A bistable snapping microactuator and its mechanical analysis
- Univ. of California, Los Angeles, CA (United States)
A bistable, micromechanical switching device and its buckling stability, heat transfer, and dynamics analyses are summarized. A SEM picture of the device. The buckling element of the microactuator is a U-shaped cantilever ({open_quotes}buckled cantilever{close_quotes} in the picture) consisting of two 0.8 micron-thick polysilicon layers with 0.5 micron-thick oxide insulator sandwiched between them. The 82 micron-long cantilever is buckled by the {open_quotes}tension band{close_quotes} made of 0.5 micron-thick silicon nitride. The snapping action of the microactuator to the down-state (or up-state) is achieved by heating the upper (or lower) polysilicon layer of the buckling cantilever with electric current. Analysis of a snapping action between two buckled states is described. It provides a design framework as well as operation guidelines for the actuator. The buckling stability criterion and the deflection of the buckled cantilever are discussed by using a pinned-pinned, double-layer model. Perfect thermal insulation is assumed between the two independently heated layers. The full analysis and testing have shown that the buckling does not occur if the mean expansion of the buckling cantilever is not compensated by the elongation of the tension-band anchor. Because of the flatness of the cantilever, a one-dimensional heat transfer model across the three layers of the cantilever turns out valid. The numerical analysis shows that, during heating, the temperature difference between the two polysilicon layers reaches a steady value (estimated as 33 K) in less than 1{mu}s. However, cooling is much slower due to the low heat transfer coefficient of air; it takes 0.5 ms to dissipate 90% of the heat gained by the heating.
- OSTI ID:
- 175278
- Report Number(s):
- CONF-950686-; TRN: 95:006111-0233
- Resource Relation:
- Conference: Joint applied mechanics and materials summer meeting, Los Angeles, CA (United States), 28-30 Jun 1995; Other Information: PBD: 1995; Related Information: Is Part Of AMD - MD `95: Summer conference; PB: 520 p.
- Country of Publication:
- United States
- Language:
- English
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