Circulating tumor cells are much lower in numbers compared to the other cells in body fluids. In one mL of blood, 1-3000 CTCs might exist in a sea of a billion red blood cells and a few million white blood cells. However, microfluidic cell sorting chips are well known for their capacity to handle a small amount of bodily fluids at low concentrations. Various microfluidic designs have been implemented to isolate CTCs from different bodily fluids and concentrations.