Stable biphasic interfaces for open microfluidic platforms
We present an open microfluidic platform that enables stable flow of an organic solvent over an aqueous solution. The device features apertures connecting a lower aqueous channel to an upper solvent compartment that is open to air, enabling easy removal of the solvent for analysis. We have previously shown that related open biphasic systems enable steroid hormone extraction from human cells in microscale culture and secondary metabolite extraction from microbial culture; here we build on our prior work by determining conditions under which the system can be used with extraction solvents of ranging polarities, a critical feature for applying this extraction platform to diverse classes of metabolites. We developed an analytical model that predicts the limits of stable aqueous-organic interfaces based on analysis of Laplace pressure. With this analytical model and experimental testing, we developed generalized design rules for creating stable open microfluidic biphasic systems with solvents of varying densities, aqueous-organic interfacial tensions, and polarities. The stable biphasic interfaces afforded by this device will enable on-chip extraction of diverse metabolite structures and novel applications in microscale biphasic chemical reactions.
KeywordsMicrofluidics Liquid-liquid extraction Biphasic interfaces Metabolomics
This work was funded by the University of Washington, NIH K12DK100022, and NIH R01CA185251 (JY). We gratefully acknowledge Dr. David Beebe for helpful discussions and the Microtechnology Medicine and Biology (MMB) laboratory for supporting preliminary experiments that laid the foundation for this work. We thank Alexander Howard and Drs. Mark Scalf and Lloyd Smith for their contributions to preliminary experiments.
Compliance with ethical standards
Conflicts of interest
The authors acknowledge the following potential conflicts of interest in companies pursuing open microfluidic technologies: JY: Stacks to the Future, LLC, EB: Tasso, Inc., Salus Discovery, LLC, and Stacks to the Future, LLC, ABT: Stacks to the Future, LLC.
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