Micro-electro-mechanical systems [MEMS] is the integration of mechanical elements, sensors, actuators, and electronics on a common substrate through the utilization of microfabrication technology.

MEMS devices are considered to range in characteristic length from one millimeter down to one micron – many times smaller than the diameter of a human hair.

MEMS will often employ microscopic analogs of common mechanical parts and tools; they can have channels, holes, cantilevers, membranes, cavities, and other structures. However, MEMS parts are not machined. Instead, they are created using micro-fabrication technology similar to batch processing for integrated circuits.

Many products today use MEMS technology, such as micro heat exchangers, inkjet printer heads, micro-mirror arrays for high-definition projectors, pressure sensors, infrared detectors, and many more.

MEMS devices

1) Airbag:

• Depending on crash, severity the rate of which the airbags are deployed is decided by the air bag control unit.

• In the event of a crash the balance. forcMicroelectromechanical systems (MEMS), also known as microsystems technology in Europe, or micromachines in Japan, are a class of devices characterized both by their small size and the manner in which they are made. MEMS devices are considered to range in characteristic length from one millimeter down to one micron – many times smaller than the diameter of a human hair.

• This control unit triggers the inflation device which generates nitrogen gas by igniting a mixture of sodium azide [Na $N_3$] and potassium nitrate [ x $NO_3$]

• The time between crash detection and complete deployment of air bag is approximately 0.05 seconds. The airbag speed is about 200 mph.

2) DMD: Digital micromirror device

• In DMD light modulator, we take an optical analog input and convert it into a digital format.

• It uses optical sensors and optical equipments.

• DMD chip has on its surface several hundred thousand microscopic mirrors arranged in a rectangular array which correspond to the pixels in the image to be displayed.

• The mirror can be individually rotated ± 10 - $12^o%$ to an ON or OFF state.

• In ON state light from the projector bulb is reflected into the lens making the pixel appear bright on the screen.

• In the OFF state the light is directed elsewhere [usually onto a heat sink] making the pixel appear dark.