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TitleConductive and biphasic pulses in tunable resistive pulse sensing
Publication TypeJournal Article
Year of Publication2015
AuthorsWeatherall, E., and Willmott G.R.
JournalJournal of Physical Chemistry B
Pagination5328 - 5335
Date Published2015
ISSN15206106 (ISSN)
KeywordsApplied voltages, Carboxylation, Colloids, Electrolyte concentration, Electrolytes, Experimental conditions, Ionic concentrations, Particle measurement, Phosphate-buffered salines, Polystyrene spheres, Pore size, Resistive pulse sensing
AbstractThis experimental study concerns the occurrence of biphasic pulses generated during tunable resistive pulse sensing (TRPS) of 200 nm carboxylate polystyrene spheres. In TRPS, a short-lived pulse in ionic current is observed when an individual colloid passes through a pore which separates two fluid reservoirs. The pulse is conventionally resistive, but conductive pulses are observed under certain experimental conditions, as well as biphasic pulses which include both resistive and conductive components. The experimental variables investigated here include the concentration of the phosphate-buffered saline electrolyte, particle charge, pore size, applied voltage, and the direction of particle motion. The onset upper electrolyte concentration for biphasic pulses in TRPS is ∼50 mM, and the ordering of biphasic pulse components can be interpreted using ionic concentration polarization if the conductive component is generated when the particle is in the ion depletion region. Besides providing fundamental understanding, the results are important for the TRPS technique, which is becoming widely used for particle-by-particle measurements of submicron colloids. © 2015 American Chemical Society.

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