Microdroplets: Drop Splitting

When performing a biological assay with a reagent, it is often necessary to divide the reagent into smaller portions that can then be reacted with different compounds. In droplet-based microfluidics, the module that performs this function is a droplet splitter. To split a drop, the drop is flowed into a channel that bifurcates into two channels; provided the hydrodynamic resistances of the two paths are equal and the flow rates sufficiently high, the drop will be bisected into two equal portions, as illustrated in this movie:

In most instances, splitting homogeneous single emulsions is all that's necessary; however, there are instances in which droplets containing smaller drops must also be split. These kinds of drops could be the product of an assay in which encapsulated microbes secrete an oily substance, like a biodiesel, which would form a droplet beside the microbe. Such multiple emulsions, or "emulsions within emulsions" can also be bisected using splitting devices, as shown in this movie: