Gas-assisted microfluidic step-emulsification for generating micron- and submicron-sized droplets

Biao Huang, Xinjin Ge, Boris Y. Rubinstein, Xianchun Chen, Lu Wang, Huiying Xie, Alexander M. Leshansky*, Zhenzhen Li*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

5 Citations (Scopus)

Abstract

Micron- and submicron-sized droplets have extensive applications in biomedical diagnosis and drug delivery. Moreover, accurate high-throughput analysis requires a uniform droplet size distribution and high production rates. Although the previously reported microfluidic coflow step-emulsification method can be used to generate highly monodispersed droplets, the droplet diameter (d) is constrained by the microchannel height (b), d≳ 3 b , while the production rate is limited by the maximum capillary number of the step-emulsification regime, impeding emulsification of highly viscous liquids. In this paper, we report a novel, gas-assisted coflow step-emulsification method, where air serves as the innermost phase of a precursor hollow-core air/oil/water emulsion. Air gradually diffuses out, producing oil droplets. The size of the hollow-core droplets and the ultrathin oil layer thickness both follow the scaling laws of triphasic step-emulsification. The minimal droplet size attains d≈ 1.7 b , inaccessible in standard all-liquid biphasic step-emulsification. The production rate per single channel is an order-of-magnitude higher than that in the standard all-liquid biphasic step-emulsification and is also superior to alternative emulsification methods. Due to low gas viscosity, the method can also be used to generate micron- and submicron-sized droplets of high-viscosity fluids, while the inert nature of the auxiliary gas offers high versatility. [Figure not available: see fulltext.]

Original languageEnglish
Article number86
JournalMicrosystems and Nanoengineering
Volume9
Issue number1
DOIs
Publication statusPublished - Dec 2023

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Huang, B., Ge, X., Rubinstein, B. Y., Chen, X., Wang, L., Xie, H., Leshansky, A. M., & Li, Z. (2023). Gas-assisted microfluidic step-emulsification for generating micron- and submicron-sized droplets. Microsystems and Nanoengineering, 9(1), Article 86. https://doi.org/10.1038/s41378-023-00558-4