Mixing of magnetic and nonmagnetic fluids in a microchannel under homogeneous magnetic fields

M. Watanabe - H. Ibe - A. Aki - Y. Nagaoka - H. Morimoto - T. Maekawa

Bio-Nano Electronics Research Centre, Toyo University, 2100, Kujirai, Kawagoe, Saitama 350-8585, Japan

Abstract
We investigate the mixing of magnetic and nonmagnetic fluids in a microchannel under external magnetic fields experimentally. Microchannels are fabricated by the soft lithography method. Two channels meet at a Y-junction. The width and the depth of the inlet channels are 100 μm. The channel after the Y-junction, which we call an outlet channel, has the same depth as the inlet channel and its width is 200 μm. A water-based magnetic fluid (W-40, Taiho Industry, Co. Ltd.) is injected into one inlet and water is injected into the other. The flow rate in each inlet is changed from 5 to 45 μl/min. We apply a homogeneous DC magnetic field and observe flow patterns in the outlet channel after the Y-junction. We find that the DC magnetic field enhances the mixing of the fluids. We also apply AC and rotational magnetic fields and analyze the effect of the intensity and frequency of the magnetic fields on the mixing of the fluids in detail. Figs 7, Refs 18.