Streaming Potential Revisited: The Influence of Convection
on the Surface Conductivity
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Abstract
Electrokinetic
phenomena play an important role in the electrical
characterization of surfaces. In terms of planar or porous substrates,
streaming potential and/or streaming current measurements can be used
to determine the zeta potential of the substrates in contact with
aqueous electrolytes. In this work, we perform electrical impedance
spectroscopy measurements to infer the electrical resistance in a
microchannel with the same conditions as for a streaming potential
experiment. Novel correlations are derived to relate the streaming
current and streaming potential to the Reynolds number of the channel
flow. Our results not only quantify the influence of surface conductivity,
and here especially the contribution of the stagnant layer, but also
reveal that channel resistance and therefore zeta potential are influenced
by the flow in the case of low ionic strengths. We conclude that convection
can have a significant impact on the electrical double layer configuration
which is reflected by changes in the surfaces conductivity