Definition
Micro-electromechanical systems (MEMS) is a technology that combines computers with tiny mechanical devices such as sensors, valves, gears, mirrors, and actuators embedded in semiconductor chips.




Overview
MEMS are already used as accelerometers in automobile air-bags. They've replaced a less reliable device at lower cost and show promise of being able to inflate a bag not only on the basis of sensed deceleration but also on the basis of the size of the person they are protecting. Basically, a MEMS device contains micro-circuitry on a tiny silicon chip into which some mechanical device such as a mirror or a sensor has been manufactured. Potentially, such chips can be built in large quantities at low cost, making them cost-effective for many uses.






Introduction
Among the presently available uses of MEMS or those under study are:

Global position system sensors that can be included with courier parcels for constant tracking and that can also sense parcel treatment en route .
Sensors built into the fabric of an airplane wing so that it can sense and react to air flow by changing the wing surface resistance; effectively creating a myriad of tiny wing flaps .
Optical switching devices that can switch light signals over different paths at 20-nanosecond switching speeds
Sensor-driven heating and cooling systems that dramatically improve energy savings .
Building supports with imbedded sensors that can alter the flexibility properties of a material based on atmospheric stress sensing .