Modeling, microfabrication and experiments of a free–free cantilever bistable micro mechanism supported with a diamond configuration

Abstract

Bistable micro mechanisms are gaining great attention in MEMS applications. This paper presents the mechanical modeling and experimental characterization of a bistable torsion/cantilever micro latching mechanism for performing low power bistable relay applications. The bistable micro mechanism consists of two cantilevers which form symmetrical rocker levers. The free-free cantilever is suspended by a diamond skeleton which in turn is attached to a torsion cantilever. A permanent magnet is placed beside for holding the closed state with a permalloy soft magnetic circuit. The special diamond support is designed to enhance the stiffness of the overhang beams. In order to deduce the spring stiffness of system, a mechanical modeling of the leveraged torsion/cantilever system was performed by Castigliano's theorem. Meanwhile, the magnetostatic latching force was also deduced by the Maxwell electromagnetism theory. Then the device has been prepared by a laminated copper sacrificial layer process. This process can facilitate the fabrication complexities of traditional magnetic device with coil structures. Finally, mechanical performance was characterized by an atomic force microscopy, combined with finite element simulation using ANSYS TM package and analysis model as well. Two stable states of the micro mechanism were hold successfully with no power consumption by interferoscope profilometry of WYKO optical profiling system.

Torsion/cantilever-based MEMS bistable mechanisms with different support configurations: structure design and comparison

“…Assuming that the ESC of the ring-shaped MEMS BM system is also named as k S , then the stiffness coefficient of the ring-shaped MEMS BM (type 2) can be obtained as Assuming that the ESC of the diamond-shaped MEMS BM system is named as k S as well, then the stiffness coefficient of the diamond-shaped MEMS BM (type 3) can be expressed as [28]…”