Influence of polarization on contact angle saturation during electrowetting

Electrowetting is widely used to manipulateliquids on adielectricsurface by changing the wettability of the solid-liquid interface using an externally appliedelectric field. While the contact angle can be adequately predicted at low fields using Lippmann's model, there is a large disagreement with experimental behavior at high fields, where the contact angle saturates. Previous attempts to explain this saturationeffect (by considering a range of different mechanisms) have led to models that are applicable only to limited field ranges. Here, we use a model for the solid-liquid interfacialsurface energy (based on a dipole-dipole interaction) to describeelectrowetting and find that this explains the contact angle change at both low (continuous change) and high (saturation) fields. The model is compared with measured contact angle changes for both water and ethylene glycolliquids, with good agreement over the whole field range.

Source: Applied Physics Letters - November 21, 2016 Category: Physics Authors: Chen Jiang, Hanbin Ma, David G. Hasko and Arokia Nathan Source Type: research