Microengineered Actuators: A Review

In the past decade, numerous microengineered mechanical devices have been fabricated successfully by exploiting and adapting the well-established integrated-circuit technology. Advancements in this field are motivated by potential applications in batch-fabricated integrated sensors and silicon-based microactuators. These devices promise new capabilities, as well as improved performance-to-cost ratio over conventional hybrid-manufactured devices. Micromachined transducers that can be fabricated compatibly with an integrated circuit process are the building blocks for integrated microsystems with added functionality, such as closed-loop control and signal conditioning. Furthermore, miniaturized transducers are powerful tools for research in the micron-sized domain in the physical, chemical and biomedical fields. This paper reviews the development of microengineered actuators (microactuators) based on crystalline silicon and polycrystalline silicon (polysilicon) as the structural materials. Several microactuator examples are first described. Various actuation methods adapted for micro-sized mechanical devices and fabrication techniques are evaluated. Finally, the direction for future research in light of the present challenges and potential applications of microactuators are considered.