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Interference of electrochemical ion diffusion in nanopore sensing
Iat Wai Leong1, Shohei Kishimoto1, Makusu Tsutsui1
1The Institute of Scientific and Industrial Research, Osaka University, Mihogaoka 8-1, Ibaraki, Osaka 567-0047, Japan.
Iscience
|September 23, 2022
Summary
Ion diffusion at liquid-electrode interfaces slows nanopore sensing. This study reveals how electrode impedance and capacitance degrade ionic current measurements, impacting nanoparticle and molecule analysis.
Area of Science:
- Electrochemistry
- Nanotechnology
- Analytical Chemistry
Background:
- Stable ionic current is crucial for nanopore sensing of small objects.
- Ion diffusion kinetics at liquid-electrode interfaces can interfere with measurements.
Purpose of the Study:
- To investigate the interference of ion diffusion kinetics at liquid-electrode interfaces in nanopore sensing.
- To understand how electrode properties affect ionic current measurements and temporal resolution.
Main Methods:
- Utilized platinum electrodes in a salt solution with a nanopore.
- Measured ionic current and analyzed changes in interfacial impedance.
- Investigated the coupling between interfacial impedance and nanopore chip capacitance.
Main Results:
- Observed a slow, large decrease in ionic current due to growing impedance at liquid-metal interfaces (Cottrell diffusion).
- Resistive pulses from nanoparticle detection weakened due to increased electrode resistance.
- Interfacial impedance coupled with capacitance, degrading temporal resolution of ionic current measurements.
Conclusions:
- Interfacial ion diffusion significantly impacts nanopore sensing accuracy and speed.
- Electrode material and size are critical factors for optimizing single-particle and single-molecule analysis.
- Understanding these interfacial effects is key to improving nanopore sensing technologies.
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