Design, fabrication and characterization of low cost printed circuit board based EWOD device for digital microfluidics applications

Digital microfluidics (DMF) is an emerging liquid-handling technology that enables individual control over droplets on array of electrodes. In this paper a low cost approach for development and characterization of open configured electro wetting on dielectric (EWOD) based digital microfluidic device is presented. The array of electrodes pattern with 155 μm gap is realized on copper plated printed circuit board (PCB). Biocompatible polydimethylsiloxane (PDMS) is used as dielectric as well as hydrophobic layer which is a competitive substitute of expensive materials like Teflon-AF and parylene-C. The device is tested by the in-house developed low cost droplet handling and characterization system. A contact angle is measured by curve fitting; the volume of a droplet is calculated using a novel approach based on mathematical modeling of droplet as a spherical cap. The droplet transporting and merging are successfully performed on a fabricated device and velocities for forward and reverse direction on square and interdigitated pattern are analyzed. The device is also successfully demonstrated for the mixing applications using direct statistical method.