Sputtered–Anodized $\hbox{Ta}_{2}\hbox{O}_{5}$ as the Dielectric Layer for Electrowetting-on-Dielectric

Abstract

Evaluating the anodized tantalum pentoxide (Ta2O5) that has been recently reported as a dielectric for low-voltage electrowetting-on-dielectric (EWOD) devices, we find a severe deterioration in performance if the working liquid is actuated with positive dc voltage. In an effort to reduce the limitation of this otherwise attractive dielectric material for EWOD, proposed herein is a Ta2O5 layer prepared by anodizing a sputtered Ta2O5 film. This sputtered-anodized Ta2O5 allows the use of positive dc signals, while maintaining the low-voltage actuation for which the anodized Ta2O5 was originally introduced. All the EWOD tests were performed with a conductive liquid droplet in an air environment.