Page 285 - Mechanical design of microresonators _ modeling and applications

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Resonant Micromechanical Systems

284 Chapter Five
z
symmetry axes ω

F
x

(a) (b)
Figure 5.57 Model of double-ended tuning fork: (a) quarter structure; (b) fixed-guided
beam model of quarter structure.

12.5
0.1
f×10 8
2.5
0.08
c t
cw
0.1 0.08
Figure 5.58 Plot of the f function, Eq. (5.152).

5.7 Resonant Accelerometers

There are two basic procedures to sense external acceleration by using
resonant sensors. Both procedures are based on detecting shifts in a
resonator’s natural frequency as produced by changes in stiffness. The
change in stiffness can be determined by an additional bending due to
acceleration or to the action of an axial force, also produced by acceler-
ation.
When the acceleration produces an additional bending moment on a
microcantilever, for instance, which will displace the resonator’s tip by
a small quantity measured by the angle Į, as shown in Fig. 5.59, the

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