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Modulation of Ionic Current Rectification in Ultrashort Conical Nanopores
Long Ma1, Zhongwu Li2, Zhishan Yuan3
1Key Laboratory of High Efficiency and Clean Mechanical Manufacture of Ministry of Education, National Demonstration Center for Experimental Mechanical Engineering Education, School of Mechanical Engineering, Shandong University, Jinan 250061, China.
Analytical Chemistry
|November 20, 2020
Summary
Ionic current rectification (ICR) in ultrashort nanopores can be precisely controlled by tuning charged surfaces. This research demonstrates how to engineer ICR in conical nanopores under 200 nm for advanced nanofluidic applications.
Area of Science:
- Nanotechnology
- Physical Chemistry
- Materials Science
Background:
- Ionic current rectification (ICR) enables nanopores to function as diodes, directing ion flow.
- Significant ICR typically requires nanopore lengths of at least 500 nm.
- Short conical nanopores (<200 nm) have shown limited ICR, hindering their application.
Purpose of the Study:
- To investigate the mechanism of ICR in ultrashort conical nanopores (<200 nm).
- To demonstrate how controlling charged surfaces can tune ICR in these short nanopores.
- To provide design guidelines for engineering ultrashort conical nanopores for nanofluidic devices.
Main Methods:
- Utilized the finite element method to simulate ion transport and ICR.
- Analyzed the impact of charged inner pore surfaces (surfaceinner) and exterior tip/base surfaces (surfacetip, surfacebase).
- Investigated the effects of varying charge distribution and depth on ICR.
Main Results:
- ICR in ultrashort conical nanopores can be effectively tuned by surface charges, particularly surfaceinner and surfacetip.
- Surfaceinner alone can induce significant ICR and ion concentration polarization, leading to reverse rectification.
- Combinations of charged surfaces yield tunable ICR ratios from ~2 to ~170, with additive effects on ion concentration regulation.
Conclusions:
- Surface charge engineering is a viable strategy to achieve significant ICR in ultrashort conical nanopores.
- The findings elucidate the underlying mechanisms of ICR in sub-200 nm conical nanopores.
- This work offers a pathway for designing and modifying ultrashort nanopores for ionic circuits and nanofluidic sensors.
