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Issue 11, 2012
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Quantification of noise sources for amperometric measurement of quantal exocytosis using microelectrodes

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Abstract

Electrochemical microelectrodes are commonly used to record amperometric spikes of current that result from oxidation of transmitter released from individual vesicles during exocytosis. Whereas the exquisite sensitivity of these measurements is well appreciated, a better understanding of the noise sources that limit the resolution of the technique is needed to guide the design of next-generation devices. We measured the current power spectral density (SI) of electrochemical microelectrodes to understand the physical basis of dominant noise sources and to determine how noise varies with the electrode material and geometry. We find that the current noise is thermal in origin in that SI is proportional to the real part of the admittance of the electrode. The admittance of microelectrodes is well described by a constant phase element model such that both the real and imaginary admittance increase with frequency raised to a power of 0.84–0.96. Our results demonstrate that the current standard deviation is proportional to the square root of the area of the working electrode, increases ∼linearly with the bandwidth of the recording, and varies with the choice of the electrode material with Au ≈ carbon fiber > nitrogen-doped diamond-like carbon > indium-tin-oxide. Contact between a cell and a microelectrode does not appreciably increase noise. Surface-patterned microchip electrodes can have a noise performance that is superior to that of carbon-fiber microelectrodes of the same area.

Graphical abstract: Quantification of noise sources for amperometric measurement of quantal exocytosis using microelectrodes

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Publication details

The article was received on 03 Feb 2012, accepted on 11 Apr 2012 and first published on 13 Apr 2012


Article type: Paper
DOI: 10.1039/C2AN35157A
Citation: Analyst, 2012,137, 2674-2681
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    Quantification of noise sources for amperometric measurement of quantal exocytosis using microelectrodes

    J. Yao and K. D. Gillis, Analyst, 2012, 137, 2674
    DOI: 10.1039/C2AN35157A

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