Date of Award
Spring 2011
Document Type
Thesis
Degree Name
Master of Science (MS)
Department
Mechanical & Aerospace Engineering
Program/Concentration
Aerospace Engineering
Committee Director
Shizhi Qian
Committee Member
Robert L. Ash
Committee Member
Yan Peng
Call Number for Print
Special Collections; LD4331.E535 B35 2011
Abstract
The magnitude of current through a conical nanopore filled with an electrolyte solution depends on the polarity of the applied bias, indicating an asymmetric diode-like current-voltage (I-V) curve. This kind of phenomenon refers to ionic current rectification (ICR), which is of interest because many ion-channel proteins in cellular membranes are rectifying. In addition, ICR in nanopores can be used to control ion concentrations in nano- and microfluidic systems. In this study, the ICR phenomenon through a conical nanopore simultaneously subjected to an electric field and salt concentration gradient is experimentally and numerically investigated.
The experiments were conducted in an Izon's SIOS nanopore system, which consisted of a fluid cell with two fluid wells separated by a thermoplastic polyurethane membrane containing a single conical nanopore. The ICR was studied experimentally by imposing a bias voltage ranging from -IV to IV across the two fluid wells filled with potassium chloride (KCI) solutions of two different concentrations. To elucidate the mechanism of ICR, a mathematical model consisting of the Nernst - Planck equations for the ionic mass transport, the Poisson equation for the electrostatics, and the Navier- Stokes equations for the flow field has been developed. The obtained numerical results are in qualitative agreement with the obtained experimental results.
In this research, the effect of the imposed electrolyte concentration gradient on the ICR is studied for the first time. Typically, the preferential current direction of a negatively charged nanopore directs from the tip towards the base due to the ion depletion under a negative voltage and ion enrichment under a positive voltage. Furthermore, the preferential current direction of a nanopore highly depends on the externally imposed salt concentration gradient, which makes it possible to tune ICR by altering the salt concentrations in the two fluid reservoirs.
Rights
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DOI
10.25777/7c0f-ev46
Recommended Citation
Bakirci, Murat.
"Ionic Current Rectification Phenomena in Asymmetrical Polymer Nanopores Under Salt Gradients"
(2011). Master of Science (MS), Thesis, Mechanical & Aerospace Engineering, Old Dominion University, DOI: 10.25777/7c0f-ev46
https://digitalcommons.odu.edu/mae_etds/408