Design and Simulation of an Open EWOD Based Digital Microfluidic Device for Droplet Actuation Using COMSOL

A novel open Electrowetting on Dielectric based device is designed and droplet actuation is investigated by simulations using COMSOL Multiphysics. Three different dielectric materials HfO2, Al2O3, and Si3N4 are used for simulations. The pressure difference in the droplet with time, the velocity of the droplet and the contact angle due to voltage (θv) are investigated and it is observed that the HfO2 dielectric layer provides better actuation of a droplet. Layer optimization is done by varying the thickness of the hydrophobic (Teflon) and dielectric layers. Investigation of the relevant parameters reveals that a combination of Teflon and HfO2 layer both of thickness of 20 nm provides superior droplet actuation on the device. Actuating voltage is varied from 0.5 to 5 V to study the velocity of the droplet and contact angle due to voltage (θv). Variation of the voltage drop at the leading side of the droplet and contact angle due to voltage (θv) are calculated for different permittivity of the droplet. The scheme can be potentially used as a digital microfluidic device for voltage-driven droplet actuation of a wide variety of biological fluids.