Design and Evaluation of a Millifluidic Insulator-Based Dielectrophoresis (DEP) Retention Device to Separate Bacteria from Tap Water

Abstract

Water is a basic necessity critical to the survival of all living beings. However, many people around the world do not have consistent access to uncontaminated drinking water. Traditional water treatment methods, such as filtration and disinfection, require physical or chemical disinfectants and are prone to fouling. Dielectrophoresis (DEP) enables a system whereby polarized bioparticles exhibit lateral movement under the influence of applied, non-uniform electric fields. A single-stage, continuous flow, millimeter-sized DEP device was designed and fabricated to remove Escherichia coli K12 from contaminated tap water. Glass beads were used to alter the electric field distribution and create zones of high electric field to trap bacterial cells. The effect of varied voltages, flow rates and bead sizes on the removal efficiency was studied. The highest removal efficiency of E. coli K12 was 99.9%, with the device set at 60 V, a flow rate of 1.0 mL/min and a 200 µm bead size. Higher applied voltages, slower flow rates, and smaller bead sizes led to an increased reduction in bacteria. An optimized macro-scale system—with multiple stages of DEP—could be suitable for commercial use and would be an effective method of removing pathogens from polluted tap water.