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Updated: May 23, 2026
09:18
Measurement of Extracellular Ion Fluxes Using the Ion-selective Self-referencing Microelectrode Technique
Published on: May 3, 2015
Dual frequency open-loop electric potential microscopy for local potential measurements in electrolyte solution with
Naritaka Kobayashi1, Hitoshi Asakawa, Takeshi Fukuma
1Frontier Science Organization, Kanazawa University, Kakuma-machi, Kanazawa 920-1192, Japan.
The Review of Scientific Instruments
|April 3, 2012
Summary
A new dual frequency mode for open-loop electric potential microscopy (OL-EPM) allows measurements in strong electrolyte solutions. This advancement expands the application of OL-EPM in biology and chemistry.
Area of Science:
- Electrochemistry
- Surface Science
- Microscopy
Background:
- Open-loop electric potential microscopy (OL-EPM) measures potential at solid/liquid interfaces.
- Conventional OL-EPM is limited to weak electrolyte solutions (<1 mM).
- This limitation restricts its use in biological and chemical applications.
Purpose of the Study:
- To overcome the electrolyte concentration limitation of OL-EPM.
- To develop a new OL-EPM mode for operation in strong electrolyte solutions.
- To enable potential measurements in biologically and chemically relevant environments.
Main Methods:
- Developed dual frequency (DF) mode OL-EPM.
- Applied a dual-frequency ac bias voltage (f(1) and f(2)) between tip and sample.
- Calculated local potential from amplitudes of f(1) and |f(1) - f(2)| components, avoiding 2f(1) detection.
Main Results:
- DF mode OL-EPM operates at higher bias modulation frequencies than single frequency (SF) mode.
- Higher frequencies prevent electrochemical reactions and ion/water redistribution.
- Successfully measured potential distribution of nanoparticles on graphite in 1 and 10 mM NaCl solutions.
Conclusions:
- Dual frequency mode OL-EPM successfully overcomes the electrolyte concentration limitation.
- This technique enables reliable potential measurements in up to 10 mM electrolyte solutions.
- Expands the utility of OL-EPM for interfacial potential studies in diverse chemical and biological systems.
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