Immunoaffinity-based separation is high specific and could segregate different sizedcirculating tumor cells (CTCs), particularly for small sized-cells. Due to the big gap spacing between microposts, purity is relatively high, CTCs captured through collision and normal blood constitutes passing through, mitigating clogging. However, the complex structure and long modification procedure with expensive antibodies limited application of this approach. Immunoaffinity-based capture has the dilemma of EpCAM expressions in distinct carcinomas as the usual surface biomarker. For instance, in the common cell line used, EpCAM is highly expressed in MCF-7 (7287 antigens), HCT116 (6000 antigens), COLO205 (18560 antigens) and HT29 (13853 antigens), however, low expressed in HepG2 (2727 antigens), A549 (33 antigens) and Hela (8 antigens).