Characterization of electrowetting actuation on addressable single-side coplanar electrodes

This paper studies and characterizes electrowetting-on-dielectric (EWOD) actuations on coplanar electrodes with an electrode-free cover plate or no cover plate. By arranging driving and reference electrodes on one plate, such an EWOD configuration can accommodate more sensing mechanisms from above and thus allows increased flexibility for system development. Various coplanar electrodes are tested for contact angle changes by EWOD with a focus on the effect of the percentage gap between electrodes and are found to be in good agreement with a simple analytical model. The droplet-moving devices demonstrate the successful moving, cutting and merging of droplets (~0.1 mul) in a parallel-plate configuration, i.e., between the driving plate with coplanar electrodes and the passive plate with no electrode. EWOD actuation in single plate configuration, i.e. no cover plate, is also demonstrated, adding additional flexibility for the system design.