The name is absent

Figure 1.7: AFM image of an IgM antibody (image is approximately 20 nm x 20 nm in
size). Image taken from Reference [13].

In addition to topography, AFM is also able to obtain qualitative information about the
nature of the sample being imaged. For example, recent work has shown that AFM
imaging can be used to differentiate between healthy and cancerous cells [14, 15].

As mentioned above, the AFM is able to measure force versus distance curves. These
“force curves” are able to provide information about the properties of the tip, the sample,
and the medium in between. Material properties such as elasticity, adhesion and surface
charge density can be characterized using force curves. Thus, AFM force curve analysis
has found applications in many fields including biology.

In an AFM force curve measurement the, tip-cantilever assembly is held stationary in the
horizontal direction and is moved up and down vertically relative to the sample. The
vertical position of the tip and deflection of the cantilever are recorded and converted to
force-versus-distance curves (see Figure 1.8). The stochastic nature of force curves
requires that many individual force curves be taken in order to obtain accurate physical
information.

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