A bistable shape memory microswitch with high energy density

作者：Barth J^*; Krevet B; Kohl M

来源：Smart Materials and Structures, 2010, 19(9): 094004.

DOI：10.1088/0964-1726/19/9/094004

A novel concept and various layouts of a bistable microswitch are presented, that combine an antagonistic shape memory alloy (SMA) actuation mechanism with two end positions, and magnetic components to maintain the end positions in the power-off state. The antagonistic SMA actuation mechanism consists of two mechanically coupled freely suspended TiNi microbridges of 20 mu m thickness that are pre-strained with respect to each other. The electro-thermo-mechanical response of the coupled microbridges is investigated for various degrees of pre-strain to determine the maximum actuation stroke, minimum required magnetic retention force and maximum switching force. Different layout variants consisting of hard-and soft-magnetic microstructures are compared and evaluated for magnetic retention. The optimization of the ferromagnetic attraction force of a specific layout is shown by finite element simulations. First demonstrator microswitches with outer dimensions of about 7 x 7 x 4 mm(3) are presented that show large work outputs featuring strokes and contact forces up to 84 mu m and 30 mN, respectively.

• 出版日期2010-9