229Mechanical Nanosensors
How is a cantilever beam actuated for oscillations and how is its resonance fre-
quency measured?
1. In magnetomotive motion actuation, the Lorentz force generated upon
a current-carrying conductor in a static magnetic eld supplies the
actuation force. Here, an AC current is driven through the beam in
the presence of a strong magnetic eld.
2. In electrostatic (capacitive) motion actuation, a gate electrode is fabri-
cated in the vicinity of the beam and a voltage is applied between
the gate electrode and the device. The actuation force depends non-
linearly upon the excitation voltage and has components present at
higher harmonics. To obtain a large contribution at the drive fre-
quency, a voltage having a large