Surface Charge Density Determination of Single Conical Nanopores Based on Normalized Ion Current Rectification

Department of Chemistry, Georgia State University, Atlanta, Georgia 30302, USA.
Langmuir (Impact Factor: 4.46). 12/2011; 28(2):1588-95. DOI: 10.1021/la203106w
Source: PubMed


Current rectification is well known in ion transport through nanoscale pores and channel devices. The measured current is affected by both the geometry and fixed interfacial charges of the nanodevices. In this article, an interesting trend is observed in steady-state current-potential measurements using single conical nanopores. A threshold low-conductivity state is observed upon the dilution of electrolyte concentration. Correspondingly, the normalized current at positive bias potentials drastically increases and contributes to different degrees of rectification. This novel trend at opposite bias polarities is employed to differentiate the ion flux affected by the fixed charges at the substrate-solution interface (surface effect), with respect to the constant asymmetric geometry (volume effect). The surface charge density (SCD) of individual nanopores, an important physical parameter that is challenging to measure experimentally and is known to vary from one nanopore to another, is directly quantified by solving Poisson and Nernst-Planck equations in the simulation of the experimental results. The flux distribution inside the nanopore and the SCD of individual nanopores are reported. The respective diffusion and migration translocations are found to vary at different positions inside the nanopore. This knowledge is believed to be important for resistive pulse sensing applications because the detection signal is determined by the perturbation of the ion current by the analytes.

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Available from: Jingyu Feng, Apr 22, 2015
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    • "The ability to control the ion transport, which is highly dependent on surface charge properties and ion concentration distributions [1] [2], in nanofluidics such as nanochannels and nanopore plays a key role for emerging applications such as energy harvesting [3] [4], rectification of ion current [5] [6] [7], and sensing and analyzing of (bio)nanoparticles [8] [9] [10]. To achieve active control, nanofluidic field effect transistors (FETs) [11] [12], referring to gate electrode-embedded nanofluidic devices, have been developed recently. "
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