Pool-dam structure based microfluidic devices for filtering tumor cells from blood mixtures

In this paper, a microfilter device with a series of pool and dam structures was designed and fabricated. To evaluate the efficiency of the filter, physical models were established to describe the behaviors of different kind of cells in the microfilter device. In our physical model, both the physical size effect and the deformability of cells are considered. As the deformability of a cell depends largely on its excess surface area index (ESI), the ESI of the tumor SPC-A-1 cells was measured and found to be as 61.7-81%. From our measurements on red blood cells (RBCs) (44%) and white blood cells (WBCs) (84-137%), we have calculated the ultimate width of the dam gap structure to prohibit RBCs, WBCs, and tumor cells to be around 1.8 mu m, 1.0-1.6 mu m, and 3.7-4.4 mu m, respectively. The experimental results showed that tumor cells (SPC-A-1) were successfully sorted from cell mixtures by the pool-dam structure filter under a pressure of 200 MM H2O, and that the separation efficiency reached 99.9%. Both theoretical and experimental analyses provided positive evidence for the physical isolation of cancer cells directly from the blood in real-time through microfluidic structures. Copyright (C) 2006 John Wiley & Sons, Ltd.