High precision microactuators have become key elements for many applications of MEMS, for example for positioning
and handling systems as well as for microfluidic devices. Electromagnetic microactuators exhibit considerable benefits
such as high forces, large deflections, low input impedances and thus, the involvement of only low voltages. Most of the
magnetic microactuators developed so far are based on the variable reluctance principle and use soft magnetic materials.
Since the driving force of such actuators is proportional to their volume, they require structures with rather great heights
and aspect ratios. Therefore, the development of new photo resists, which allow UV exposure of thick layers of resist,
has been essential for the advancement of variable reluctance microactuators. On the other hand, hard magnetic
materials have the potential for larger forces and larger deflections. Accordingly, polymer magnets, in which micro
particles of hard magnetic material are suspended in a polymer matrix, have been used to fabricate permanent magnet
microactuators. In this paper we give an overview of sophisticated electromagnetic microactuators which have been
developed in our laboratory in the framework of the Collaborative Research Center “Design and Manufacturing of
Active Microsystems”. In particular, concept, fabrication and test of variable reluctance micro stepper motors, of
permanent magnet synchronous micromotors and of microactuators based on the Lorentz force principle will be
described. Special emphasis will be given to applications in lab-on-chip systems.