Impedance detection integrated with dielectrophoresis enrichment platform for lung circulating tumor cells in a microfluidic channel.

Enrichment and detection of rare cells are essential in many biological and medical applications. In this study, circulating tumor cells were detected by combining dielectrophoretic (DEP) manipulation and impedance measurement using circular microelectrodes within a single microfluidic device. A prototype of the device was fabricated through standard soft-lithography. With the proposed microchip, target cells (lung cancer cells, A549) were guided toward the center of the working region due to the action of positive DEP and hydrodynamic drag forces and were then trapped onto the desired sensing electrodes. Impedance was measured to identify the presence of cells. Impedance spectroscopy was conducted at different numbers of cells. Linear characteristics were found using differential analysis technique. Experimental results showed that the impedance sensor can detect A549 cell line with low cell number at the appropriate frequencies. Limit of detection (LOD) of approximately 3 cells was achieved at frequencies near 50 kHz. This simple, rapid, label-free, and low-cost approach may open up new opportunities for developing cell diagnosis systems for future applications.