Micro-Electro-Mechanical System (MEMS) technology has been identified as one of the most promising technologies in the next century for its potential in making smaller, lighter and more functional electro-mechanical devices or machines at lower costs. MEMS is a new technology leveraging the enormous capital investment in the IC fabrication technology. MEMS devices are already emerging as products in both commercial and defense markets such as automotive, aerospace, medical, industrial process control, electronic instrumentation, office equipment, appliances, and telecommunications. Current products include: airbag crash sensors, pressure sensors and ink jet printer heads. The technology uses silicon microfabrication, together with other advanced precision machining technologies, as the main tool to realize various novel designs of micro machines and devices.
The impact of the technology have been seen or foreseen in many Hi-Tech industries, such as data-storage industry, information-communication industry, bio-engineering industry and automotive industry. Extensive R&D works in MEMS are now being undertaken in all the top universities in the world.
What identifies a MEMS?
MEMS (MicroElectroMechanical Systems) is a class of system that share the presence of micro-machined parts. Usually they are physically small, but they may be relatively large (e.g, a ink-jet printer cartridge). These systems have both electrical and mechanical components. MEMS originally used modified integrated circuit (computer chip) fabrication techniques and materials to create these very small mechanical devices. Today there are many more fabrication techniques and materials available.
Sensors and actuators are the two main categories of MEMS. Sensors are used to measure parameters of the environment while actuators modify this environment. Micro sensors are interesting because their small physical size allows them to be less intrusive. Micro actuators are useful when small and very precise displacement is needed.
Polysilicon Resonator Transducers are an example of a MEMS sensor using a stress controlled thin film polysilicon process, which is a modification of integrated circuit fabrication techniques. The sensor uses a mechanically free beam of polysilicon whose resonant frequency can be measured electronically. Environmental changes can be converted to a change in resonant frequency of the micro beam and can be sensed. It is interesting to note that the first MEMS device was a gold resonating MOS gate structure.
Using deep x-ray lithography and electro-deposition process we can also fabricate magnetic Micro Motors and precision Engineered Gears. MEMS can be used to create parts of systems where high tolerances are necessary. Gears bridge the gap between MEMS and traditionally machined precise components.
You may look at a more complete presentation introducing many of the different aspects of the MEMS technology. If you feel you would want to know more, go further and read the (not so) short introduction to MEMS, a free one chapter introduction to MEMS technology.
