(503b) Adapting Current Monitoring Measurements to Low Conductivity Systems

Current monitoring is a well-known technique to characterize electroosmotic flow (EOF) in microfluidic devices. The method relies on a dynamic transition in the measured current when a solution is replaced by a second solution, having a different concentration, under the application of an external electric field. The concentration difference defines the current signal to be measured: larger differences result in a larger signal. A small difference in concentration is employed, however, to avoid the dispersion in the solutions interface, which results in internal pressure generation. In the cases where the EOF is slow, the signal to measure further decreases and the complete replacement of the original solution may take a long time to migrate; in consequence, the estimation of an accurate electroosmotic mobility becomes challenging. This work, based on the use of the Y-channel proposed by Almutairi et al. [1], presents an alternative approach where all available experimental information is used to effectively estimate the electroosmotic mobility when the EOF is small.

References:

1.            Almutairi, Z., et al., A Y-channel design for improving zeta potential and surface conductivity measurements using the current monitoring method. Microfluidics and Nanofluidics, 2009. 6(2): p. 241-251.