A barrier embedded Kenics micromixer

Abstract

It is of great interest to enhance the mixing performance in a microchannel in which the flow is usually characterized by a low Reynolds number (Re) so that good mixing is quite difficult to achieve. In this regard, we present a new chaotic passive micromixer, named the barrier embedded Kenics micromixer (BEKM). In the BEKM, a higher level of chaotic mixing can be achieved by combining two general chaotic mixing mechanisms: splitting/reorientation and stretching/folding. The splitting/reorientation mechanism is obtained by the alternating arrangement of helical elements in the original Kenics mixer design. The stretching/folding mechanism is induced by periodic perturbation of the velocity field due to periodically inserted barriers along the cylinder wall while a relative helical flow is maintained by a helical element inside the pipe. In this study, the fully three-dimensional geometry of the BEKM was realized by micro-stereolithography, along with the Kenics micromixer and a circular T-pipe. Mixing performance was experimentally characterized in terms of an average mixing intensity via colour change of phenolphthalein. Experimental results show that the BEKM has better mixing performance than two other micromixers. The chaotic mixing mechanism proposed in this study could be applied to integrated microfluidic systems, such as the micro-total-analysis system, lab-on-a-chip and so on, as a mixing component.