ELECTROCHEMICAL NANOFABRICATIONS: A GENERAL REVIEW - Electrochemical Nanofabrication: Principles and Applications - page 21

between tool and workpiece. Examples of patterns made with the
2×2 array of cubes tool are shown in Fig. 1. 9b . This indicates that the
feature resolution improves with decrease in pulse duration.

Figure 1.9 Scanning electron micrographs. (a) Tungsten tool;

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(b) machined Ni substrate. Experimental conditions: U = 1.7 V, U

tool

=

sub

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1.0 V, pulse duration indicated, 2 V amplitude, 1:10 pulse to pause
ratio, and 0.2 M HCl electrolyte. Feature resolution and edge sharpness
increased as pulse duration decreased [114]. Reproduced by kind
permission from the publisher.

3D machining of electrochemically active materials, including
the construction of unconventional island patterns on a surface
with nanoscale resolution, was also realized by this method
[95,115-117]. Thus, electrochemical machining can be applied to
microelectromechanical systems (MEMS) [118] and even in the
nanoelectromechanical systems (NEMS). Electrochemical methods
can realize the nanofabrication in a selective place and make the
complicated 3D nanostructures. Conducting polymers can also be
fabricated in this way. Similar to the electrochemical machining,
by application of short voltage pulses to the tool electrode in the
vicinity of the workpiece electrode, the electropolymerization of
pyrrole can be locally confined with micrometer precision [119]. As
the produced nuclei of conducting polymers will grow preferentially
vertically to the surface, fiber-like morphologies were found in