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Abstract
We propose a bi-directional electrohydrodynamic pump developed for transporting dielectric liquid, where the electrodes are symmetrically configured but the applied voltage is non-symmetric. The underlying principle for liquid transport comes from the so-called Onsager effect, which states that the ion concentration is increased as the electric field is increased. Multi-physics software is used to perform numerical simulation for the fluid flow, the electric potential, and the transport of ion concentrations for two kinds of electrode patterns. A flow-visualization experiment is also conducted to verify the physical models and numerical methods employed. It is found that significant reduction of the ion recombination constant is required to get matching of the experimental and simulation results. We demonstrate through a parametric study that there is an optimum distance between two large grounded electrodes for producing a maximum pumping velocity at the diameter of two small electrodes fixed at 0.3 mm. The effect of the size of large grounded electrodes on the pumping performance is also studied in terms of streamlines, electric field, and charge distribution. A general account is also given of the basic ideas of electrode arrangement for the enhancement of pumping.
Keywords
Electrohydrodynamic pump, bi-directional pump, dielectric liquid, Onsager effect
Date received: 6 July 2015; accepted: 29 May 2016
Academic Editor: Bo Yu
(ProQuest: ... denotes formulae omitted.)
Introduction
How to pump fluids in the transport system of miniand micro-scales has become a very important issue. In a lab-on-chip or micro-total analysis system ( m TAS), for instance, the liquid sample must be transported from the inlet reservoir to the places where mixing and chemical reaction of samples and detection of the outcome take place.1-4 In electronic devices, due to the trend of miniaturization, a more efficient and powerful but small-size pump is demanded for the cooling of electronic components5-7 or power electronics.8,9 Mechanically actuated pumps are seldom used because of difficulty in fabrication, flow control, and so on. Electrokinetic pumping then emerges as a practical way to achieve fluid transport in view of its simple structure, ease of fabrication, and controllability. Aside from its compatibility, the electrokinetic method is susceptible to electrode degradation and bubble generation through electrolysis when a polar liquid with high permittivity, such as water, is to be pumped.10 Various...