Analytical Sciences

Shape of the Liquid–Liquid Interface in Micro Counter-Current Flows

Arata AOTA,* Akihide HIBARA,** Yasuhiko SUGII,*** and Takehiko KITAMORI***

*Institute of Microchemical Technology Co., Ltd., 3-2-1 Sakado, Takatsu, Kawasaki, Kanagawa 213–0012, Japan
**Institute of Industrial Science, The University of Tokyo, 4-6-1 Komaba, Meguro, Tokyo 153–8505, Japan
***Department of Applied Chemistry, School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo 113–8656, Japan

We investigated the shape of the liquid–liquid interface in micro counter-current flows formed within microchannels. The pressure balance at the interface was calculated based on the interface geometry. Although the shape should be an arc under laminar flow, a large deformation near the center of the microchannel was observed. In the center of the microchannel, Laplace pressure (171 – 450 Pa) was induced toward the aqueous phase. In contrast, near both sidewalls, Laplace pressure (81 – 166 Pa) was induced toward the organic phase. This result suggests that opposing flow occurs in the adjacent phases near the interface, with spiral-like flow generation.

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