Microfluidic control of droplet formation from stable emulsions formed by aqueous two-phase systems

Alyne G. Teixeira; Meng-Chiao Tsai; John P. Frampton

doi:10.1117/12.2297686

19 February 2018 Microfluidic control of droplet formation from stable emulsions formed by aqueous two-phase systems

Alyne G. Teixeira, Meng-Chiao Tsai, John P. Frampton

Proceedings Volume 10491, Microfluidics, BioMEMS, and Medical Microsystems XVI; 104910G (2018) https://doi.org/10.1117/12.2297686
Event: SPIE BiOS, 2018, San Francisco, California, United States

Abstract

Aqueous two-phase systems (ATPSs) form from the thermodynamic separation of two dissolved incompatible solutes, such as two polymers, a polymer and a salt, and a polymer and a surfactant. At most supercritical concentrations, ATPS emulsions can be formed by vigorous mixing. These emulsions typically settle into distinct layers in minutes to hours. However, it is also possible to choose ATPS compositions with extremely long settling times that resemble stable emulsions. Here, we generated stable emulsions from a polyethylene glycol (PEG)-dextran ATPS by selecting ATPS compositions at the extreme ends of the tie lines connecting the binodal curve delineating phase-separating compositions. Droplets of PEG in a continuous dextran phase did not coalesce appreciably over the course of several days when stored in a conical tube or syringe. However, upon exposure to laminar flow conditions in a microfluidic channel, droplets were observed to coalesce. Through microscopic characterization of droplet volume, an increase in droplet size and decrease in overall droplet number was observed as a function of channel distance, suggesting a progressive droplet merging phenomenon. This novel approach to control droplet size by encouraging coalescence of stable emulsions under laminar flow in a microfluidic channel enables the production of droplets ranging from fL to several pL, which may enable various future biotechnology applications.

Conference Presentation

Citation Download Citation

Alyne G. Teixeira, Meng-Chiao Tsai, and John P. Frampton "Microfluidic control of droplet formation from stable emulsions formed by aqueous two-phase systems ", Proc. SPIE 10491, Microfluidics, BioMEMS, and Medical Microsystems XVI, 104910G (19 February 2018); https://doi.org/10.1117/12.2297686

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