Enhanced ac electrothermal fluidic pumping in microgrooved channels

It is important to generate fast fluid flow yet maintain low ternperature rise for ac electrothermal (ac ET) pumping in microsystems with conductive fluids. This has been generally the limitation of ac ET driven micropump applications. We present an enhanced ac ET pumping mechanism using low voltage ac signals that can result in a small amount of temperature rise. Different from the published traveling wave and asymmetric electrode structures positioned on insulated flat surfaces, channels with a microgrooved surface are utilized in this study. The effects of the microgroove existence on the modification of the ET body force and recession of the vortex backflows are demonstrated. Forward and backward pumping modes are identified and analyzed. This mechanism utilizes a thin film of asymmetric electrode structure on the microgrooved channel floor that can be fabricated with common planar lithography technologies. This study demonstrates that using the microgrooved structure can increase pumping capacity by five to sixfold as compared to a planar electrode arrangement with the same effective dimensions. (C) 2008 American Institute of Physics. [DOI: 10.1063/1.2977617]