title: Characterization of electrode alignment for optimal droplet charging and actuation in droplet-based microfluidic system.
abstract: The actuation method using electric force as a driving force is utilized widely in droplet-based microfluidic systems. In this work, the effects of charging electrode alignment on direct charging of a droplet on electrified electrodes and a subsequent electrophoretic control of the droplet are investigated. The charging characteristics of a droplet according to different electrode alignments are quantitatively examined through experiments and systematic numerical simulations with varying distances and angles between the two electrodes. The droplet charge acquired from the electrified electrode is directly proportional to the distance and barely affected by the angle between the two electrodes. This implies that the primary consideration of electrode alignment in microfluidic devices is the distance between electrodes and the insignificant effect of angle provides a great degree of freedom in designing such devices. Not only the droplet charge acquired from the electrode but also the force exerted on the droplet is analyzed. Finally, the implications and design guidance for microfluidic systems are discussed with an electrophoresis of a charged droplet method-based digital microfluidic device.
authors.affiliation: Department of Chemical Engineering, Pohang University of Science and Technology, Pohang, South Korea.
authors.forename: Myung Mo
authors.initials: MM
authors.lastname: Ahn
authors.affiliation: Department of Chemical Engineering, Pukyong National University, Nam-Gu. Busan, South Korea.
authors.forename: Do Jin
authors.initials: DJ
authors.lastname: Im
authors.affiliation: Department of Chemical Engineering, Pohang University of Science and Technology, Pohang, South Korea.
authors.forename: Byeong Sun
authors.initials: BS
authors.lastname: Yoo
authors.affiliation: Department of Chemical Engineering, Pohang University of Science and Technology, Pohang, South Korea.
authors.forename: In Seok
authors.initials: IS
authors.lastname: Kang
mesh_terms: D003198:Computer Simulation; D004566:Electrodes; D004867:Equipment Design; D046210:Microfluidic Analytical Techniques / Q000295:instrumentation*
keywords: Droplet actuation; Droplet charging; Electrode alignment