There is no universal agreement around the world on the correct terminology for describing this new technology. As a result, the terms MEMS, microtechnology, micromachines, and Micro Systems Technology (MST), have gained currency around the globe for its description, where each term seems to characterize one or more facets of its character.
MEMS devices have the following attributes:
MEMS (Micro Electro Mechanical Systems) has been developing since the 1980s, and is typically an “embedded” technology rather than a product in its own right.
While still a relatively new technology, MEMS brings together many diverse techniques to fabricate electronics, miniaturized sensors, actuators, as well as systems made up from these elements. It is primarily focussed on the miniaturization of mechanical systems and the exploitation of the unique attributes of silicon in these miniature systems.
MEMS is the convergence of a multitude of technologies and disciplines – physics, chemistry, engineering, biotechnology, medicine, nanotechnology, materials science, microelectronics, lithography and information technology – deployed in structures and devices with features in the micron domain. A micron is 1 millionth of a meter or 1 thousandth of a millimeter. For comparison, a human hair is 100 microns in diameter and a human body cell is typically several microns across.
MEMS technology is not merely concerned with making things smaller. Its primary significance is that it offers an alternative manufacturing paradigm and to date has made great contributions to the areas of computer peripherals, sensors, automobiles, biotechnology, micro actuators and micro sensors.
MEMS devices typically have both electrical and mechanical functionality, and are manufactured using the batch process techniques originally developed for the manufacture of silicon integrated circuits (ICs) for the semiconductor industry. The manufacturing techniques include:
MEMS has evolved into a highly complex field involving advanced processes of bulk and surface micromachining, including wet and dry etching techniques. There are also some unique machining processes such as the LIGA process which uses synchrotron radiation for the production of high-aspect ratio precision microstructures, and deep reactive ion etching (DRIE) which is also a silicon etching process for high aspect ratio structures. The use of silicon in MEMS devices allows some system functions to more closely approach ideal operation than if implemented using microelectronics.
Small scale technologies cover the size range from the nano scale (1 millionth of a millimeter) through to the micro scale (1 thousandth of a millimeter) and allow us to produce products and control processes at extremely small scales. Over the next two decades, such small scale technologies will have a profound impact on industrial products and processes as well as on individuals and society as a whole.
The dominant properties of matter change at small dimensional scales so small scale technologies have the potential to provide new solutions to problems through new approaches to manufacturing and fabrication. These changes will alter current attitudes to what is technically achievable in manufacturing and have the potential to radically transform many industries including those of health care, transport, packaging, computers, sports, food processing, environmental monitoring and scientific and medical equipment manufacture. For example, new handheld devices have been and are being developed which can be used in a doctor’s surgery to give a full blood analysis in under 90 seconds from a single drop of blood.
Existing products include inkjet printer heads, accelerometers for airbag deployment, gyroscopes, sensors, displays, optical switches, computer disk read/write heads, bio-chips, the Bionic Ear, heart pacemakers, and micro motors. Emerging products include micro displays, fingerprint identification sensors, lab-on-a-chip and needle-less drug delivery systems. These small scale technologies are inherently disruptive in that they will challenge and displace not only existing products, but also herald an era of new manufacturing techniques requiring clean rooms, sophisticated processing equipment and a highly skilled workforce.
MEMS was named one of the Top 25 Innovations in the past quarter century by CNN in an article available online.