Surface Charge Density Determination of Single Conical Nanopores Based on Normalized Ion Current Rectification
- Georgia State Univ., Atlanta, GA (United States). Dept. of Chemistry
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 paper, 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 degree of rectification. The novel opposite 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, are directly quantified by solving Poisson and Nernst-Planck equations in the simulation of the experimental results. Flux distribution inside the nanopore and SCD of individual nanopores are reported. The respective diffusion and migration translocations are found to vary at different positions inside the nanopore. The knowledge is believed important for resistive pulse sensing applications, as the detection signal is determined by the perturbation of ion current by the analytes.
- Research Organization:
- Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC), Basic Energy Sciences (BES)
- DOE Contract Number:
- AC05-00OR22725
- OSTI ID:
- 1033178
- Journal Information:
- Langmuir, Vol. 28, Issue 2; ISSN 0743-7463
- Publisher:
- American Chemical Society
- Country of Publication:
- United States
- Language:
- English
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