Microfluidic droplet-based liquid-liquid extraction

Pascaline Mary, Vincent Studer, Patrick Tabeling
Anal. Chem.. 2008-04-01; 80(8): 2680-2687
DOI: 10.1021/ac800088s

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1. Anal Chem. 2008 Apr 15;80(8):2680-7. doi: 10.1021/ac800088s. Epub 2008 Mar 20.

Microfluidic droplet-based liquid-liquid extraction.

Mary P(1), Studer V, Tabeling P.

Author information:
(1)Laboratory of Microfluidics, UMR Gulliver, 75005 Paris, France.

We study microfluidic systems in which mass exchanges take place between moving
water droplets, formed on-chip, and an external phase (octanol). Here, no
chemical reaction takes place, and the mass exchanges are driven by a contrast in
chemical potential between the dispersed and continuous phases. We analyze the
case where the microfluidic droplets, occupying the entire width of the channel,
extract a solute-fluorescein-from the external phase (extraction) and the
opposite case, where droplets reject a solute-rhodamine-into the external phase
(purification). Four flow configurations are investigated, based on straight or
zigzag microchannels. Additionally to the experimental work, we performed
two-dimensional numerical simulations. In the experiments, we analyze the
influence of different parameters on the process (channel dimensions, fluid
viscosities, flow rates, drop size, droplet spacing, …). Several regimes are
singled out. In agreement with the mass transfer theory of Young et al. (Young,
W.; Pumir, A.; Pomeau, Y. Phys. Fluids A 1989, 1, 462), we find that, after a
short transient, the amount of matter transferred across the droplet interface
grows as the square root of time and the time it takes for the transfer process
to be completed decreases as Pe-2/3, where Pe is the Peclet number based on
droplet velocity and radius. The numerical simulation is found in excellent
consistency with the experiment. In practice, the transfer time ranges between a
fraction and a few seconds, which is much faster than conventional systems.

DOI: 10.1021/ac800088s
PMID: 18351786 [Indexed for MEDLINE]

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