Mixing of binary or multi-components fluid streams can be difficult in a microchannel, because it relies on diffusion. In the microscopic scale, it is not practical to use mechanical agitation. Therefore, a high performance passive mixing strategy needs to be introduced. In this paper, a study of the influence of a wider range of geometric parameters on passive mixing is reported. In respect to the nature of laminar flow in a microchannel, the geometric parameters were designed to favour lateral convection. Hence, the dispersion of the solutes was not only driven by diffusion, but also, and more importantly, by the convection in the lateral direction. Geometric parameters versus the mixing performance were simulated for T-type mixers using a computational fluid dynamic (CFD) solver for microfluidics. Preliminary experimental results are also presented. The shape of the obstacles used for passive mixing in the microchannels are compatible with current micromachining technology, and therefore, the optimised results can be applied to practical design of microfluidic devices.
The authors wish to express their gratitude to the Cooperative Research Centre (CRC) for Microtechnology for the support in this research project. Dr Rowan Deam also provided very helpful discussions with the authors.