Page 210 - Mechanics of Microelectromechanical Systems

4. Microtransduction: actuation and sensing 197
mating counterpart‚ the attraction forces about the y-direction cancel out‚ and
therefore the only motion will be along the x-axis‚ where the attraction force
is unbalanced. This principle can be extended to the three-dimensional
space‚ as another direction can be denied mobility‚ by using symmetry about
the corresponding out-of-the-plane z-axis.

Figure 4.18 Using symmetry to enable motion about a given direction while blocking
motion about a different direction

Figure 4.19 Transverse (or parallel-plate‚ 1) versus longitudinal (or comb-finger‚ 2) motions
in an interdigitated microdevice