Mixing enhancement of novel passive microfluidic mixers with cylindrical grooves

The mixing is difficult but fundamentally important in microfluidic systems. Three simple yet novel passive mixers were designed and fabricated with cylindrical grooves adjoining to the main straight channel. A serial of systematic simulations and experiments have been done with the increase of the groove-depth, ranging from 0 to 3/4-cylindrical groove. All results confirmed the improvement of mixing in these mixers in a short distance (<20 mm). Over a wide range of Reynolds number (from 0.1 to 100), the ratios of ‘the percentage of mixing (φ)’ of the mixer with 1/4-cylindrical grooves to that with no grooves increase from 1.23 to 5.11. All designs are very easy to fabricate and have great potential to be integrated into a total microfluidic system.

► Three mixers were fabricated by embedding cylindrical grooves into the main channel.
► Simulated and experimental results confirmed the mixing enhancement of the mixers.
► The effect of cylindrical grooves is more pronounced at greater flow rates.
► Our designs can be easily incorporated into a total microfluidic system.