Theoretical and Experimental Studies on Filtering Tumor Cells from Blood Cell Mixtures with Dam Structure in Microfluidic Devices

Here, a filter with series of pools and dams structures was designed and fabricated, utilizing size difference between tumor and blood cells. The cell mixtures were successfully filtrated out by the filter, and separation efficiency was up to 99.9%. To evaluate the filter, physical models were made to describe the behaviors of different cells in microfluidic systems. As the ability of cell deformation depends on both cells´ size and excess surface index (ESI), we measured the excess membrane area of different cells, and got tumor cell´s ESI is 61.7% ~ 81% comparing with red blood cell (RBC) (44%) and white blood cell (WBC) (84%~137%). Then from the formulas we deduced, we get the filtering limitations of RBC, WBC, and tumor cell are respectively, around 1.8 mum, 1.0-1.6 mum and 3.7-4.4 mum for dam structure; and 1.3 mum, 0.9-1.3 mum and 3-3.4 mum radius for pipes, which actually show conditions for separation. The accuracy and high flux of the filter provide possibilities to isolate cancer cells directly from the blood in real-time, which could become a potential therapy to cancers