Fundamental challenges in electrowetting: from equilibrium shapes to contact angle saturation and drop dynamics

Electrowetting is a versatile tool for manipulating typically submillimetre-sized drops in various microfluidic applications. In recent years the microscopic understanding of the electrowetting effect has substantially improved leading to a detailed description of the drop shape and the (singular) distribution of the electric field in the vicinity of the contact line. Based on these findings, novel quantitative models of contact angle saturation, the most important and longstanding fundamental problem in the field, have recently been developed. Future challenges arise in the context of dynamic electrowetting: neither the translational motion of drops nor the generation of internal flow patterns are currently well understood.