Biomedical Engineering Reference
In-Depth Information
100
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3.53 mW
50
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3.28 mW
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50
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100
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Fig. 3.26. Example of scanning thermal microscopy. Thermal conductivity image of a section from
a glass filament/cyanate resin composite. The glass fibres clearly show greater thermal conductivity
than the polymer matrix. Reproduced from [238] with permission.
discrimination of buried features [232]. This mode also allows for the imaging of heat
capacity [231]. In addition to the imaging-type experiments, it is possible to perform
many typical thermal analysis experiments using a similar set-up such as localized
calorimetry or thermo-mechanical analysis [233-236]. The aim of all these techniques
is to characterize materials thermally on the nanoscale. As such most of these experi-
ments could be performed macroscopically on whole samples much more easily, so the
main application is in heterogeneous materials. As well as specialized probes, SThM
requires some simple external circuitry, and so its adoption as a standard AFM technique
has not been widespread. However, such probes are commercially available, and the
technique gives information not available by other means, so a large number of studies
have been applied to polymer composites [237-239]; in addition, micro-organisms
[231], pharmaceuticals [232, 236, 240], automotive coatings [241], metal alloys [242]
and electronic devices [243] have been studied with SThM. The interested reader is
directed to an excellent review for more information on this technique [231].
As well as measuring sample surfaces, an AFM may be used to manipulate or to modify
the surfaces. The fine control of the probe motion over the surface makes even a standard
AFM a versatile tool for manipulation surfaces at the nanoscale. There are a range of
techniques that have been used to modify surfaces, notably including local oxidation
[244], scratching [245] and dip-pen nanolithography [246].
