Low-Cost Silver Screen-Printed Electrowetting on Dielectrics Structure for Optofluidic Switches

This work demonstrates a low-cost fabrication method for Electrowetting-on-Dielectric (EWOD) structures for microsystem and Lab-on-a-chip applications. The electrowetting effect allows droplet movement by manipulating the surface tension equilibrium in an EWOD system. A voltage-induced imbalance of the contact angle (CA) at the triple contact line leads to droplet actuation into the direction of the smaller CA. The presented low-cost EWOD stack consists of a suitable substrate, actuation electrodes and dielectric/hydrophobic layers. Screen printed silver electrodes on glass substrates were investigated and characterized. Indium Tin Oxide (ITO) glass slides with a top coated Teflon fluoropolymer were used as electrical counter electrodes. As an application, a demonstrator of a simple optofluidic (OF) switch is simulated in terms of optical path switching time and fabricated using the silver screen printed setup. The incident beam of a laser light source becomes deflected depending on the position of an EWOD actuated droplet inside the device.