Analytical Sciences

Integrated Multilayer Flow System on a Microchip

Akihide HIBARA,*  Manabu TOKESHI,** Kenji UCHIYAMA,** Hideaki HISAMOTO,* and Takehiko KITAMORI*^,**^,***

*Department of Applied Chemistry, School of Engineering, The University of Tokyo, Hongo, Bunkyo, Tokyo 113-8656, Japan
**Integrated Chemistry Project, Kanagawa Academy of Science and Technology, Sakado, Takatsu, Kawasaki 213-0012, Japan
***Precursory Research for Embryonic Science and Technology 21, Japan Science and Technology Corporation

We utilized microchip technology and found that the multilayer flow of liquids can be formed in microchannels. Liquid/liquid interfaces were formed parallel to the side wall of the microchannels, because the surface tension and friction force are stronger than the force of gravity. A water/ethylacetate/water interface was formed in a 70-um-wide and 30-um-deep channel. The interface was observed to be quite stable and to be maintained for a distance of more than 18 cm. As an example of a multilayer flow application, we demonstrated the liquid/liquid extraction of Co-dimethylaminophenol complex in a microchannel. The solvent-extraction process of the complex into m-xylene in the multilayer flow was found to reach equilibrium in 4 s, while it took 60 s in a simple two-phase extraction.

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