Static micromixers using alternating whirls and lamination

We have designed, fabricated and compared four different types of static micromixers, including the mixers using straight channel flow, microblock-induced alternating whirl flow, microchannel-induced lamination flow and combined alternating whirl-lamination flow. Among them, the alternating whirl-lamination (AWL-type) mixer, composed of rotationally arranged microblocks and dividing microchannels, is effective to reduce the mixing length over wide flow rate ranges. We characterize the performance of the fabricated mixers through the flow visualization technique using phenolphthalein solution. We verify that the AWL-type micromixer shows mixing lengths of 2.8-5.8 mm for Re = 0.26-26 with a pressure drop under 5 kPa. Compared to previous mixers, requiring mixing lengths of 7-17 mm, the AWL-type micromixer results in 60% reduction of the mixing lengths. Due to the reduced mixing lengths within reasonable pressure drop ranges, the present micromixers have potential for uses in miniaturized micro-total-analysis-systems (mu TAS).