EWOD actuation with electrode-free cover plate

A new configuration of electrowetting-on-dielectric (EWOD) actuations with electrode-free cover plates is presented. By removing electrodes from one plate, the device becomes more flexible for system development, broadening the choice of sensing mechanisms. Simple devices with various coplanar electrodes on a single side are used to measure contact angles and assess droplet movements. Contact angle changes with respect to applied voltages are in good agreement with our simple analytical model. Droplet moving devices demonstrate successful actuation of droplets (∼0.1 μl) in the gap between the plates with coplanar electrodes and the other with no electrode. Droplet cutting and merging are demonstrated to establish the fundamental fluidic operations with this new configuration. EWOD actuation on an open surface with removed top plate is also demonstrated.