Publication
562
Anal.
Chem.,74 (24), 6355 -6363, 2002
DOI: 10.1021/ac020385z S0003-2700(02)00385-2 |
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Fabrication of Submicrometer-Sized Gold Electrodes of Controlled
Geometry for Scanning Electrochemical-Atomic Force Microscopy
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Jeremy
Abbou, Christophe Demaile, Michel Druet and Jacques Moiroux
Contribution from the Laboratoire
d'Electrochimie Moléculaire, Université de
Paris 7 - Denis Diderot, Case Courrier 7107, 2 place
Jussieu, 75251 Paris Cedex 05, France . E-mail: demaille@paris7.jussieu.fr
A method for fabricating submicrometer-sized gold electrodes of conical
or spherical geometry is described. By generating an electric arc between
an etched gold microwire and a tungsten counter electrode, the very end
of the gold microwire can be melted and given an overall spherical or
conical shape a few hundred nanometers in size. The whole wire is subsequently
insulated via the cathodic deposition of electrophoretic paint. By applying
a high-voltage pulse to the microwire, the film covering its very end
can then be selectively removed, thus exposing a submicrometer-sized
electrode surface of predefined geometry. The selective exposure of the
preformed end of the microwire is demonstrated by cyclic voltammetry,
scanning electron microscopy, and metal electrodeposition experiments.
The electrophoretic paint coating provides a low-capacitance, robust
insulating film allowing exploration of a very wide potential window
in aqueous solution. The submicrometer-sized electrodes can easily be
turned into probes suitable for combined scanning electrochemical-atomic
force microscopy by bending and flattening the gold microwire so that
the tip is borne by a flexible enough arm. The good agreement between
theoretical and experimental scanning electrochemical microscopy approach
curves thus obtained confirms that only the very end of the tip, of predefined
geometry, is exposed to the solution. |
