Reversible ultralow-voltage liquid-liquid electrowetting without a dielectric layer
Electrowetting-on-dielectric devices typically have operating voltages of 10-20 V. A reduction in the operating voltage could greatly reduce the energy consumption of these devices. Here, the fully reversible one electrolyte electrowetting of a droplet on a solid metal surface is reported for the first time. A reversible change of 29o for an 800 mV step is achieved. The effect of surface roughness, electrolyte composition, electrolyte concentration and droplet composition is investigated. It is found that there is a dramatic dependence of the reversibility and hysteresis of the system on these parameters, contrary to theoretical predictions. When a 3-chloro-1-propanol droplet is used, a system with no hysteresis and a 40o change in angle is achieved.