micro-electro-mechanical systems abbr., MEMS otherwise microelectromechanical systems; micromachines (Japan); micro systems — MST (Europe) (rus. микроэлектромеханические системы abbr., МЭМС) — technologies and devices made up of microelectronic and micromechanical components.

Description

Microelectromechanical systems (MEMS) are integrated devices assembled on a semiconductor (usually silicon) substrate that contain mechanical elements, sensors, actuators and electronic components. Micromechanical elements (system components) are typically between 1 to 100 microns in size, and crystals of MEMS integrated circuits range in size from 20 micrometres to one millimetre. Microelectromechanical systems are manufactured using semiconductor manufacturing technologies, such as CMOS *), BiCMOS †), etc., which are based on standard process operations of thin film deposition, lithographic patterning, etching, etc. Compatible micromachining processes are used in the manufacture of mechanical and electromechanical components of MEMS. These processes allow the selective etching of elements of a silicon substrate or the addition of new structural layers.

Being a combination of semiconductor electronics and mechanical elements fabricated with micromachining methods, MEMS enable development of a fully functional laboratory on a chip. The computing power of microprocessors is augmented in solutions of this kind by the capability for perceiving the environment using integrated microsensors and manipulation of the environment with integrated microactuators. The microelectronic integrated circuit serves as the “brain” of the system, while MEMS becomes the system’s “eyes” and “hands”, allowing the system to sense and control various parameters of the environment. The system’s microsensors can collect different environmental data by measuring mechanical, temperature, biological, chemical, optical and magnetic parameters; microprocessors, in turn, process the obtained data and engage the decision-making algorithm to respond to these parameters using microactuators that control movement, positioning, stabilisation, filtering and other processes. The production of MEMS devices involves the application of multiple process methods derived from microelectronics, which enables, at a relatively low cost, the implementation, on a small semiconductor chip, of systems characterised by their unprecedented complexity, functional capabilities and reliability.

Due to the increasingly small sizes of components manufactured by means of MEMS technologies, they are used today for the fabrication of a wide range of devices. Examples of the most common devices are listed below.

1. Accelerometres – devices to gauge acceleration that are used in airbag sensors in the automotive industry.

2. Digital Micromirror Device (DMD) – an optical modulator comprised of a micromirror array. DMD creates an image by successively turning its micromirrors ON and OFF and reflecting the incident light onto the optical projection system (ON) or absorber (OFF).

3. Microcapillary devices – silicon chips with microchannels for the precise delivery of specific quantities of substances. These devices may find application in inkjet printers for spraying ink on paper or in an integrated medical microdevice consisting of a glucose sensor and an insulin dispenser.


*) CMOS (complimentary metal-oxide-semiconductor transistor) – complimentary logic based on metal-oxide-=semiconductor transistors.

†) BiCMOS (bipolar complimentary MOS-transistor) – an integrated circuit manufacturing technology that integrates bipolar and CMOS transistors on one chip.

Illustrations

MEMS-based devices top to bottom and left to right: а — flexible attachment of microgears; b —
MEMS-based devices top to bottom and left to right: а — flexible attachment of microgears; b — microdynamometer that allows measuring longitudinal and axial forces and evaluating microfriction. Moving pivot and arc scale are marked by an error; c — microactuator; d — driving gear; e— optical switch: silicon tooth gear may be mechanically set in four different positions that correspond to signals (0, 0), (1, 0), (0, 1) and (1, 1) (two positions are marked by arrows); information is retrieved by a fixed focused laser beam; f — microtransmission device converting rotary motion into propulsion; g — moving silicon micromirror (shown by an error) that may change its tilt angle due to propulsion of piston driven by the transmission device; h — light shutter; i — three-cylinder steam engine: water in each cylinder is heated by electric power, steam pushes the piston out, and when the liquid cools down, the piston is drawn back into the cylinder by the capillary forces. Adapted based on microphotographs from Sandia National Laboratories website, www.mems.sandia.gov [3].

Authors

  • Razumovsky Alexey S.
  • Bratishev Alexey V.

Sources

  1. MEMS and Nanotechnology Exchange. —www.mems-exchange.org (reference date: 12.12.2011).
  2. Sandia National Laboratories. —www.sandia.gov (reference date: 12.12.2011).
  3. Nanotechnologies. ABC for everyone (in Russian)// Ed. by Tret'jakov Ju. D. — Moscow: Fizmatlit, 2008. — 368 p.

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