A CDE Definition
A device that detects acceleration and tilt. Built using MEMS technology, accelerometers detect impact and deploy automobile airbags as well as retract the hard disk's read/write heads when a laptop is dropped. Digital cameras employ them in their image stabilization circuits. They are used in washing machines to detect excessive vibration and in pedometers for more accurate distance measurement. They also enable a handheld display to be switched between portrait and landscape modes when the unit is turned.
Springs, Bubbles, Capacitance and Crystals
MEMS accelerometers initially used a microminiaturized cantilever-type spring, which converted force into a displacement that was measured. Subsequent MEMS devices use a heated gas bubble with thermal sensors that functions like the air bubble in a construction level (see MEMS). Other types of accelerometers use microstructures that change their capacitance or microscopic crystals that generate a voltage when stressed.
Accelerometers, Gyroscopes and Magnetometers
An accelerometer measures a change in velocity and position, whereas a gyroscope measures rotational changes, and a magnetometer measures compass direction. All three are used in an "inertial measurement unit" (IMU) in airplanes, spacecraft and satellites, and mobile devices use accelerometers and magnetometers.
Dual-Axis Thermal Accelerometer
An iPhone Level
(MicroElectroMechanical Systems) 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).
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, DLP and optical switch.
MEMS Vs. Nanotechnology
Sometimes MEMS and nanotechnology are terms that 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.
MEMS-based Optical Switch
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