Effect of Conical Nanopore Diameter on Ion Current Rectification

Kovarik, Michelle L.; Zhou, Kaimeng; Jacobson, Stephen C.

doi:10.1021/jp9076189

Cited by 176 publications

(195 citation statements)

References 45 publications

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“…As expected, these nanopipettes show slight ICR due to the negative surface charge at the walls of the nanopipette, 21,22 with the current magnitude at positive values of the applied potential (V QRCE, nanopipette -V QRCE, bulk ) being less than the current magnitude at negative potential values, as discussed in some detail in the literature, 19,20,22,38,39 and briefly below. The additional effect of a charged surface on the DC and AC ion currents in SICM is investigated herein.…”

Section: Resultssupporting

confidence: 68%

Surface Charge Mapping with a Nanopipette

et al. 2014

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Nanopipettes are emerging as simple but powerful tools for probing chemistry at the nanoscale.In this contribution the use of nanopipettes for simultaneous surface charge mapping and topographical imaging is demonstrated, using a scanning ion conductance microscopy (SICM) format. When a nanopipette is positioned close to a surface in electrolyte solution the direct ion current (DC), driven by an applied bias between a quasi-reference counter electrode (QRCE) in the nanopipette and a second QRCE in the bulk solution is sensitive to surface charge. The charge sensitivity arises because the diffuse double layers at the nanopipette and the surface interact, creating a perm-selective region which becomes increasingly significant at low ionic strengths (10 mM 1:1 aqueous electrolyte herein). This leads to a polarity-dependent ion current and surface-induced rectification as the bias is varied. Using distance-modulated SICM, which induces an alternating ion current component (AC) by periodically modulating the distance between the nanopipette and the surface, the effect of surface charge on the DC and AC is explored and rationalized. The impact of surface charge on the AC phase (with respect to the driving sinusoidal signal) is highlighted in particular; this quantity shows a shift that is highly sensitive to interfacial charge and provides the basis for visualizing charge simultaneously with topography. The studies herein highlight the use of nanopipettes for functional imaging with applications from cell biology to materials characterization where understanding surface charge is of key importance.3

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Section: Resultssupporting

confidence: 68%

Surface Charge Mapping with a Nanopipette

et al. 2014

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“…The proposed molecular theory and numerical simulation have predicted that tailoring charges on the exterior surfaces could induce the rectified ionic transport in a nanopore or nanochannel 7. As reported, the charged exterior surface has a similar electrostatic influence as charged interior one on the mobile ions at the entrance of nanopore/channel, and thus affect the ion conductance 8.…”

Section: Introductionmentioning

confidence: 78%

Robust Sandwich‐Structured Nanofluidic Diodes Modulating Ionic Transport for an Enhanced Electrochromic Performance

et al. 2018

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Biomimetic solid‐state nanofluidic diodes have attracted extensive research interest due to the possible applications in various fields, such as biosensing, energy conversion, and nanofluidic circuits. However, contributions of exterior surface to the transmembrane ionic transport are often ignored, which can be a crucial factor for ion rectification behavior. Herein, a rational design of robust sandwich‐structured nanofluidic diode is shown by creating opposite charges on the exterior surfaces of a nanoporous membrane using inorganic oxides with distinct isoelectric points. Potential‐induced changes in ion concentration within the nanopores lead to a current rectification; the results are subsequently supported by a theoretical simulation. Except for providing surface charges, functional inorganic oxides used in this work are complementary electrochromic materials. Hence, the sandwich‐structured nanofluidic diode is further developed into an electrochromic membrane exhibiting a visual color change in response to redox potentials. The results show that the surface‐charge‐governed ionic transport and the nanoporous structure facilitate the migration of Li+ ions, which in turn enhance the electrochromic performance. It is envisioned that this work will create new avenues to design and optimize nanofluidic diodes and electrochromic devices.

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“…Observing rectification behavior in 0.1 M KCl for a pore with an opening diameter of 6 nm might seem surprising, but experimental data of rectified ion current for even wider pores were reported 50 . According to the classical Debye-Hueckel theory, the thickness of the electrical double-layer is in this case only ≈ 1 nm, thus the majority of the pore cross-section should be filled with bulk electrolyte.…”

Section: Influence Of the Surface Charge On The Rectification Behaviormentioning

confidence: 99%

Rectification properties of conically shaped nanopores: consequences of miniaturization

Pietschmann

Wolfram

Burger

et al. 2013

Phys. Chem. Chem. Phys.

116

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Nanopores attracted a great deal of scientific interest as templates for biological sensors as well as model systems to understand transport phenomena at the nanoscale. The experimental and theoretical analysis of nanopores has been so far focused on understanding the effect of the pore opening diameter on ionic transport. In this article we present systematic studies on the dependence of ion transport properties on the pore length. Particular attention was given to the effect of ion current rectification exhibited for conically shaped nanopores with homogeneous surface charges. We found that reducing the length of conically shaped nanopores significantly lowered their ability to rectify ion current. However, rectification properties of short pores can be enhanced by tailoring the surface charge and the shape of the narrow opening. Furthermore we analyze the relationship of the rectification behavior and ion selectivity for different pore lengths. All simulations were performed using MsSimPore, a software package for solving the Poisson-Nernst-Planck (PNP) equations. It is based on a novel finite element solver and allows for simulations up to surface charge densities of -2 e/nm 2 . MsSimPore is based on 1D reduction of the PNP model, but allows for a direct treatment of the pore with bulk electrolyte reservoirs, a feature which was previously used in higher dimensional models only. MsSimPore includes these reservoirs in the calculations; a property especially important for short pores, where the ionic concentrations and the electric potential vary strongly inside the pore as well as in the regions next to pore entrance.

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Effect of Conical Nanopore Diameter on Ion Current Rectification

Cited by 176 publications

References 45 publications

Surface Charge Mapping with a Nanopipette

Surface Charge Mapping with a Nanopipette

Robust Sandwich‐Structured Nanofluidic Diodes Modulating Ionic Transport for an Enhanced Electrochromic Performance

Rectification properties of conically shaped nanopores: consequences of miniaturization

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