Experimental characterization of droplet dispensing in electrowetting-based microfluidics

In this study, the effect of various parameters on the dispensed droplet size in microchannels based on the electrowetting on dielectric technique is experimentally investigated. A printed circuit board (PCB)-based microfluidic chip is used as a platform for the experiments. A crescent configuration for the channel electrodes is fabricated, which leads to a higher electrowetting force which improves the motion of the droplet. In addition, two electrode designs are proposed, which provide a nearly constant overlapping length on the reservoir electrode. The focus of this paper is on the geometry of the reservoir and the channel electrode; therefore, the channel dimensions, surface conditions, and applied voltage are kept constant. The experiments are performed for various reservoir liquid volumes and different electrode shapes of the reservoir and the microchannel. The results show that decreasing the length of the small reservoir electrode reduces the size of the dispensed droplet. It is also observed that using a channel electrode curved in the opposite direction of the droplet motion leads to a smaller dispensed droplet. Published by AIP Publishing.