44
G. K. Ananthasuresh
Fig. 19 A multi-concentric ring gyroscope that combines the features of polychromator design in
Fig. 10 and the compactness of the very flexible spring of Fig. 16a. It also embodies the principle
of the ring gyroscope shown in Fig. 18 in terms of placing the electrodes in two groups, but with
more concentric electrodes for resonance actuation and capacitive sensing
These two limitations were overcome to a large extent with a clever and economical
design [7], as explained next.
Figure 19a shows concentric rings where adjacent ones are connected to each
other in a staggered manner. Compare this with the designs in Figs. 10 and 16a.
The design in Fig. 19a inherits the features of these two designs. Consequently,
the stiffness of the concentric ring structure is made low, and the distortion at the
midpoints of the arc beams is reduced (see Fig. 19b). In Fig. 19c, d, the electrodes
for actuation and sensing are shown in top view and isometric views. This design
of the micromachined gyroscope achieved resolution better than 0.01 °/h [29]. It is
a great example of economical use of material with minimum etching of material
resulting in superior performance.
8 Ubiquity of Electrothermal Microactuators
Electrostatic actuators, comb drive actuator being the prime example, are widely
used in many MEMS sensors. But the force they generate is rather small—barely
moving themselves and only occasionally moving something else. Electromagnetbased and electrothermal actuators, on the other hand, can generate much larger force.
G. K. Ananthasuresh
Fig. 19 A multi-concentric ring gyroscope that combines the features of polychromator design in
Fig. 10 and the compactness of the very flexible spring of Fig. 16a. It also embodies the principle
of the ring gyroscope shown in Fig. 18 in terms of placing the electrodes in two groups, but with
more concentric electrodes for resonance actuation and capacitive sensing
These two limitations were overcome to a large extent with a clever and economical
design [7], as explained next.
Figure 19a shows concentric rings where adjacent ones are connected to each
other in a staggered manner. Compare this with the designs in Figs. 10 and 16a.
The design in Fig. 19a inherits the features of these two designs. Consequently,
the stiffness of the concentric ring structure is made low, and the distortion at the
midpoints of the arc beams is reduced (see Fig. 19b). In Fig. 19c, d, the electrodes
for actuation and sensing are shown in top view and isometric views. This design
of the micromachined gyroscope achieved resolution better than 0.01 °/h [29]. It is
a great example of economical use of material with minimum etching of material
resulting in superior performance.
8 Ubiquity of Electrothermal Microactuators
Electrostatic actuators, comb drive actuator being the prime example, are widely
used in many MEMS sensors. But the force they generate is rather small—barely
moving themselves and only occasionally moving something else. Electromagnetbased and electrothermal actuators, on the other hand, can generate much larger force.