Design of on-Chip fluidic devices such as micromixer,
micropump, concentrator and so on are particularly
troublesome, due to viscose effects in micro-scale. We have
studied both the experimental and theoretical effect of AC
electrokinetic mechanism for manipulation of high conductive
fluids. Fluid velocity control was numerically studied by FEAnlysis
to solve the electrical, thermal and fluid mechanic multiphysic
coupled equations. Based on the studies, the efficiency of
ac electrothermal phenomena increases theoretically by
increasing the ionic strength of fluid medium. From experimental
point of view, the Phosphate Buffered Saline is prepared as
carrier fluid with different electrical conductivities and then
seeded with 1 μm sized fluorescent particles to investigate fluid
motion inside a microchannel. An array of asymmetric electrode
pairs were structured on a silicon substrate to generate nonuniform
electric field and induce efficient temperature gradient.
As a result, the fluid motion starts to occur from the narrow
electrodes towards the wide electrodes. Experimental results
confirm that the proposed system is highly efficient for
conductive mediums and the efficiency improves by increasing
both the applied electric field amplitude and frequency. But,
electrochemical reaction and electrode degradation is observed
at very high conductive mediums (above 0.7 S/m). The frequency
behaviour of working fluid is measured by impedance analyser.