A rapid three-dimensional vortex micromixer utilizing self-rotation effects under low Reynolds number conditions

This paper proposes a novel three-dimensional (3D) vortex micromixer for micro-total-analysis-systems (μTAS) applications which utilizes self-rotation effects to mix fluids in a circular chamber at low Reynolds numbers (Re). The microfluidic mixer is fabricated in a three-layer glass structure for delivering fluid samples in parallel. The fluids are driven into the circular mixing chamber by means of hydrodynamic pumps from two fluid inlet ports. The two inlet channels divide into eight individual channels tangent to a 3D circular chamber for the purpose of mixing. Numerical simulation of the microfluidic dynamics is employed to predict the self-rotation phenomenon and to estimate the mixing performance under various Reynolds number conditions. Experimental flow visualization by mixing dye samples is performed in order to verify the numerical simulation results. A good agreement is found to exist between the two sets of results. The numerical results indicate that the mixing performance can be as high as 90% within a mixing chamber of 1 mm diameter when the Reynolds number is Re = 4. Additionally, the results confirm that self-rotation in the circular mixer enhances the mixing performance significantly, even at low Reynolds numbers. The novel micromixing method presented in this study provides a simple solution to mixing problems in the lab-chip system.