Development of electromagnetic induction type MEMS air turbine generator with ball bearing

This paper suggests the MEMS air turbine that used for the MEMS electromagnetic induction type generator. In the MEMS air turbine that employed the fluid dynamic bearing system, the gap between the magnet and the magnetic circuit and the eccentric motion of the rotor are problem in the high efficiency and the high output power. The developed MEMS air turbine has miniature silicon structure and the miniature bearing structure. The bearing structure is extended to suppress the eccentric motion and to close the gap between the magnet and the magnetic circuit. The dimension error of the fabricated MEMS air turbine components is less than ± 6 micro meter. Therefore, the microstructure with high-accuracy and high-aspect-ratio can be fabricated by the MEMS process. By forming the guide structure, the assembly error is less than ± 5 micro meter. The combined MEMS air turbine with the ball bearing is achieved, and the dimensions are 4.36 mm, 4.25 mm, and 3.60mm, respectively. Moreover, it is possible to close the distance of the gap by introducing the bearing structure. In the rotational experiment, the rotational motion of the rotor is achieved when the magnetic force applying from the outside of the fabricated turbine. Accordingly, it is possible to realize the rotational structure that is combined with the MEMS silicon components and the ball bearing. In the future work, in order to achieve the rotational motion by the air pressure, the rotational structure will be optimization about the reducing weight of the rotor and the air passage.