New publication: Transient ζ-potential measurements in hydrophobic, TOPAS microfluidic substrates
Transient ζ-potential measurements in hydrophobic, TOPAS microfluidic substrates
Vishal Tandon, Sharath K. Bhagavatula, Brian J. Kirby
ELECTROPHORESIS
Volume 30, Issue 15, pages 2656–2667, August 2009, DOI: 10.1002/elps.200900028
Keywords:
- Electrokinetic;
- Electroosmosis;
- Hydrophobic;
- Transient;
- ζ-potential
Abstract
We utilize time-resolved electrokinetic measurements in order to study the electrokinetic properties of silica and TOPAS microfluidic channels as a function of the time history of the fluid–solid interface. In pressure-driven flow through TOPAS microchannels, the ζ-potential as inferred from streaming potential measurements decays exponentially by a factor of 1.5 with a characteristic decay time of 3 h after the initial formation of the fluid–solid interface. A similar exponential decay is observed immediately after water is exchanged for ethanol as the solvent in the system. In electroosmotically driven flow through TOPAS microchannels, the ζ-potential as inferred through current monitoring experiments was constant in time. No electrokinetic transients were observed in silica microchannels under these flow conditions.