A microfabricated module for isolating cervical carcinoma cells from peripheral blood utilizing dielectrophoresis in stepping electric fields

The ability to isolate rare cells, such as circulating tumor cells (CTC), circulating fetal cells, and stem cells, is important for medical diagnostics and characterization. The present study develops a microfabricated module that can effectively isolate cervical carcinoma cells (HeLa) from a peripheral blood sample. Circular microelectrodes that generate a stepping electric field by switching the electric field between adjacent electrode pairs by relays are designed herein. Positive dielectrophoretic cells are guided by the movement of the high-electric-field region. The magnitude of the dielectrophoresis (DEP) force acting on HeLa cells is about sevenfold that on red blood cells (RBCs) under a given electric field distribution in a sucrose medium, making it possible to separate HeLa cells from normal blood cells. Both HeLa cells and RBCs are pushed to the outermost electrodes when an outward stepping electric field (16 V peak-to-peak; 1 MHz) is applied. When an inward stepping electric field (10 V peak-to-peak; 1 MHz) is applied, the movement of HeLa cells toward the center electrodes is faster than that of RBCs. As a result, HeLa cells are concentrated onto the central microelectrode and isolated from the blood sample. Experimental results demonstrate the feasibility of isolating HeLa cells from blood samples.