Fetal nucleated red blood cells are special cells only existed in the peripheral blood of pregnat woman and fetus. This talk start from brief introduction of microfluidics development, then summarizing the basic principle and procedure used in the FDA approved porduct CellSearchTM and its subsequent developments in circulating tumor cells isolation, and followed by the research in our group on the capturing, analyzing of the circulating tumor cells from cancer patients and fetal nucleated red blood cells from the peripheral blood of pregnant women and their immunofluorescent assay.