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Electrowetting Using a Microfluidic Kelvin Water Dropper

Department of Mechanical & Aerospace Engineering, Old Dominion University, Norfolk, VA 23529, USA
State Key Lab of Mechanics and Control of Mechanical Structures, Nanjing University of Aeronautics & Astronautics, Nanjing, Jiangsu 210016, China
Author to whom correspondence should be addressed.
Micromachines 2018, 9(3), 92;
Received: 16 December 2017 / Revised: 15 February 2018 / Accepted: 22 February 2018 / Published: 25 February 2018
(This article belongs to the Special Issue Micro/Nano-Chip Electrokinetics, Volume II)
PDF [1677 KB, uploaded 26 February 2018]


The Kelvin water dropper is an electrostatic generator that can generate high voltage electricity through water dripping. A conventional Kelvin water dropper converts the gravitational potential energy of water into electricity. Due to its low current output, Kelvin water droppers can only be used in limited cases that demand high voltage. In the present study, microfluidic Kelvin water droppers (MKWDs) were built in house to demonstrate a low-cost but accurately controlled miniature device for high voltage generation. The performance of the MKWDs was characterized using different channel diameters and flow rates. The best performed MKWD was then used to conduct experiments of the electrowetting of liquid on dielectric surfaces. Electrowetting is a process that has been widely used in manipulating the wetting properties of a surface using an external electric field. Usually electrowetting requires an expensive DC power supply that outputs high voltage. However, in this research, it was demonstrated that electrowetting can be conducted by simply using an MKWD. Additionally, an analytic model was developed to simulate the electrowetting process. Finally, the model’s ability to well predict the liquid deformation during electrowetting using MKWDs was validated. View Full-Text
Keywords: microfluidic Kelvin water dropper; high voltage; COMSOL; electrowetting microfluidic Kelvin water dropper; high voltage; COMSOL; electrowetting

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This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited (CC BY 4.0).

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Yazdanshenas, E.; Tang, Q.; Zhang, X. Electrowetting Using a Microfluidic Kelvin Water Dropper. Micromachines 2018, 9, 92.

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