Effects of dc-dielectrophoretic force on particle trajectories in microchannels

A method of controlling the particle trajectory in a microchannel is demonstrated. The method utilizes the dc-dielectrophoretic (dc-DEP) force created around an insulating hurdle in a microchannel under an applied dc electric field. This method does not require a complicated electrode array which is commonly used in the conventional ac-DEP system. The “proof-of-principle” experiments were carried out using a straight microchannel with a rectangle-shaped hurdle in the middle. The experiments showed that the trajectories of the micron-sized particles can be controlled by the DEP force under electric-field strengths of 5–20kV∕m. To compare with the experimental results, the particle motion was simulated using the Lagrangian tracking method, taking into consideration of the electrophoretic force, the dielectrophoretic force, and the dielectric interaction between the particle and the channel wall. The numerical simulation based on the finite-element method showed a reasonable agreement with the experimental data.