MODELING AND SIMULATION OF UNEQUAL DROPLET SPLITTING IN ELECTROWETTING BASED DIGITAL MICROFLUIDICS

Electrowetting-on-dielectric (EWOD) is a highly efficient technology to perform biological and medical analyses through the manipulation of pico- to nano-liter droplets on digital microfluidic systems (DMS). Droplet splitting is one of the basic fluidic operations that play a vital role in microscale mixing and concentration control. This paper presents the results of numerical investigation of unequal droplet splitting. In order to gain insight into the mechanism of droplet splitting, a three-electrode splitting system is simulated in FLOW-3D (R) for given geometry and material properties. When unequal voltages are applied to the adjacent electrodes on both sides of a droplet the distribution of electric field exerts spatially varying stress causing the deformation of the interface. The resulting unequal fluid flow rates towards the activated electrodes are determined by the coupled electro-hydrodynamics. The results of multiple simulation runs in terms of liquid flow rates with different ratios of the applied voltage will be very useful in developing the open-loop model of droplet splitting that can be later adopted to design a controller for unequal splitting in DMS.