Dynamic behaviors of microdroplets in convergent microchannels under the effect of dielectrophoresis

The convergent microchannel is widely applied to connect microchannels with different sizes to avoid sharp changes of the flow field. It is important to investigate the dynamic properties in the convergent microchannel to promote the development of microdevices. Numerical simulation method is used to study the dynamic behaviors of microdroplets in a convergent microchannel. The microchannel is embedded with electrodes and alternating current (AC) is applied on the electrodes. Under the effect of nonuniform electric field, dielectrophoresis force is defined as the driving force to manipulate the microdroplets in the convergent microchannel. In this study, the surface tension is considered in the Navier-Stokes equations. The influence of dielectric constant and magnitude of voltage on the dynamic behaviors of microdroplets are analyzed in details. According to the results, the velocity of the microdroplet is proportional to the dielectric constant and voltage in the convergent microchannel. This can provide an efficient method to control the droplet merging process during the biological or chemical experiments.