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 and Bubbles
MEMS accelerometers initially used a microminiaturized cantilever-type spring, which converts force into a displacement that can be measured. Subsequent accelerometers use a heated gas bubble with thermal sensors and function much like the air bubble in a construction level. When the accelerometer is tilted or accelerated the sensors pick up the location of the gas bubble. See MEMS.