Microfluidic Generation of High-Viscosity Droplets by Surface-Controlled Breakup of Segment Flow.

Fluids containing high concentration polymers, sols, nanoparticles, etc., usually have high viscosities, and high-viscosity fluids are difficult to be encapsulated into uniform droplets. Here we report a surface-controlled breakup method to generate droplets directly from various aqueous and nonaqueous fluids with viscosities of 1.0 to 11.9 Pa s and a dispersed-to-continuous viscosity ratio up to 1000, whereas the volume fraction of droplets up to 50% can be achieved. It provides a straightforward method to encapsulate high viscosity fluids, in a well-controlled manner in the rapid developing droplet-based applications, including materials synthesis, drug delivery, cell assay, bioengineering, etc.