Abstract
An attempt has been made to summarize some of the important developments in the emerging technology of microelectromechanical systems (MEMS) from the mechanical engineering perspective. In the micro domain, design and fabrication issues are very much different from those of the macro world. The reason for this is twofold. First, the limitations of the micromachining techniques give way to new exigencies that are nonexistent in the macromachinery. One such difficulty is the virtual loss of the third dimension, since most of the microstructures are fabricated by integrated circuit based micromachining techniques that are predominantly planar. Second, the batch-produced micro structures that require no further assembly, offer significant economical advantage over their macro counterparts. Furthermore, electronic circuits and sensors can be integrated with micromechanical structures. In order to best utilize these features, it becomes necessary to establish new concepts for the design of MEMS. A set of key joints and mechanisms using which majority of the mechanical devices can be built, is identified. It is surmised that such an effort will be advantageous in designing micromechanisms as they form the basis for what we call fabrication building blocks (joints) and synthetic building blocks (mechanisms). The paper also reviews some of the fabrication techniques and the micromechanical devices that have already been made, and makes suggestions regarding the fabrication of a few generic mechanisms that can be made using these techniques. In particular, it discusses the fabrication of a motor-driven four-bar linkage using the “boron-doped bulk-silicon dissolved-wafer process” developed at The University of Michigan’s Center for Integrated Sensors and Circuits.
