Enhancement of response speed of viscous fluids using overdrive voltage

Fast, identical response speeds over a full operating range are critical for electrowetting-driven devices such as liquid lenses, microswitches, and reflective displays. In this study, electrowetting actuation with overdrive signals is employed to reduce response time. We explore spreading behaviors and response time (i.e., the time required to reach equilibrium radius) of electrowetted droplets under various DC and overdrive electrowetting actuation conditions. When the droplet is actuated by an overdrive electrical signal, response time is reduced to as low as 1/25 of the response time using a DC signal. We present a theoretical model that considers contact angle saturation and predicts spreading dynamics of droplets under DC and overdrive electrowetting actuation to within 5% error. Using only signal control, our proposed method can be used for multiple practical electrowetting-based applications without any modification of the current platform of electrowetting systems.