  A novel micro device with a mechanism of split and recombination (SNR) for
rapid fluidic mixing and reaction, named a SNR micro-reactor, was designed,
fabricated and systematically analyzed. This SNR micro-reactor possessing an
in-plane dividing structure requires only simple fabrication. We investigated
this reactor and compared it numerically and experimentally with a
slanted-groove micromixer (SGM). From the numerical results the mixing indices
and mixing patterns demonstrated that the mixing ability of the SNR
micro-reactor was much superior to that of the SGM. From a mixing test with
phenolphthalein and sodium hydroxide solutions, the mixing lengths of the SNR
micro-reactor were less than 4 mm for a Reynolds number over a wide range (Re =
0.1 - 10). From a comparison of mixing lengths, the results revealed also that
the SNR micro-reactor surpassed the SGM in mixing performance by more than 200
%. As a reaction length is a suitable test of the performance of a reactor, we
introduced a redox reaction between ascorbic acid and iodine solutions to
assess the reaction capability of these micro devices ; the reaction lengths of
the SNR micro-reactor were much shorter than those of a SGM. The SNR
micro-reactor has consequently a remarkable efficiency for fluid mixing and
reaction.
