A novel bistable thermally actuated snap-through actuator for out-of-plane deflection

In this paper , the importance of boundary conditions for two- way bistable thermal snapping action is analysed by Ansys simulations. Several designs are developed and modified into a novel bistable actuator for out of plane deflection. It consists of 4 long epi-silicon single layered legs , a 1200um x 40um x 3um microbeam and 4 spring-supports in which both are polysilicon/oxide/episilicon layered. Buckling of the released structure is achieved by the compressive residual stress remaining in the oxide layer as a result of the processing. The structure switches between two stable equilibrium states by heating the legs and then heating one of the polysilicon layers to produce the thermal moment needed for snapping to occur, hence achieving two-way bistable operation.

[1]  M.C. Wu,et al.  MEMS with thin-film aerogel , 2001, Technical Digest. MEMS 2001. 14th IEEE International Conference on Micro Electro Mechanical Systems (Cat. No.01CH37090).

[2]  Stefan Schulz,et al.  Thermal conductivity of ultra low- k dielectrics , 2003 .

[3]  K. Sarabandi,et al.  Electromechanical considerations in developing low-voltage RF MEMS switches , 2003 .

[4]  J. Lang,et al.  A high-current electrothermal bistable MEMS relay , 2003, The Sixteenth Annual International Conference on Micro Electro Mechanical Systems, 2003. MEMS-03 Kyoto. IEEE.

[6]  M. Saif.  On a tunable bistable MEMS-theory and experiment , 2000, Journal of Microelectromechanical Systems.