What Is A Smart Dust?
'Smart dust' — sensor-laden networked computer nodes that are just cubic millimetres in volume. The smart dust project envisions a complete sensor network node, including power supply, processor, sensor and communications mechanisms, in a single cubic millimetre. .Smart dust motes could run for years , given that a cubic millimetre battery can store 1J and could be backed up with a solar cell or vibrational energy source .
The Mems Technology In Smart Dust
Smart dust requires mainly revolutionary advances in miniaturization, integration & energy management. Hence designers have used MEMS technology to build small sensors, optical communication components, and power supplies. Microelectro mechanical systems consists of extremely tiny mechanical elements, often integrated together with electronic circuitory. They are measured in micrometers, that is millions of a meter. They are made in a similar fashion as computer chips. The advantage of this manufacturing process is not simply that small structures can be achieved but also that thousands or even millions of system elements can be fabricated simultaneously. This allows systems to be both highly complex and extremely low-cost.
Active-Steered Laser Systems
For mote-to-mote communication, an active-steered laser communication system uses an onboard light source to send a tightly collimated light beam toward an intended receiver. Steered laser communication has the advantage of high power density; for example, a 1-milliwatt laser radiating into 1 milliradian (3.4 arcseconds) has a density of approximately 318 kilowatts per steradian (there are 4 steradians in a sphere), as opposed to a 100-watt lightbulb that radiates 8 watts per steradian isotropically. A Smart Dust mote’s emitted beam would have a divergence of approximately 1 milliradian, permitting communication over enormous distances using milliwatts of power. Each mote must carefully weigh the needs to sense, compute, communicate, and evaluate its energy reserve status before allocating precious nanojoules of energy to turn on its transmitter or receiver.
Abstract
Advances in hardware technology have enabled very compact, autonomous and mobile nodes each having one or more sensors, computation and communication capabilities, and a power supply. The Smart Dust project is exploring whether an autonomous sensing, computing, and communication system can be packed into a cubic-millimeter mote to form the basis of integrated, massively distributed sensor networks. It focuses on reduction of power consumption, size and cost. To build these small sensors, processors, communication devices, and power supply , designers have used the MEMS (Micro electro mechanical Systems) technology.
Major Challenges
1. To incorporate all these functions while maintaining a low power consumption
2. Maximising operating life given the limited volume of energy storage
Listening To A Dust Field
Many Smart Dust applications rely on direct optical communication from an entire field of dust motes to one or more base stations. These base stations must therefore be able to receive a volume of simultaneous optical transmissions. Further, communication must be possible outdoors in bright sunlight which has an intensity of approximately 1 kilowatt per square meter, although the dust motes each transmit information with a few milliwatts of power. Using a narrow-band optical filter to eliminate all sunlight except the portion near the light frequency used for communication can partially solve this second problem, but the ambient optical power often remains much stronger than the received signal power.
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