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Conductive AFM: Probing Nano-scale Electrical Properties of Model Cell Membranes

Published online by Cambridge University Press:  07 June 2012

Paul Farrar
Affiliation:
School of Engineering and Computing Sciences, Durham University, South Road, Durham, DH1 3LE, UK.
Del Atkinson
Affiliation:
Department of Physics, Durham University, South Road, Durham, DH1 3LE, UK.
Andrew J. Gallant
Affiliation:
School of Engineering and Computing Sciences, Durham University, South Road, Durham, DH1 3LE, UK.
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Abstract

Biologically relevant lipid bilayers supported on highly ordered pyrolytic graphite (HOPG) were probed both mechanically and electrically with a Conductive Atomic Force Microscope (C-AFM) capable of measuring ultra-low currents. Results show that these membranes undergo an elastic response up to 26 nN on average when compressed with an AFM tip. Measuring the films with a low contact force demonstrates that contact mode AFM can be used repeatedly to image without damaging the film. Based on current-voltage measurements made with the C-AFM, it is shown that apparently high resistances seen for the films could be the result of variable electrical contact between the tip and surface. As a result, the paper proposes that the deflection of the cantilever should always be measured in order to ensure knowledge of the location of the tip during all electrical measurements.

Type
Research Article
Copyright
Copyright © Materials Research Society 2012

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References

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