Transcript Energy Scavenging for Wireless Sensor Networks

Energy Scavenging and
Underwater sensors for
Wireless Sensor Networks
Curtis Alia
CMPE 491w
Energy Scavenging in Wireless Sensor Networks: Vibration Energy
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Conversion Methods
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Piezoelectric - charge separation (voltage across capacitor)
 Capacitive - capacitance changes, increasing charge/voltage
 Inductive - coil passes through magnetic field, creating electrical current
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Ideal for sensors located in proximity to machinery (industrial equipment,
household appliances, vehicles, etc.)
Capable of power ranging from 100-600µW/cm3 from a 2.25m/s2 vibration
source @ 120Hz
Has major advantages for lifetimes of over one year
Applications
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Tire monitoring – check inflation/tread ware/camber
Machine status readings – temperature, massive vibration, etc.
Health monitors – heart rate, blood pressure, sugar levels
Environmental controls – pH, pollution
Emergency Response – fire detection, water sprinklers
Although it produces more power, it is harder to implement than electrostatic
methods
Underwater Acoustic Sensor Networks
 Node placed underwater to retrieve data
 Nodes may be anchored and tied to ocean floor or elevated to a
fixed depth (depending on sensor’s functionality)
 Data is transmitted wirelessly to station located above water (buoy)
using an acoustic modem built into the sensor
 Acoustic Propagation
Path loss – acoustic energy converts to heat, or ocean waves spread
the sound energy
 Noise – acoustic interference from tides, etc. and/or machinery
 Multi-path – reflection of signal can cause severe distortion
 Propagation Delay – reduces throughput of system
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Code Division Multiple Access (CDMA) used to reduce number of
retransmitted packets, thus reducing power consumption
Sensor nodes’ hardware is currently expensive (acoustic modem,
water protection, etc.)
Can take readings of salinization, tides, tropical storm detection, etc.
Must be built in such a way to handle a wide range of temperatures
and withstand the harsh environment in which it will be placed
Harvesting References
http://www.media.mit.edu/resenv/pubs/pap
ers/2005-02-EHarvestingPervasivePprnt.pdf
 http://engnet.anu.edu.au/DEpeople/Shad.
Roundy/EnergyScavenging.ppt
 http://www.columbia.edu/cu/mechanical/ne
ws/seminars/022803.html
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Underwater References
http://users.ece.gatech.edu/tommaso/pape
rs/underwater.pdf
 http://www.ece.gatech.edu/research/labs/b
wn/UWASN/
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