A bi-stable mechanism actuated by patterned permanent magnet and Cu-Ni integrated micro-coil

Abstract

Abstract This paper presents a bi-stable mechanism, which mainly consists of a suspended mass, a spacer and a bottom plate. Electromagnetic actuation is used for switching between two states (i.e. ‘On/Off’ state). The actuation is achieved via permanent magnet (PM) on the suspended mass and micro-coils embedded in the bottom plate. Different from spiral coil and central core in conventional design, micro-coils in this paper integrate Cu and Ni together as a whole, acting as both coil and ferromagnetic core. This integration simplifies the fabrication into one-mask process. Furthermore, chessboard patterned PM is utilized with Cu-Ni integrated micro-coils to generate enhanced force density. The bi-stable mechanism is designed, fabricated and experimentally characterized. Total size of this mechanism is 16 × 14 × 2 mm3. No power is needed for holding either of the state. Switching processes (both ‘On’ to ‘Off’ and ‘Off’ to ‘On’) can be realized with external acceleration of 24 G (gravity) and 37 G, respectively. Furthermore, resetting (i.e. ‘On’ to ‘Off’) can also be accomplished with 1.5 A current input.