Droplet Microfluidics: Mixing in Merged Droplets - EE DRAFT

Background

Along with a number of benefits that arise from working in the microscale, including working in a laminar flow regime, there are some novel problems. Two such problems are sample dispersion and mixing. There have been many microfluidic devices designed to improve mixing, and similar efforts to control dispersion. One of the most effective means of controlling dispersion is to isolate the aqueous phase in an immiscible carrier fluid. These droplets, or plugs, can be generated in uniform size, and moved through microfluidic channels with relative ease, and the solute concentration will remain unchanged within the droplet. For many applications, however, we need to combine multiple reagents, and often in a time-sensitive manner, with complete mixing. In these cases, it is useful to create droplets that contain multiple reagents, or merge droplets containing reactants. For a discussion on merging of droplets please refer to Merging Droplets and T-Junctions, above.

Once droplets have been merged within a microfluidic channel, the rate at which their components mix within the merged droplets may need to be controlled, specifically in cases where rapid mixing is required. Some examples of where rapid mixing is important include explorations of reaction kinetics or the study of thermal events resulting from molecular interactions.

Approaches

Dummann 2003 simple plugs and mass transfer effects, Tice 2003 - twirling Ca wf inorganic dyes for visualization, song 2003 agnew rapid mixing no dispersion ms timescale, wang 2015 serpentine

Viscosity differences within droplets and the effects on mixing

Tice 2004

Cases in literature

ms kinetics Helen Song JACS 2003

optical calorimeter Recht Martini Chamoun

Commercial applications and solutions

Micronit

Dolomite