Electrophoretic Behavior of Droplets Manipulated by Charging and Electrode Modification

level and strengthening the electrophoretic driving force. However, direct contact between charged droplets and bare electrodes caused charge exchange, polarity reversal, and rebound, leading to repeated back-and-forth migration. To convert the enhanced electrophoretic migration into effective coalescence, electrode surface insulation was introduced. By suppressing rapid charge exchange between droplets and the metal electrode, the insulated electrode enabled charged droplets to be directionally captured, slide along the electrode surface, and coalesce with neighboring droplets. These results indicate that droplet charge enhancement and electrode-interface regulation can effectively promote electrophoretic migration and directional coalescence under a DC electric field, providing guidance for the design of efficient DC electrostatic coalescers.