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Scanning ion conductance microscopy: a model for experimentally realistic conditions and image interpretation
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Edwards, Martin A., Williams, Cara G., Whitworth, Anna L. and Unwin, Patrick R. (2009) Scanning ion conductance microscopy: a model for experimentally realistic conditions and image interpretation. Analytical Chemistry, Vol.81 (No.11). pp. 4482-4492. doi:10.1021/ac900376w ISSN 0003-2700.
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Official URL: http://dx.doi.org/10.1021/ac900376w
Abstract
Scanning ion conductance microscopy (SICM) is a scanned probe microscopy technique in which the probe is a fine glass pipet filled with a contact (reference) electrode and an electrolyte solution. The current flow between the reference electrode and a second reference electrode positioned in bulk solution when the two electrodes are biased externally can be used as a feedback signal to maintain a constant separation between the tip and a surface during imaging. In usual practice the tip position is modulated over a small amplitude perpendicular to the surface, and the resulting alternating current (AC) is used as the feedback signal, although the direct current can also be used. A comprehensive model for the current response is reported. Laplace's equation has been solved for the electrolyte solution for a range of tip geometries, enabling the factors controlling the tip current to be identified. The approach developed is shown to represent an improvement over earlier semiempirical treatments. To explore the influence of surface topography on the (AC) current response, various surfaces have been considered, including a tip moved toward a planar surface (in the normal direction) and tips scanned over a pit and a step in the surface. The results have allowed a critical assessment of the SICM response as a means of probing surface topography. Features identified through simulation have been found in experiments through studies of two model substrates for which imaging results are reported. In typical experimental practice, the response of the SICM tip to surface features occurs over much greater lateral distances than the size of the pipet aperture.
Item Type: | Journal Article | ||||
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Subjects: | Q Science > QD Chemistry | ||||
Divisions: | Faculty of Science, Engineering and Medicine > Science > Chemistry Faculty of Science, Engineering and Medicine > Research Centres > Molecular Organisation and Assembly in Cells (MOAC) |
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Journal or Publication Title: | Analytical Chemistry | ||||
Publisher: | American Chemical Society | ||||
ISSN: | 0003-2700 | ||||
Official Date: | 1 June 2009 | ||||
Dates: |
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Volume: | Vol.81 | ||||
Number: | No.11 | ||||
Number of Pages: | 11 | ||||
Page Range: | pp. 4482-4492 | ||||
DOI: | 10.1021/ac900376w | ||||
Status: | Peer Reviewed | ||||
Publication Status: | Published | ||||
Access rights to Published version: | Restricted or Subscription Access | ||||
Funder: | Engineering and Physical Sciences Research Council (EPSRC), GlaxoSmithKline |
Data sourced from Thomson Reuters' Web of Knowledge
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