Model-Based Performance Study of Dielectrophoretic Flow Separator

This article presents model-based analysis of a dielectrophoretic microfluidic flow separator in terms of separation efficiency and purity. The device employs interdigitated transducer electrodes on the bottom surface, and they run over the entire width of the microchannel. The device realizes type-based separation, specifically electrical properties, by capturing one type of microscale entity on the electrode surface due to positive dielectrophoresis (DEP) while keeping the other type suspended in the medium due to negative DEP. The model describes the trajectory of microscale entities, electric field potential, and fluid velocity in the microchannel and accounts for forces related to DEP, sedimentation, drag, virtual mass, and inertia. The model is used for parametric study using polystyrene and silica microparticles with radius of 3 μm; parameters analyzed are flowrate, applied electric potential, number of electrode pairs, and electrode/gap length. Separation efficiency of the levitated microscale entity is 100% for all input parameters, while that of the captured microscale entity varies. Separation purity of the captured microscale entity is 100% for all input parameters, as long as the other type remains levitated, while that of the levitated microscale entity varies. The model developed in this article can help select parameters for achieving the desired level of performance metrics. The model is validated using experimental data on levitation of latex microparticles for voltages of 1-8 V_pp in a microfluidic device with electrode/gap length of 20 μm and height of 120 μm. The novelty of the model is that it is dynamic and can model the simultaneous capture and levitation of microscale entities in the microfluidic device.