An effective passive microfluidic mixer utilizing chaotic advection

A Y-junction type micromixer with a square obstacle on the square-wave flow channel for enhancing the mixing ability by using the chaotic advection principle was designed and the mixing efficiency was measured. The micromixer was fabricated on quartz material by SF6/Ar inductively coupled plasma (ICP) etching. The mixing capability of the mixer was tested by mixing NaOH and phenolphthalein solutions and analyzing the color density from the image taken by a charge-coupled device (CCD) camera at a given position. The mixing characteristics were measured by varying the flow rate from the micropumps and the channel width of the mixer. The mixing percentage increased slowly with increasing flow rate, but rapidly with decreasing microchannel width.