In medical science, preparing a high purity sample of certain kinds of cells plays an important role in studying the characteristics and functionality of cells, detecting in vitro harmful pathogens and helping to find ways of preventing and treating diseases that cause cellular disorders in the human body. The goal of this research is to improve the spiral microchannel with stair-like cross section in order to separate white blood cells from whole blood. First, the efficiency of this method was evaluated numerically, using a developed finite element model. Then, the desired microchannel mold was made using the micromiling method, and we fabricated the chip using soft lithography and pasting...