Micro T-mixer as a rapid mixing micromixer

In this paper, micro T-mixers are fabricated and tested to investigate their feasibility as a rapid mixing micromixer. The micro T-mixers are fabricated out of a silicon substrate and bonded to a Pyrex glass plate to enable their mixing performances be observed and characterized. The mixing is characterized using a blue dye and a colourless liquid, the results are further verified by the hydrolysis reaction of dichloroacetyl phenol red. Different pressures are applied onto the inlets of the micro T-mixers and their corresponding mixing performances are observed with an optical microscope. Liquid streams break up into striations at progressively higher Reynolds number of flow and there exists a Reynolds number, between 400 and 500, when these striations disappear into uniform concentration across the mixing channel. The observations are further supported by computer simulations, which enable the fast mixing to be explained by the asymmetrical flow conditions at the inlets, in addition to the generation of vortices and secondary flow at the junction. It is shown that for a micro T-mixer with a mixing channel having a hydraulic diameter of 67 mum, an applied pressure of 5.5 bar is sufficient to cause complete mixing within less than a millisecond after the two liquids make contact. (C) 2004 Elsevier B.V. All rights reserved