Realization of planar mixing by chaotic velocity in microfluidics

We present the design, fabrication and characterization of an effective planar passive micromixer with relatively simple construction for microfluidic applications. This micromixer consists of a zigzag microchannel in which realization of fluid mixing is expected because the variation of the flow velocity direction and magnitude in the channels may cause the laminar flow to become chaotic. Simulations were made to study the influence of geometry of the microchannel on the mixing effect and it has been found that the turning angle plays a very important role in the mixing process. Prototype devices were fabricated using polydimethylsioxane soft lithography technology. Mixing efficiency of the micromixer was examined by tracing the color uniformity of de-ionized water and red ink travelling through the microchannel. It was found that, for these two flows with a wide range of flow rates, the resulted fluid at the outlet of the micromixer would always show good color uniformity, indicating a high mixing efficiency. A prototype micromixer system for future fast chemical and biological analysis was proposed and fabricated based on this design. Easy to fabricate and use, we believe that our micromixer can be used as a general-purpose component for microfluidic systems.