Smart dust consists of tiny sensor-equipped motes that can monitor environments through sensing conditions and communicating wirelessly. The motes contain MEMS components like sensors, optical communication tools, and solar cells. They face challenges with size, weight, power consumption, and complexity. Communication occurs through radio frequency, passive laser beams using retroreflectors, or active laser transmission depending on the application and environment. Potential applications include security, health monitoring, automation, and environmental monitoring.

1. Smart Dust
12BTCSE051
Anurag Srivastava

2. 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.

3. Smart Dust Motes

4. Architecture
Small 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.

5. SMART DUST COMPONENTS

6. 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.

7. 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.

8. CCR

9. 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

10. 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.

11. Communication Technologies
 Radio Frequency Transmission
 Optical transmission technique :
a) Passive Laser based Communication
b) Active Laser based Communication
c) Fiber Optic Communication

12. 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.

13. 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.

14. 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.

15. 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.

16. 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.

17. Advantage
 Small Size
 Better Connectivity
 Low Cost
 Useful in monitoring real world phenomenon without disturbing the original
process.

18. 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.

19. 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.

20. 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