Dielectrophoretic effect on droplet dynamic behaviors in microchannels

Dielectrophoresis is of particular interest in droplet manipulation because of its ability to manipulate droplets based on their unique dielectric properties. With the help of different kinds of electrodes, the droplet dynamic behaviors can be manipulated to complete various tasks. In this work, both the experimental and numerical simulation methods are applied to find out a way to slow down the velocity of the droplets which is very helpful for droplets detection. For the experimental part, the microchannels are embedded with various kinds of electrodes near their microchannel walls instead of being arranged in the microchannel, and the direct current voltages are applied to the electrodes to generate a prescribed electric field intensity gradient in the longitudinal direction. A more accurate simulation model is made to analyze the mechanisms of the dielectric effect on the droplet dynamic behaviors in detail. The dynamic behaviors and dielectric characteristics of the microdroplets are investigated by studying the moving velocity, the deformation, the dielectrophoretic force and distributions of the electric field intensity. According to the results presented herein, both the dielectrophoretic force and interfacial tension have significant effects on the droplet dynamic behaviors. The method proposed in this work can manipulate the droplet velocity efficiently, and the velocity of the droplets can be decreased to one-fifth of the initial velocity. Therefore, it is important to focus on this method to make a contribution to droplet non-damage detection in biological and chemical experiments.