We describe a novel method for droplet transport combining electrowetting on dielectric (EWOD) and the diode-like behavior of valve metals to achieve unique actuation performance. While traditional EWOD droplet transport requires switching of voltage between multiple electrodes, our method, which we term continuous rectified electrowetting, utilizes a simple single electrode and a DC voltage to move a 50 μl droplet 28 mm with velocities up to 32 mm s(-1).

Electrowetting is the change in apparent surface energy of a liquid in an applied electric field. It has shown great promise in diverse applications including lab-on-a-chip and electronic displays. The electrowetting response is typically considered independent of the actuation voltage polarity. This paper describes a new approach that achiees actuation in different directions for positive and negative voltage polarities using the electrochemical characteristics of aluminum electrodes. This paper presents a concept for continuous actuation of a droplet using a single electrode and DC voltage based on this effect. Initial experiments demonstrate that droplet motion is possible. Measurements of voltage drop across aluminum electrodes confirms the polarity-dependent response of the electrodes.