Permanent magnet micromotors on silicon substrates

Different types of sliding, rolling, or rotating micromotors with rare-earth-based permanent magnet rotors are presented. The magnets move synchronously with rotating or traveling magnetic fields generated by 25- mu m-thick gold current lines on silicon substrates. The magnets are guided in channels or openings in the silicon itself or in additional glass layers. For magnets with a typical dimension of 1 mm, forces and torques of 150 mu N and 100 nNm could be achieved. Maximum velocities of 24 cm/s and a rotation frequency of 2000 r.p.m. have been measured. Magnetic clamping to the bottom confines the rotor to the system and allows a motor operation at any tilt angle. Noncontact magnetic transmission of forces to drive a ferromagnetic fluid has been demonstrated.>