Dielectrophoresis (
DEP), a technique used to separate particles based on different sizes and/or dielectric properties under nonuniform electric field, is a promising method to be applied in label-free, rapid, and effective cell manipulation and separation. In this study, a microelectromechanical systems-based, isolated 3D-electrode
DEP device has been designed and implemented for the label-free detection of multidrug resistance in K562
leukemia cells, based on the differences in their cytoplasmic conductivities. Cells were hydrodynamically focused to the 3D-electrode arrays, placed on the side walls of the microchannel, through V-shaped
parylene-C obstacles. 3D-electrodes extruded along the z-direction provide uniformly distributed
DEP force through channel depth. Cell
suspension containing resistant and sensitive
cancer cells with 1:100 ratio was continuously flown through the channel at a rate of 10 μL/min. Detection was realized at 48.64 MHz, the cross-over frequency of sensitive K562 cells, at which sensitive cells flow with the fluid, while the resistant ones are trapped by positive
DEP force. Device can be operated at considerably low voltages (<9 Vpp ). This is achieved by means of a very thin (0.5 μm)
parylene coating on
electrodes, providing the advantages offered by the isolation of
electrodes from the sample, while the working voltage can still be kept low. Results prove that the presented
DEP device can provide an efficient platform for the detection of multidrug resistance in
leukemia, in a label-free manner.