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Ionic Current Rectification in a pH-Tunable Polyelectrolyte Brushes Functionalized Conical Nanopore: Effect of Salt Gradient

Lin, Jeng-Yang, Lin, Chih-Yuan, Hsu, Jyh-Ping, Tseng, Shiojenn
Analytical chemistry 2016 v.88 no.2 pp. 1176-1187
brushes, electric field, electrolytes, geometry, nanopores, pH
The behavior of ionic current rectification (ICR) in a conical nanopore with its surface modified by pH-tunable polyelectrolyte (PE) brushes connecting two large reservoirs subject to an applied electric field and a salt gradient is investigated. Parameters including the solution pH, types of ionic species, strength of applied salt gradient, and applied potential bias are examined for their influences on the ionic current and rectification factor, and the mechanisms involved are investigated comprehensively. The ICR behavior depends highly on the charged conditions of the PE layer, the level of pH, the geometry of nanopore, and the thickness of the double layer. In particular, the distribution of ionic species and the local electric field near the nanopore openings play a key role, yielding profound and interesting results that are informative to device design as well as experimental data interpretation.