29 June 2005 AC electrokinetic pumping of liquids using arrays of microelectrodes
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The precise control and manipulation of small masses of liquids is an important requirement in the lab-on-a-chip technology. Net fluid flows induced by ac potentials applied to arrays of co-planar interdigitated microelectrodes are reported. Two types of microelectrode structures have been studied: arrays of unequal width electrodes subjected to a single ac signal, and arrays of identical electrodes subjected to a travelling-wave potential. Experiments were performed using solutions of KCl in water of conductivities around 1mS/m placed on top of the electrodes. Fluorescent latex particles were used as tracers. In both microstructures, two fluid flow regimes have been observed: at small voltage amplitudes the fluid moves in a certain direction, and at higher voltage amplitudes the fluid flow is reversed. The fluid flow seems to be driven at the level of the electrodes in the two regimes. A theoretical model of ac electroosmosis is described. The model is based upon the Gouy-Chapman-Stern theory of the double layer. The theoretical results are in qualitative accordance with the experimental observations at low voltages.
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Antonio Ramos, Antonio Ramos, Pablo Garcia, Pablo Garcia, Antonio Gonzalez, Antonio Gonzalez, Antonio Castellanos, Antonio Castellanos, Hywel Morgan, Hywel Morgan, Nicolas G. Green, Nicolas G. Green, "AC electrokinetic pumping of liquids using arrays of microelectrodes", Proc. SPIE 5839, Bioengineered and Bioinspired Systems II, (29 June 2005); doi: 10.1117/12.608236; https://doi.org/10.1117/12.608236

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