Monolithic magnetic circuit for MEMS magnetic device

This paper proposes monolithic magnetic circuits for a micro-electro-mechanical system (MEMS) magnetic device. The problem with existing miniature magnetic devices is the fabrication of the miniature magnetic circuit, such as a winding wire. The proposed magnetic circuit has a miniature three-dimensional coil structure and a magnetic core within the monolithic structure. Multilayer ceramic technology that is used for miniature electronic elements is applied during the fabrication process. In this paper, various differently shaped single-coil or multi-coil-type magnetic circuits are described. Moreover, the magnetic flux of the circuits is analyzed and the circuit is applied to miniature magnetic devices. To produce the miniature mechanical components, the MEMS process is used. The fabricated single-coil-type circuit is applied to a MEMS magnetic motor. The developed MEMS magnetic motor has three multilayered circuits and is built within the MEMS structural component. The diameter and height of the motor are 4.22 and 6.04 mm, respectively. The multi-coil-type circuits are applied to a MEMS turbine generator. Both single-phase and three-phase generators are fabricated. The single-phase generator is combined with a multilayered step-wise shape circuit, in which the magnetic material is arranged around the magnet. The three-phase generator is combined with a separated type and has an air gap between each coil pattern. These two devices demonstrate rotational motion and power generation, respectively. The rotational speed of the MEMS motor is 1080 rpm. The output power of the single-phase and three-phase generators is 1.74 and 1.41 µVA, respectively.