MEMS to NEMS

In 1959, Richard Feynman proposed the possibility of ultraminiaturisation (size reductions by as much as a factor of 4000) of mechanical systems as well as miniaturising computers to levels involving the manipulation of atoms. While these ideas were undoubtedly prophetic, the technique envisaged, of three-dimensional machines iteratively making ever-smaller versions of themselves, is unlikely ever to be practical (a point acknowledged by Feynman himself, after revising the concept in 1983).

An important factor in the progress of miniaturisation technologies is the development of microelectromechanical systems (MEMS), also known as (micro)mechatronics. MEMS consist of integral micromechanical and microelectronic elements fabricated by established semiconductor processing techniques. Examples of miniature components which can be produced in this way include pressure and acceleration sensors, linear actuators, valves, grippers, tweezers, motors, gear trains, turbines, nozzles, and pumps.

MEMS are now regarded as a critical technology in fields such as the aerospace, automotive, biomedical, and communications industries. Commercial applications of MEMS include microfluidic manipulators for implantable drug dispensers, navigation gyros for aerospace use and magnetic and optical storage, switching devices and displays for information technology.

Nanoelectromechanical systems or NEMS is the next logical miniaturization step from MEMS, and is used to describe devices integrating electrical and mechanical functionality on the nanoscale. Often employing the 2010 Nobel physics prize winning material, graphene, together with the last century’s wonder material, carbon nanotubes, NEMS systems have found much application in atomic force microscopy (AFM).

Currently, the most significant technologies for the fabrication of three-dimensional MEMS microstructures are bulk micromachining, surface micromachining, LIGA (from the German "Lithographie, Galvanoformung, Abformung" - a process involving X-ray lithography, electroplating and plastic moulding),  electrical discharge machining (EDM), and substrate bonding. NEMS systems rely on two basic principles of fabrication: photo/electron beam lithography, and molecular self assembly.

All aspects of MEMS, NEMS and micromanufacturing technology are covered comprehensively in the Inspec Database. Papers can be found in Section A (Physics), Section B (Electrical and Electronics Abstracts), Section C (Computer and Control Abstracts) and Section E (Mechanical and Production Engineering). The most important classification sections are:

• A0710C Micromechanical and nanomechanical devices and systems
• A4283    Micro-optical devices and technology
• A4284    Nanophotonic devices and technology
• A8116    Methods of nanofabrication and processing
• B2550    Semiconductor device technology
• B2550    Nanometre-scale semiconductor fabrication technology
• B2575    MEMS and NEMS device technology
• B4145    Micro-optical devices and technology
• B4146    Nanophotonic devices and technology
• B7230    Sensing devices and transducers
• B8340    Small and special-purpose electric machines
• B8380M Microactuators
• C3240P  Microsensors
• C3260P  Microactuators
• E1520A  Machining
• E1520P  Nanofabrication
• E2160    Micromechanics
• E3644T  Nanotechnology industry
• E3644V Mechatronics industry

Inspec controlled indexing terms for MEMS and NEMS technology include:

• bioMEMS
• mechatronics
• micro-optomechanical devices
• microactuators
• microdisplays
• microfluidics
• micromachining
• micromanipulators
• micromechanical devices
• micromechanical resonators
• micromirrors
• micromotors
• micropumps
• microrobots
• microsensors
• microswitches
• microvalves
• nanobiotechnology
• nanocontacts
• nanoelectromechanical devices
• nanoelectronics
• nanofabrication
• nanofluidics
• nanolithography
• nanomagnetics
• nanomechanics
• nanopatterning
• nanophotonics
• nanopositioning
• nanosensors
• nanotechnology
• nanotube devices

Other relevant controlled index terms for some of the ideas discussed in this article are:

• accelerometers
• atomic force microscopy
• automotive electronics
• carbon nanotubes
• electrical discharge machining
• electron beam lithography
• electroplating
• graphene
• lab-on-a-chip
• micro-optics
• photolithography
• pressure sensors
• self-assembly
• semiconductor technology
• sputter etching
• wafer bonding
• X-ray lithography