Streaming currents in microfluidics with integrated polarizable electrodes

Autor: V. Chu, João Pedro Conde, D. C. Martins, Duarte M. F. Prazeres
Rok vydání: 2013
Předmět:
Zdroj: Microfluidics and Nanofluidics. 15:361-376
ISSN: 1613-4990
1613-4982
DOI: 10.1007/s10404-013-1153-5
Popis: A surface in contact with an aqueous solution is electrically characterized by the zeta potential. One way of determining indirectly the zeta potential of a surface is by measuring the streaming currents generated by a Poiseuille flow through a capillary channel with charged walls. We report measurements of streaming current in individual rectangular glass/PDMS microchannels with integrated miniaturized electrodes. Experiments performed using solutions with different salt concentrations and different electrode materials showed that the measured electrical current depends on the electrode material and in general differs from the real value of the streaming current. To determine the streaming current from the experimental data, an equivalent circuit model is proposed. The extracted value of the streaming current is proportional to the flow rate of electrolyte and the calculated glass/PDMS zeta potential scales linearly with the logarithm of the salt concentration. This work offers a thorough analysis of the effects that come into play during streaming current measurements and, in particular, it describes potential sources of error that can affect the streaming current measurements and suggestions on how to correct the measured values.
Databáze: OpenAIRE