ystems) Tiny mechanical devices that are built onto semiconductor chips and are measured in micrometers. In the research labs since the 1980s, MEMS devices began to materialize as commercial products in the mid-1990s. They are used to make pressure, temperature, chemical and vibration sensors, light reflectors and switches, as well as accelerometers for vehicle airbags, smartphones, tablets and games (see accelerometer
and MEMS speaker
MEMS technology is also used to make inkjet print heads, microactuators for read/write heads and all-optical switches that reflect light beams to the appropriate output port.
MEMS and MOEMS
When optical components are included in a MEMS device, it is called a micro-opto-electromechanical system (MOEMS). For example, adding a photonic sensor to a silicon chip constitutes a MOEMS device. See micromachine
, MEMS mirror
and optical switch
MEMS vs. Nanotechnology
Sometimes the terms MEMS and nanotechnology are used interchangeably because they both deal with microminiaturized objects. However, they are vastly different. MEMS deals with creating devices that are measured in micrometers, whereas nantotechnology deals with manipulating atoms at the nanometer level. See nanotechnology
MEMS-based Optical Switch
In an all-optical switch, MEMS mirrors reflect the input signal to an output port without regard to line speed or protocol. This technology is expected to be the dominant method for building photonic switches.
Microfabrica's EFAB builds MEMS devices one metal layer at a time. EFAB was the first MEMS foundry to quickly turn customers' CAD designs into micromachines. In this image, the square at the top is a microfluidics device used for a "lab on a chip." The multi-arm device (center) is a fuel injection nozzle. Bottom left (red arrow) is an accelerometer, and bottom right is an inductor used in RF circuits. (Image courtesy of Microfabrica Inc., www.microfabrica.com)
MEMSIC's dual-axis thermal accelerator is a MEMS-based semiconductor device that works conceptually like the air bubble in a construction level. The square in the middle of the chip is a resistor that heats up a gas bubble. The next larger squares contain thermal couples that sense the location of the heated bubble as the device is tilted or accelerated. (Image courtesy of MEMSIC, Inc.)