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

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 µW/cm 3 from a 2.25m/s 2 vibration 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

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 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 ers/ E- HarvestingPervasivePprnt.pdf ers/ E- HarvestingPervasivePprnt.pdf Roundy/EnergyScavenging.ppt Roundy/EnergyScavenging.ppt ws/seminars/ html ws/seminars/ html

Underwater References rs/underwater.pdf rs/underwater.pdf wn/UWASN/ wn/UWASN/