Page 280 - Mechanics of Microelectromechanical Systems

5. Static response of MEMS 267
Solution:
As previously shown, the conditions for stable static equilibrium are:

The electrostatic force and the spring force are given in Eqs. (5.2) and
(5.3), respectively. The value of the pull-in displacement is also given in
the second Eq. (5.7). By combining these equations with the relationship
between and it is found that the voltage is U = 86.6 V.

2.2 Flexure-Spring Microdevices

Flexure-spring microdevices are used as acceleration sensors in
automotive control systems of airbags, chassis or navigation monitoring. The
simplest microaccelerometer consists of a flexure hinge and a tip mass, as
pictured in Fig. 5.4 (a).

Figure 5.4 Flexure-hinge microaccelerometer: (a) side view with schematic configuration;
(b) detail with displaced proof-mass