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Journal Article

ac-field-induced fluid pumping in microsystems with asymmetric temperature gradients


Holtappels,  M.
Department of Biogeochemistry, Max Planck Institute for Marine Microbiology, Max Planck Society;

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Holtappels, M., Stubbe, M., & Gimsa, J. (2009). ac-field-induced fluid pumping in microsystems with asymmetric temperature gradients. Physical Review E, 79(2): 026309.

Cite as: http://hdl.handle.net/21.11116/0000-0001-CC7C-F
We present two different designs of electrohydrodynamic micropumps for microfluidic systems. The micropumps have no movable parts, and their simple design allows for fabrication by microsystems technology. The pumps are operated by ac voltages from 1to60V and were tested with aqueous solutions in the conductivity range of 1–112mSm−1. The pump effect is induced by an ac electric field across a fluid medium with an inhomogeneous temperature distribution. It is constant over a wide range of the ac field frequency with a conductivity-dependent drop-off at high frequencies. The temperature-dependent conductivity and permittivity distributions in the fluid induce space charges that interact with the electric field and induce fluid motion. The temperature distribution can be generated either by Joule heating in the medium or by external heating. We present experimental results obtained with two prototypes featuring Joule heating and external heating by a heating filament. Experimental and numerical results are compared with an analytical model.