Sessile drop response to a single wave electrokinetic excitation

Abstract

The response time for maximum drop deformation and its comparison with different time scales is established and verified with experiments. The applied fluctuation is achieved by applying a single wave perturbation of electrowetting with desired amplitude and frequency. To pinpoint the importance of the initial actuation conditions, the variance in the maximum drop deformation for a single wave perturbation is studied. The focus of this study was to analyze the maximum deformation of a drop for a wide range of actuation mechanism with a varied drop or surrounding medium viscosities. The drop response to this cyclic actuation is compared with the equivalent mass–spring–dampener system, and limitations of this approach are identified. Interestingly, the qualitative results were similar between the air and liquid medium cases, but the attainment of equilibrium configuration was dissimilar. As anticipated, the higher actuation magnitude and frequency deformed the drop significantly and thus altered the drop configuration. Higher viscosity of drops and the surrounding medium delayed the time to achieve the maximum deformation. Accurately predicting the time required for a drop to attain the maximum deformation is paramount for optimizing processes and based on microfluidics technology.