title: Transient zeta-potential measurements in hydrophobic, TOPAS microfluidic substrates.
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 zeta-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 zeta-potential as inferred through current monitoring experiments was constant in time. No electrokinetic transients were observed in silica microchannels under these flow conditions.
authors.affiliation: Department of Biomedical Engineering, Cornell University, Ithaca, NY 14853, USA.
authors.forename: Vishal
authors.initials: V
authors.lastname: Tandon
authors.forename: Sharath K
authors.initials: SK
authors.lastname: Bhagavatula
authors.forename: Brian J
authors.initials: BJ
authors.lastname: Kirby
mesh_terms: D055590:Electromagnetic Phenomena; D053841:Electroosmosis / Q000379:methods*; D000431:Ethanol / Q000737:chemistry; D057927:Hydrophobic and Hydrophilic Interactions; D046210:Microfluidic Analytical Techniques / Q000379:methods*; D012822:Silicon Dioxide / Q000737:chemistry
chemical_list: D000431:Ethanol; D012822:Silicon Dioxide