High efficiency micromixing technique using periodic induced charge electroosmotic flow: A numerical study

Micromixers due to their prominence in Lab-On-a-Chip (LOC), biomanufacturing and chemical engineering applications are of great significances and emphases. In this paper, a 3D transient single phase solver has been developed in the open source code package, OpenFOAM, to investigate mixing efficiency and mixing length of a T-junction micromixer based on AC electroosmotic flow for both Newtonian and non-Newtonian fluids. The mathematical model and the developed solver are validated with existing data in the literature and the effects of substantial parameters such as AC amplitude, period of oscillation and conducting edges are investigated and the optimum range of each parameter are proposed to obtain simultaneously a high mixing efficiency and a relatively short mixing length. Present study shows that by using conducting edges, due to their capability of creating strong vortices, a high mixing efficiency and a short mixing length is achievable. Results show that via implementation of AC electric field as well as conducting edges, the mixing efficiency of 99% in a considerably short mixing length i.e. 20 mu m even in relatively high flow rates is obtainable. Since the mixing length is depended on the height of microchannel, in order to attain the capability of comparing achieved mixing length with findings of previous studies, a dimensionless parameter, Lm*, is proposed. Comparing of the value of this parameter for the present work and previous studies revealed that the presented micromixer can reduce the dimensionless mixing length up to 60%.