Thesis-PDF - IAP/TU Wien

it scans across the surface can be recorded and used for deriving information on
surface topography and other surface properties. The forces exerted on the sample
during the scanning process can be limited in the feedback circuit that regulates
the z-height of the cantilever tip.
There are basically two modes of operation in AFM, the static mode and the
dynamic mode. (This classification follows [38].)
Figure 3.2: AFM Contact Mode images of endothelial cells. 65 × 65 µm 2 ,
left: height trace, right: first derivative of height trace. A thin layer of
endothelial cells builds the interior surface of blood vessels. They are present
in the entire circulatory system, from the heart to the smallest capillary and
reduce friction between the circulating blood and the vessel walls. The height
of endothelial cells typically measures up to 4 µm. Image adapted from [39].
Figure 3.3: AFM Intermittent Contact Mode images of endothelial cells.
65×65µm 2 , left: height trace, right: first derivative of height trace. Because
of the reduced contact forces, the imaged cell membranes are pressed less
against the cytoskeleton than in Contact Mode. ([39])
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