to unify the available data into a more general model using statistical analysis. This approach was chosen because of its accessibility and ease of use for unbiased analysis of available data. We found that data from various literature sources, and therefore different regimes, were described with a two-step model, which distinguishes between a droplet growth and a droplet detachment phase. The two-step model was found statistically valid over the whole range of observed droplet shapes (viz plugs, discs, or drops) and encompassed all systems and sources. Channel dimensions were found to determine droplet growth, while both continuous and disperse phase flow rate govern the subsequent time needed for detachment. By using a statistical approach, we were able to generalise data available on T-junctions into general rules of behaviour.