Biomedical Engineering Reference
In-Depth Information
Fig. 7.28. Examples of commercial products with applications in AFM. Left: 4
m
4
m image
of a razor blade. Middle: image of clay-containing coating on paper, showing hexagonal kaolin
particles. Right: 35
m
35
m image of human hair.
Another motivation for companies that make commodity products to use the AFM is to
solve production problems. As an example, a company that makes photocopy machines
was having problems with the machines breaking because the particles used in the
reproduction process were not working correctly. By using an AFM the company was
able to find that the particles purchased from another company did not meet their
specifications. Before it was solved the problem was costing the company approximately
1 million dollars per month.
In addition, AFM analysis can be used to support advertising claims, or to resolve
industrial disputes. As an example, a toothbrush manufacturer was claiming that their
product caused less damage to teeth than their competitors. The competitor challenged this
claim with a law suit. An AFM was then used to compare the wear on teeth from the two
companies' products. In fact, it was demonstrated that the claims were true.
Figure 7.28 shows a few examples of commercial samples scanned with an AFM. The
razor blade image is an example of using AFM to characterize defects caused by faulty
processes. Razor blades are sharpened to atomic dimensions in extremely high volumes.
The AFM was used to profile the sharpened surface and view imperfections at the very
edge of the blade. Mounting the razor blade in the AFM so that the scans could be made
without causing further damage was a substantial challenge.
Secondly, a paper coating is shown. The quality of paper coatings greatly affects their
performance, and many papers are complex composite materials, containing different
mineral particles, elastic binders, and fibres in the surface structure. For centuries paper
products have been made from nanoparticles. A common component which controls the
quality of the paper is clay. Often, the higher the clay content, the higher quality the paper.
An AFM can readily be used to visualize the clay nanoparticles in paper. The image in
Figure 7.28 shows an AFM image of Astr-Plus/Carbinal 95 coating. This 'engineered'
coating is comprised of kaolin in a narrow particle size distribution and an ultra-fine
ground calcium carbonate with a latex binder. AFM is a highly suitable tool for imaging
and quantitative analysis of paper coatings [724, 725].
The final example of a commercial sample for AFM is hair treatments. Hair care
products can cause substantial changes to the overall geometry of human hair. The
changes can affect the hair's optical and frictional properties which are very important
to consumers. AFM is the only method that is able to measure the three-dimensional
