THE CASE FOR MAGNETICALLY DRIVEN MICROACTUATORS

There has been a growing interest in microactuation, which we define as the ability to achieve motions with micron-level precision, and in microfabricated actuators, which we define as actuators which are themselves micron scale in size. Recent articles on microfabricated actuators have suggested that electrostatic approaches are more favorable than magnetic approaches. This article revisits these issues from the perspective of microactuation with application to microfabricated actuators. We show that magnetically generated forces can be made much larger than electrostatic forces even for 1-mu-m air gaps, that efficiency arguments are moot unless microfabricated actuators shrink further in size (in which case heat dissipation is a problem), and that the benefits of integration of electronics with a microactuator are questionable. We also show, by direct comparison of a magnetic and an electrostatic microfabricated actuator, that magnetic approaches which are wholly compatible with microelectronics fabrication can produce forces comparable to those from electrostatic approaches. From these arguments we conclude that the case for magnetic microactuation and magnetically driven microfabricated actuators is compelling, and that the advantages of microfabrication of actuators are not clear.