ABSTRACT
The subject of mechanical actuation in microengineered structures is an expanding area of study. Amongst the easiest actuation mechanisms to understand are capacitive, electromagnetic and thermal. Capacitive techniques are material independent, but require very small separations to be effective. Electromagnetic actuation is similarly material independent, but does need an external magnetic field. Typical thermal actuators are either bimetallic in form, or incorporate diffused resistors to dissipate the heat.
A lot of recent research has been generated in using material dependent properties such as piezoelectricity, the shape memory effect, electrostriction and magnetostriction. These are more developed in large structures, but on the micro scale the reproduction of material dependent properties has been a major problem limiting the application of techniques that promise a large actuation force and simple fabrication procedures.
