Biomedical Engineering Reference
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(a)
(b)
FIGURE 2.1
(
a) Scanning electron micrograph of a rectangular silicon cantilever.
(
b) A
closer view of the tip reveals its pyramidal shape obtained by the anisotropic etching of silicon.
(Images courtesy of Michael R ohrig, Karlsruhe Institute of Technology.)
and Marti, 2005)
4
√
3
596861
2
π
ρ
Si
l
2
f
0
t
=
(2.4)
0
.
E
Si
10
−
4
s/m
≈
7
.
23
×
2330 kg/m
3
.
The formulas presented above are only valid for rectangular cantilevers, but equa-
tions for V-shaped cantilevers were given by Neumeister and Ducker (1994) and
Sader (1995). Since the calibration of the cantilever is a key issue in every AFM
experiment, several researchers developed many other methods to calibrate the forces
measured with an AFM (Schwarz et al., 1996; Varenberg et al., 2003; Bilas et al.,
with the density of silicon ρ
Si
=
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