Continuous particle focusing in a waved microchannel using negative dc dielectrophoresis

We present a waved microchannel for continuous focusing of microparticles and cells using

negative direct current (dc) dielectrophoresis. The waved channel is composed of consecutive

s-shaped curved channels in series to generate an electric field gradient required for

the dielectrophoretic effect. When particles move electrokinetically through the channel, the

experienced negative dielectrophoretic forces alternate directions within two adjacent

semicircular microchannels, leading to a focused continuous-flow stream along the channel

centerline. Both the experimentally observed and numerically simulated results of the focusing

performance are reported, which coincide acceptably in proportion to the specified dimensions

(i.e. inlet and outlet of the waved channel). How the applied electric field, particle size and

medium concentration affect the performance was studied by focusing polystyrene

microparticles of varying sizes. As an application in the field of biology, the focusing of yeast

cells in the waved mcirochannel was tested. This waved microchannel shows a great potential

for microflow cytometry applications and is expected to be widely used before different

processing steps in lab-on-a-chip devices with integrated functions.