Theoretical investigation of droplet splitting due to electrowetting on dielectric in a Hele–Shaw cell

Abstract

In this study, we investigated the electrowetting on dielectric (EWOD)-induced splitting behavior of droplets placed in a Hele-Shaw cell. The deformation behavior of the droplet was experimentally observed under various applied voltages. A theoretical model was proposed to express droplet behavior by balancing the surface tension, viscous force, and pressure acting the droplet. The effect of the dynamic contact angle was considered and used to estimate the capillary force along on the moving contact line. The results obtained from the theoretical model showed a qualitative agreement with the deformation behavior of the observed droplets. An approximate model was proposed to verify the observations that demonstrated that the contact line widths at the boundary between the positive and negative electrodes remain almost constant during the splitting process. The behavior of the contact line width was explained using the model, based on the minimum work required for droplet deformation during the splitting process.