MICROMECHANISMS

Micromechanics deals with micromechanisms which fall into two broad ca tegories: sensors and actuators. Since sensors measure some property o f their environment, internal sensor power dissipation should be minim ized and sensor sensitivity must be maximized. In force sensing, power dissipation has been reduced by ten decades in twenty years. Sensitiv ity has been increased by twelve decades and is now being limited by t hermal noise problems. Practical force sensing via mechanically resona nt devices, which can be powered by unmodulated light and sensed by op tical reflections, has been demonstrated and has major implications on future sensing systems. Actuators are devices which do work on their environment. The tool to produce microactuators is still a major probl em. X-ray-assisted processing with very large structural heights satis fies most of the tool requirements for microactuators. It has been use d, along with assembly, to produce magnetic actuators, such as rotatio nal motors, with 120 mu m rotors and rotational speeds of up to 150 00 0 rpm. A generic linear electrostatic actuator with large travel and l arge output force per unit chip area addresses practical markets for t his evolving technology.