Simplified dynamical model for optical response of electrofluidic displays

In this work we analyze the switching behavior of an electro-fluidic pixel in separate stages. For 'on' switching we consider the motion leading to oil film rupture (initiation stage), fast oil-dewetting and a slower droplet rearrangement stage. For 'off' switching we consider fast oil wetting and surface reforming to the flat (dark) state. A dynamic model derived from an overall energy balance analysis has been employed to describe the optical response inside an electrofluidic display (EFD) pixel for the oil dewetting and wetting stages. By comparison with the experimental electro-optic response data, the accuracy and shortcomings of this model can be illuminated. The optical response asymmetry between on and off-switching and optical response delay during the on-switching process are well described and explained. In addition, the liquid film reforming dynamics and electrohydrodynamic instability analysis are used to estimate the oil film rupture and film reforming times very well. This study provides a straightforward approach to describe the complicated electrofluidic switching dynamics inside an EFD pixel, which may guide the further optimization of EFD device design and driving schemes.