Computational modeling and comparison of three co-laminar microfluidic mixing techniques

This study compares three common microfluidic mixing techniques: electroosmosis with patterned zeta potential, hydrodynamic focusing and physical constrictions. All three techniques provide a higher degree of mixing than a comparable channel without a mixer, but at the cost of higher power requirements. Of the three techniques, the electroosmotic mixer requires the greatest amount of power to produce a high degree of mixing, unless the channels are much smaller than those typical for microfluidic devices. The power requirement of the physical constriction mixer may be lowered by using multiple constrictions, with only a small loss in mixing effectiveness. The physical constriction mixer is recommended, since it has power requirements similar to the hydrodynamic focusing mixer but only requires the use of a single pump. However, if the mixing liquids contain particulates, a hydrodynamic focusing mixer may be preferred, because the physical constriction mixer may clog, depending on the particulate size.