1. Smart Dust Communicating with a Cubic- Millimeter Computer

2. Table of Contents Introduction Background Basic Idea Technologies used
Current Scenario
Future Prospects
Conclusion

3. Introduction What is Smart Dust?
“Smart dust” devices are tiny wireless micro electro mechanical sensors (MEMS) that can detect everything from light to vibrations.
Also called “Motes”
These “motes” could eventually be the size of a grain of sand, though each would contain sensors, computing circuits, bi- directional wireless communications technology and a power supply.
Motes would gather scads of data, run computations and communicate that information using two-way band radio between motes at distances approaching 1,000 feet.
Sensors may include one or more temperature, pressure, vibration, acceleration, light, magnetic, or acoustic devices. Some of the more sophisticated sensors also include the ability to perform chemical analysis to identify airborne or liquid substances.

4. Continued…
Smart dust has wide range of applications in almost all fields. For example, the military can use them to gather information on battlefields, and engineers can mix them into concrete and use them to internally monitor the health of buildings and bridges.

5. Background
Conceived by Dr. Kris Pister of University of California Berkeley
The Defence Advanced Research Projects Agency (DARPA) was among the original patrons of the mote idea. One of the initial mote ideas implemented for DARPA allows motes to sense battlefield conditions.

6. THE BASIC IDEA
The “mote” concept creates a new way of thinking about computers, but the basic idea is pretty simple:
The core of a mote is a small, low-cost, low-power computer.
The computer monitors one or more sensors , including sensors for temperature, light, sound, position, acceleration, vibration, etc. Not all mote applications require sensors, but sensing applications are very common.
The computer connects to the outside world with a radio link that allows a mote to transmit at a distance of about 10 to 200 feet. Power consumption, size and cost are the barriers to longer distances. Since a fundamental concept with motes is tiny size, small and low-power radios are normal.

7. Continued…
Motes can either run on batteries, or they can tap into the power grid in certain applications. As motes shrink in size and power consumption solar power or even vibration power can be used to keep them running.
All of these parts are packaged together in a container of the size of a stack of five or six quarters, or the size of a pack of cigarettes. In the future, people imagine shrinking motes to fit into something just a few millimetres on a side. The battery is usually the biggest part of the package right now.

8. TECNOLOGIES USED Smart Dust combines the following three technologies:
Digital Circuitry
MEMS (Micro-Electro-Mechanical Systems)
RF (Radio Frequency) Wireless Communication Technology

9. Digital Circuitry Micro electronic integrated circuits can be thought of as the “brains” of a system and MEMS augments this decision- making capability with “eyes” and “arms”, to allow micro- systems to sense and control the environment. Because MEMS devices are manufactured using batch fabrication techniques similar to those used for integrated circuits, unprecedented levels of functionality, reliability, and sophistication can be placed on a small silicon chip at a relatively low cost.

10. MEMS SENSORS
Smart Dust devices use MEMS technology sensors. Micro-Electro- Mechanical Systems (MEMS) is the integration of mechanical elements, sensors, actuators, and electronics on a common silicon substrate through micro fabrication technology. The micro mechanical components are fabricated using compatible “micromachining” processes.
Sensors gather information from the environment through measuring mechanical, thermal, biological, chemical, optical or magnetic phenomena , electronics then processes the information derived from the sensors and through some decision making capability direct the actuator to respond by moving, positioning, regulating, pumping and filtering for some desired outcome or purpose.

11. Continued…
The material used in these sensors is an amorphous ribbon of alloy that is manufactured softly magnetic by quick cooling. Example, an alloy of iron, molybdenum, boron and silicon. Magnetically soft materials have no strong fixed magnetic field even though they contain iron . To use these strips as temperature and stress sensors, an activator must be passed near the sensor strips.
A simple loop that generates a magnetic field activates the sensors from a distance. This magnetic field is not blocked by any material on the road surface or concrete and is not altered by the presence of iron material. These simple sensor strips provide a consistent temperature reading. These sensors can also be immersed in water or other liquids and can provide not only temperature but also viscosity, liquid density and surface tension measurements.

12. WIRELESS COMMUNICATION
A wireless communication system is required for sending and receiving data from distributed sensor network or smart dust systems.
Available wireless communication architecture for smart dust satisfies a number of requirements.
It supports bi-directional communication between a central transceiver and up to 1000 dust motes. The downlink (central trans- receiver to dust motes) broadcasts to all of the dust motes at a bit rate of several kbps. The uplink (dust motes to central trans-receiver) permits dust motes to convey at about 1 kbps, an aggregate throughput of 1 Mbps.

13. Continued…
The central transceiver is able to resolve the position of each dust mote in an angular resolution of the order of one by hundredth of the field of view.
The link operates over a range of at least several 100 meters.
The dust mote transmitter occupies a volume of the order of one cubic millimetre and consumes an average power not exceeding one microwatt.
If possible uplink and downlink should afford a low probability of interception.

14. Operation of Motes
The mote includes sensing, computing, power, and communications sections . Volume puts a severe constraint on energy since we do not have much room for batteries or large solar cells. Thus, the motes must operate efficiently and conserve energy whenever possible.
Most of the time, the majority of the mote is powered off with only a clock and a few timers running . When a timer expires, it powers up a part of the mote to carry out a job, then powers off
A few of the timers control the sensors. When one of these timers expires, it powers up the corresponding sensor, takes a sample, and converts it to a digital word. If the data is interesting, it may either be stored directly in the SRAM or the micro controller is powered up to perform more complex operations with it. When this task is complete, everything is again powered down and the timer begins counting again.

15. Another timer controls the receiver
Another timer controls the receiver. When that timer expires, the receiver powers up and looks for an incoming packet. If it doesn’t see one after a certain length of time, it is powered down again .
In response to a message or to another timer expiring, the micro controller will assemble a packet containing sensor data or a message and transmit it using either the corner cube retro reflector or the laser diode, depending on which it has.

16. The communication can be in 3 ways-
Radio-Frequency Communications
Optical Communication: active dust mode transmitters
Optical Communication: passive dust mode transmitters

17. Radio-Frequency Communications
Radio frequency communication is one of the well-developed communication systems.
It is based on the generation, propagation and detection of electromagnetic waves with a frequency range from tens of kHz to hundreds of GHz.
It could be used to function as both the uplink and the downlink.

18. Radio-Frequency Communications
Pros
Long range
Line-of-sight path not required
Not severely affected by rain, fog or atmospheric turbulence
Cons
Antenna may be too large for dust motes
Requires modulator, demodulator, filtering (power consumption)
Requires complex multiplexing scheme (TDMA, FDMA, CDMA)

19. Optical Communication Active Dust Mote Transmitter
It uses an active steered onboard laser diode based transmitter to send a collimated laser beam to a station
It consist of a laser diode, collimating lens and beam steering mirrors for the communication
With the laser diode and the set of beam scanning mirrors, we can transmit data in any direction desired, allowing the mote to communicate with other Smart Dust motes.

20. Pros Cons Longer range than passive links (up to about 10 km)
Higher bit rates than passive links (up to about 1 Mbps)
With multi-hop, avoids need for every dust mote to have line-of-sight path to base station
Utilizes space-division multiplexing
Only baseband electronics are required
Cons
Requires protocol to steer directional transmitters
Requires higher power than passive transmitter
Affected by rain, fog, atmospheric turbulence

21. Optical Communication
Passive Dust Mode Transmitters

22. Corner Cube Reflector (CCR)
The base of the retro reflector is a MEMS flap that modulates the reflected beam
 One of the three mirrors mounted on a spring at an angle slightly a skew from perpendicularity to the other mirrors.
In this position, because the light entering the CCR does not return along the same entry path, little light returns to the source-a digital 0
Applying voltage between this mirror and an electrode beneath it causes the light entering the CCR to return to its source-a digital 1.

23. Continued…
A CCD video camera at the BTS sees the CCR signals as lights blinking on and off. It decodes these blinking images to yield the uplink data.
This technique is substantially more energy efficient than actually generating some radiation.

24. Pros Cons Dust motes need not radiate power, nor steer beam
Exploits asymmetry: powerful base station, low-power dust motes
Utilizes space-division multiplexing
Only baseband electronics are required
Cons
Requires line-of-sight path to base station
Short range (up to about 1 km)
Bit rate limited to about 10 kbps
Affected by rain, fog, atmospheric turbulence

25. Generations of Mote Golem Dust is solar powered with bi-directional
communications and sensing (acceleration and
ambient light). Shaped like a cubicle, the mote
is 11.7-cubic millimetres and could fit more than
a dozen on a penny.
Daft Dust is a little larger. At 63-cmm, it is a bi-
directional communication mote that is shaped
more like an upside-down bowl.
Flashy Dust is a 138-cmm unidirectional
communication and sensing (ambient light) mote.

26. Applications Environmental monitoring:
A farmer, vineyard owner, or ecologist could equip motes with sensors that detect temperature, humidity, etc.
Monitor power consumption of household appliances:
The motes would log power and water consumption for a customer. When a truck drives by, the motes get a signal from the truck and they send their data.
Measuring structural integrity of a building or any other structure:
The mote embedded into the concrete could have a sensor on it that can detect the salt concentration within the concrete or vibration, stress, temperature swings, cracking, etc.

27. Continued…
Habitat monitoring:
A biologist could equip an endangered animal with a collar containing a mote that senses position, temperature, etc.
Military Application : To detect truck movement in a remote area thousands of motes are scattered. When an enemy truck drives through the area the commander can track the path that the truck is following through the field of motes.

28. Cosmetics company monitoring warehouse humidity
Continued…
Out of range vibrations in industrial equipment to catch manufacturing defects
Hospital monitoring of patient movements / monitoring the elderly while allowing freedom of movement
Cosmetics company monitoring warehouse humidity
Health and Wellness Monitoring (enter human bodies and check for physiological problems).
Traffic sensors in urban areas

29. Environmental protection (identification and monitoring of pollution).
Continued…
Environmental protection (identification and monitoring of pollution).
Indoor/Outdoor Environmental Monitoring.

30. Advantages Physical attributes: Ad-hoc networking capabilities:
Small and lightweight
Low power consumption
Ad-hoc networking capabilities:
Networking functions are seamless and automatic
Multiple networks can be in use simultaneously
Data transmission capabilities:
On-board data acquisition supports many missions
Software support for many sensor configurations
Data can be carried through network to command centres
Ubiquity and redundancy in use:
Multiple motes can be available on every device/person
Motes can be strewn in large numbers

31. Ad-hoc network
All of the motes in the area create a giant, amorphous network that can collect data. Data funnels through the network and arrives at a collection node, which has a powerful radio able to transmit a signal many miles.
Used for monitoring purposes in military , traffic , habitat , environment , power consumption.

32. Disadvantages Low Throughput ( < 10 Kbps ) : Size : Cost
Suited for data monitoring, not real-time audio
Power Source :
RF communications circuits drain a lot of power
Need advancement in battery technology
Size :
Many components -> difficult to reduce size
Cost
Current motes cost between $50 - $100 each
Intrusive probes
A number of political, environmental, health and privacy related questions

33. Current scenario & future prospects
Honeywell International is looking at the motes for climate control applications.
San Jose, Calif.-based Digital Sun is receiving orders for wireless sensors that monitor irrigation.
Intel & Crossbow has come up with a second- generation operating system for the smart dust.
Researches indicate that motes sold in future will be smaller , cheaper and are likely to have revolutionary power sources.

34. Conclusion
There are many ongoing researches on Smart Dust, the main purpose of these researches is to make Smart Dust mote as small as possible and to make it available at as low price as possible. Soon we will see Smart Dust being used in varied application from all spans of life. .

35. References http://www.careers-india.com http://www.wikipedia.com

36. Thank You!