What is MEMS ?
Micro-Electro-Mechanical Systems (MEMS) is the technology of the future, allowing microscopic devices to replicate the functionality of current large-scale systems, or even perform tasks previously unimaginable.
MEMS are either used as sensors or actuators, possibly operating in a wide range of physical domains spanning electrostatics, mechanics, piezo-electrics, thermodynamics, electromagnetics, fluidics, and optics. In all of these cases, they must be accompanied by electronic circuitry for control and/or monitoring.
Some MEMS applications are already well established in the market, such as inkjet printer heads and accelerometers for automobile airbag deployment. Some are becoming more and more common, such as the gyroscopes and microphones, and many are emerging such as new resonators for timing, MEMS for fuel cells, micro switches, microfluidics, etc.
Below is an excellent introduction video about MEMS, made available by the MEMS Industry Group™ (Link):