the micromixer with overlapping - crisscross entrance incorporated with the grooved microchannel , is used effectively for mixing two or more fluid streams . the x - shape overlapping - crisscross inlet ports wherein two microfluidic channels contact over a small area , allow the fluid streams flow through and create the tumbling inside the micromixer . then merging with some patterned grooves on the walls also induces swirling motion . as a result , the folding and stretching effects of the flow are augmented to amplify the fluid mixing of two or more streams of the inlet fluids within a relative short distance in the micromixer . all of the flow streams are actuated with either pressure driven by a syringe pump or capillary electrophoresis . the present invention is applicable for micro total analysis systems and drug delivery systems .