Smart Dust12BTCSE051

Anurag Srivastava

Introduction Smart Dust concept has been credited to researchers at the University of California,

Bekerley in 1997 by Prof. Kris Pister.

Smart Dust is a self-contained network of tiny motes each having the capability of

sensing and monitoring the environment conditions.

Often called micro electro-mechanical sensors (MEMS).

They contain sensors which have the computational capability.

They can communicate with a base station or with other motes depending on

the application.

Smart Dust Motes

ArchitectureSmall Smart Dust Has -

A semiconductor laser diode and MEMS beam steering mirror for

active optical transmission.

A MEMS Corner Cube Retro-reflector (CCR) for passive optical

transmission.

An optical receiver.

A signal processing and control circuitry.

A power source based on thick-film batteries and solar cells.

SMART DUST COMPONENTS

MEMS Designers have used MEMS technology to build small sensors, optical

communication components and power supplies.

MEMS consists of extremely tiny mechanical elements, often integrated

together with electronic circuitry.

They are measured in micrometers that is millions of a meter. They are made

in a similar fashion as computer chips.

CCR CCR comprises three mutually perpendicular mirrors of gold-coated poly

silicon.

The CCR has the property that any incident ray of light is reflected back to the

source.

If one of the mirrors is misaligned, this retro-reflection property is spoiled.

CCR

Working Smart dust motes run by a microcontroller.

Microcontrollers consist of tiny sensors for recording various

types of data.

Sensors run by timers. 

Data is sent to the base controlling station

Corner Cube Retro-Reflectors (CCR) built using MEMS

technique

Major Challenges It is difficult to fit all these devices in a small Smart Dust both size wise and

Energy wise.

As the devices are so small, batteries present a massive addition of weight.

High power consumption.

Complicated design and mechanism.

Communication Technologies

Radio Frequency Transmission

Optical transmission technique :

a) Passive Laser based Communication

b) Active Laser based Communication

c) Fiber Optic Communication

Radio Frequency Transmission

Based on the generation, propagation and detection of electromagnetic waves

with a frequency range from tens of kHz to hundreds of GHz.

Multiplexing techniques: time, frequency.

Their use leads to modulation, band pass filtering and additional circuitry, all

of which needs to be considered, based on power consumption.

Passive Laser based Communication

Downlink communication - the base station points a modulated laser beam at a

node. Dust uses a simple optical receiver to decode the incoming message.

Uplink communication - the base station points an un-modulated laser beam at

a node, which in turn modulates and reflects back the beam to the BST.

Active Laser based Communication

Has a semiconductor laser, a collimating lens and a beam-steering micro-

mirror.

Uses an active-steered laser-diode based transmitter to send a collimated laser

beam to a base station .

Suitable for peer-to-peer communication, provided there exist a line of sight

path between the motes.

Fiber Optic Communication

Employs semiconductor laser, fiber cable and diode receiver to generate,

transfer and detect the optical signal.

Similar to passive optical communication .

Relatively small size of the optical transceiver is employed with low-power

operation.

CCR employed on each Dust mote to modulate uplink data to base station.

Application

Security and Tracking Health and Wellness Monitoring (enter human bodies and check for

physiological problems). Factory and Process Automation. Seismic and Structural Monitoring. Monitor traffic and redirecting it. Exploring of planets. Detecting onset of diseases like cancer.

Advantage

Small Size

Better Connectivity

Low Cost

Useful in monitoring real world phenomenon without disturbing the original

process.

Disadvantages The main concern is privacy. Because it is so tiny, this device can be used to

spy on people without their approval.

The air currents can also move them in the direction of flow.

Conclusion Smart dust is made up of thousands of sand-grain-sized sensors that can measure

ambient light and temperature. The sensors -- each one is called a "mote" -- have

wireless communications devices attached to them, and if you put a bunch of them near

each other, they'll network themselves automatically.

Soon we will see Smart Dust being used in varied application from all spans of life.

References

J. M. Kahn, R. H. Katz, K. S. J. Pister: Next Century Challenges: Mobile Networking for

“Smart Dust”

An Introduction to Micro electro mechanical System Engineering: Nadim Maluf, Kirt

William

B.A. Warneke, M.D. Scott, B.S. Leibowitz: Distributed Wireless Sensor Network

http://www.coe.berkeley.edu/labnotes

http://www.webopedia.com

http://www.google.com