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Method to determine the effective ζ potential in a microchannel with an embedded gate electrode
Author(s) -
Lenzi Alessio,
Viola Francesco,
Bonotto Francesco,
Frey Jared,
Napoli Maria,
Pennathur Sumita
Publication year - 2011
Publication title -
electrophoresis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.666
H-Index - 158
eISSN - 1522-2683
pISSN - 0173-0835
DOI - 10.1002/elps.201100262
Subject(s) - microchannel , zeta potential , electrode , materials science , channel (broadcasting) , surface charge , displacement (psychology) , microfluidics , analytical chemistry (journal) , biological system , optoelectronics , chemistry , mechanics , nanotechnology , computer science , physics , chromatography , psychology , computer network , nanoparticle , psychotherapist , biology
We present a theoretical model to determine the effective zeta potential ζ eff in microfluidic channels where an embedded, insulated gate electrode allows for external tuning of a portion of the channel surface charge. In addition, we derive a method to determine ζ eff in such channels, for any value of salt concentration, using the solution displacement technique. To do so, we simulate typical current‐monitoring measurements using our model, and highlight the experimental parameters that lead to inaccurate results using this procedure with an heterogenous channel. Our method corrects for such inaccuracies by using our model with experimental data to find the correct value of ζ eff . Finally, we perform experiments to demonstrate our method and the use of our model with a silica‐PMDS microchannel system with an embedded Ti‐Au‐Ti gate electrode that covers 50% of the bottom surface of the channel. We show that our theory captures the salient features of our experiments, thereby offering a useful tool to predict effective zeta potential in channels with a nonuniform zeta potential.