Energy Scavenging and Underwater sensors for Wireless Sensor Networks

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Energy Scavenging and Underwater sensors for
Wireless Sensor Networks
Curtis Alia CMPE 491w
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Energy Scavenging in Wireless Sensor Networks
Vibration Energy

• Conversion Methods
• Piezoelectric - charge separation (voltage across
  capacitor)
• Capacitive - capacitance changes, increasing
  charge/voltage
• Inductive - coil passes through magnetic field,
  creating electrical current
• 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 _at_ 120Hz
• Has major advantages for lifetimes of over one
  year
• Applications
• 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

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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 sensors
  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
• 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

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Harvesting References

• http//www.media.mit.edu/resenv/pubs/papers/2005-0
  2-E-HarvestingPervasivePprnt.pdf
• http//engnet.anu.edu.au/DEpeople/Shad.Roundy/Ener
  gyScavenging.ppt
• http//www.columbia.edu/cu/mechanical/news/seminar
  s/022803.html

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Underwater References

• http//users.ece.gatech.edu/tommaso/papers/underwa
  ter.pdf
• http//www.ece.gatech.edu/research/labs/bwn/UWASN/