Actuating a Selectively Metallized Plate with Electrowetting Force*

Electrowetting on dielectric (EWOD) driven micropump actuators can be integrated into microfluidic reconfigurable radio frequency (RF) devices. In this research, a technique will be introduced to actuate an RF metallized plate using EWOD forces. In the proposed configuration, the plate is supported by four droplets. The top plate is coated with a hydrophilic material and the bottom plate is coated with a hydrophobic material. The actuation velocity determines the tuning speed of the device the velocity increases by maximizing the actuation force, minimizing the moving mass (droplets and metallized plate), and reducing all resistances (contact line drag, fluid drag). To achieve this goal, first, we build an analytical model of EWOD actuation that can calculate the relation between the physical dimensions and velocity of the EWOD-actuated system as a function of input voltage so we can evaluate whether EWOD can overcome the drawbacks that are expected with piezoelectric actuation, such as low accuracy, large size, and difficulty in reliable actuation to multiple positions. In addition, the experiments are employed to verify the proposed model. The model is validated with an EWOD experiment, and the data demonstrates less than a 5.6% error between the measured and predicted maximum plate velocity for different voltage inputs.