3D focusing of micro-scale entities in dielectrophoretic microdevice

Herein, we report a dielectrophoretic microdevice mathematical model to achieve 3D focusing for micro-scale entities. The device has two pairs of independently controllable electrodes with each pair positioned on the microchannel's sides; every electrode of each pair protrudes slightly into the microchannel. The model is composed of equations describing voltage, electric field, fluid flow and equations of motion. The model took consideration of different forces including dielectrophoresis, drag, gravity, buoyancy, virtual mass and inertia to the motion of the micro-scale entity. The model is solved specifically by finite difference methods. The micro-scale entity is 3D focused at microchannel centre for equal applied voltage and focused away from the channel for unequal applied voltage. Steady-state vertical position is dependent on applied voltages, electrode protrusion width and microchannel height while being independent of volumetric flow rate, initial positions and radius of micro-scale entity. No increase in vertical position occurs beyond the threshold values of microchannel height and applied voltage. The model is validated with experimental results from literature. © 2019 Wiley Periodicals, Inc.