Micro-rotational electromagnetic generator for high speed applications

This paper presents the development of a micro-rotational electromagnetic generator for high speed applications. The generator followed an axial flux permanent magnet design. It was constructed with a rotor composed of multiple permanent magnet poles and a stator made of stacking micro-fabricated planar coils (25 mm in diameter and 2 mm thick, not considering the casing). The rotor is composed of commercially available NdFeB permanent magnets (6 × 2 × 1 mm) while the rotor is made of 10 individual copper-clad polyimide layers (18 μm thick copper, 25 μm thick polyimide). The planar micro-coils were manufactured by photolithography with 100 μm line width copper tracks. The rotor was assembled by placing the permanent magnets in a CNC-machined slotted disk. The generator was capable of producing 3.2V and 5.8 mW of power at a rotational speed of 4,000 rpm.