| dc.description.abstract | The various parameters affect the dynamic behavior of electrowetting discussed in the study. From Lippman-Young′s equation, the applied voltage is an important parameter affecting electrowetting. It affects the changes of contact angle. However, the applied voltage affects not only the changes of contact angle, but also the reaction time of electrowetting and the changes of drop shape. Besides the applied voltage, there are other parameters affecting electrowetting such as the concentration of working fluid、the roughness of substrate surface、the thickness of dielectric layer. These parameters were discussed less in previous studies.
When the concentration of working fluid is increased, the changes of contact angle are larger under the same applied voltage, and the reaction time of elctrowetting is shorter. However, as the concentration is above the specific concentration, the changes of contact angle no longer change. The situation is similar to contact angle saturation induced by voltage. As the voltage is above the specific voltage, the changes of contact angle are the same. We call it saturation concentration (about 10 mM). The surface roughness also affects the electrowetting effect. With the increase of roughness, the electrowetting effect is insignificant, so the change of contact angle are smaller. At last, the thickness of dielectric layer strongly affects the electrowetting effects. Two dielectric materials are employed in this study. They are oxidation graphite films and oxidation steel films. The thicker the dielectric layer is, the more insignificant the electrowetting effect is. The changes of contact angle is smaller. Through the control of these parameters, the more effective manipulation is expected.
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