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 mu m 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.