Microelectromechanical systems, or MEMS, constitute a group of microdevices that are just beginning to affect many areas of science and technology. In diverse fields including the automotive industry, aeronautics, cellular communications, chemistry, acoustics, and display technologies and other photonic systems, these highly functional devices are making a big name for themselves, despite their diminutive size.

The rapid expansion of microelectromechanical systems (MEMS) into new application areas is due in large part to the development of surface-micromachining techniques that allow the fabrication of a wide variety of MEMS devices with structural components that can execute motion in at least one direction.

While microelectromechanical systems (MEMS) technology has made a substantial impact over the past decade at the device or component level, it has yet to realize the “S” in its acronym, as complex microsystems consisting of sensors and actuators integrated with sense, control, and signal-processing electronics are still beyond the current state of the art. There are several incentives to co-fabricate MEMS devices and electronics on a single silicon chip, which apply to applications such as inertial sensors.

Microelectromechanical systems (MEMS) devices are being manufactured in the hundreds of millions and are widely deployed for pressure sensor, accelerometer, display, and printing applications. This suggests customer confidence in the longterm reliability of MEMS (also known as microsystems or micromachines) under diverse stringent conditions.

The field of microelectromechanical systems (MEMS) involves the interaction of the physical environment with electrical signals through the use of microbatchfabricated devices. MEMS is a growing technology, and commercial MEMS products are becoming commonplace.

Because of large surface-to-volume ratios and low restoring forces, unwanted adhesion and friction can dominate the performance of microelectromechanical systems (MEMS) devices. To guarantee the function and reliability of MEMS devices, tribologists must understand the origins of adhesion, friction, and wear over a broad range of length scales from the macroscopic to the molecular. In this article, we present an overview of challenges, successes, and initial steps toward a fundamental understanding.

Testing microelectromechanical systems (MEMS) includes testing a variety of electrical and mechanical signals. While powerful tools are available to test the electrical behavior of microfabricated systems, relatively few tools are available to measure micromechanical behavior.

Many microelectromechanical systems (MEMS) use the changing capacitance of movable parallel plates to drive and sense motion. An increase in this capacitance improves the performance of these micromechanical structures by means of increased electromechanical coupling for lower driving voltages and increased sensitivity of the micromechanical motion.

The designer of microelectromechanical systems (MEMS) can increase MEMS performance either by improved mechanical design or by the selection of a MEMS material with improved mechanical performance. In the quest to identify highperformance MEMS materials, diamond and amorphous carbon have recently emerged as a promising class of materials.

Microelectromechanical systems (MEMS), microsystems technology (MST), and micromachines are roughly synonymous terms applied in the United States, Europe, and Japan, respectively, for manufacturing technologies that are enabling miniaturization and the development of useful products.

The infusion of advanced technology into defense systems is accelerating, by necessity, to keep pace with the exponential growth in information accessibility. Critical to national security and global stability, military forces must sustain their technological edge over potential adversaries. It is obvious that such an advantage cannot be maintained by sole reliance on protecting access to high-tech information.

The U.S. Air Force Research Laboratory's (AFRL) aggressive pursuit of reducing the size and weight of satellite systems for advanced space missions is providing a vital thrust to the development of “systemson-a-chip.” Adaptive optics technologies offer tremendous potential in reducing the weight and cost of space-based optical systems.

The possibility of an all-digital (sourceto-eye) projection display was realized in 1987 with the invention of the Digital Micromirror Device™ projection display chip at Texas Instruments (TI). The DMD™ chip is a microelectromechanical systems (MEMS) array of fast digital micromirrors, monolithically integrated onto and controlled by an underlying silicon memory chip. Digital Light Processing™ projection displays are based on the DMD chip. DLP™ projection displays present bright, seamless images to the eye that have high image fidelity, and stability.

As demonstrated in this issue, the emerging field of microelectromechanical systems (MEMS) is beginning to impact almost every area of science and technology. MEMS have the potential to revolutionize light-wave systems. Microdevices such as optical switches, variable attenuators, active equalizers, add/drop multiplexers (ADMs), optical cross-connects (OXCs), gain tilt equalizers, data transmitters, and many others are beginning to find ubiquitous application in advanced light-wave systems.

The increasing demand for wireless communication applications, such as cellular and cordless telephones, wireless data networks, and global positioning systems, motivates a growing interest in building miniature radio transceivers that can support multistandard capabilities. Such transceivers will greatly enhance the convenience and accessibility of various wireless services.

Over the past decade, there has been an explosive growth in efforts directed at developing and utilizing an array of novel microsystems in important applications in chemistry and biology. In parallel, the commercial potential of these applications has fueled the creation of hundreds of new companies and the expansion of research and development efforts at established commercial organizations. In this article, we outline the spectrum of applications of these systems and highlight some of the materials and fabrication challenges that they present.

LIGA, an acronym for the German words for lithography, electroplating, and molding, is a technique used to produce micro-electromechanical systems (MEMS) made from metals, ceramics, or plastics. The LIGA process utilizes x-ray synchrotron radiation as a lithographic light source. Highly collimated, high-energy x-rays from the synchrotron impinge on a patterned mask in proximity to an x-ray-sensitive photoresist, typically poly(methyl methacrylate) (PMMA).