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Energy Harvesting Methodologies for Wireless Sensor Nodes

Energy Harvesting Methodologies for Wireless Sensor Nodes. Dinesh Bhatia Associate Professor Abhiman Hande Research Associate Erik Jonsson School of Engineering November 23, 2005. Outline. Present power requirements in PANs Necessity for alternate sources of energy

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Energy Harvesting Methodologies for Wireless Sensor Nodes

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  1. Energy Harvesting Methodologies for Wireless Sensor Nodes Dinesh Bhatia Associate Professor Abhiman Hande Research Associate Erik Jonsson School of Engineering November 23, 2005

  2. Outline • Present power requirements in PANs • Necessity for alternate sources of energy • Available alternative energy sources • Energy harvesting issues • Energy storage issues • Power management strategies • Research at UTD’s EACG

  3. Technology Trends Relative improvements in laptop computing technology from 1990–2003.

  4. Feasible Sources of Energy • Photovoltaic solar cells • Amorphous • Crystalline • Vibrations • Piezoelectric • Capacitive • Inductive • Radio-Frequency (RF) • Thermoelectric conversion • Human power • Wind/air flow • Pressure variations Power densities of energy harvesting technologies

  5. Feasible Devices for Energy Storage • Batteries • Li-ion • NiCD • NiMH • Ultracapacitors • Maxwell • Samsung • NEC • Micro-fuel cells • Micro-heat engines • Radioactive power sources VoltaFlex thin film rechargeable lithium batteries Maxwell 5V 2F 2.7 mAhr ultracapacitor

  6. Energy Harvesting for Wireless Sensor Nodes Energy source Energy harvesting and energy storage VCC Antenna RF communication link A/D converter Microcontroller Raw data Packetized samples Sensors Program and data flash memory Block diagram of an energy harvesting wireless sensing node with data logging and bidirectional RF communications capabilities

  7. Solar Cell Characteristics • 10-20 % efficiency outdoors • <1% efficiency indoors • Needs power management scheme • Maximum power point might need tracking V-I characteristics of a Solar World 4-4.0-100 solar panel

  8. Solar Cell Efficiencies Under Different Light Conditions

  9. Vibrations to Electricity

  10. Comparison of Vibrations to Electricity Methods • Scavenging the power from commonly occurring vibrations for use by low power wireless systems is both feasible and attractive for certain applications. • Piezoelectric converters appear to be the most attractive for meso-scale devices with a maximum demonstrated power density of approximately 200 μW/cm3 vs. 100 μW/cm3 for capacitive MEMS devices. • Electromagnetic converters provide maximum voltage of 0.1 volts

  11. Piezo Converter Set-up Piezoelectric converter with rectifier and DC-DC converter

  12. Power Management VCC to system Optional rectification Power Management Batteries Ultracapacitors • Charge energy storage devices • Route stored energy to sensor node • Monitor available energy level • Low power buck/boost converter required Solar panels / piezoelectric element Dual energy storage mechanism for a wireless sensor node

  13. Research at UTD’s EACG • CrossbowTM MICAz motes • 2.4GHz, IEEE 802.15.4 compliant ZigBeeTM transceiver. • Mesh networking protocol • Potential applications include temperature and light monitoring in remote locations, measuring tire pressure, monitoring acceleration in automobiles, medical applications, etc. MICAz mote MICA2 motes

  14. Battery Life Estimation for a MICAz Mote Battery life estimation for a MICAz mote operating at 1% duty cycle

  15. Research Challenges Task 1: Develop designs for energy scavenging prototypes Task 2: Develop an appropriate power management scheme Task 3: Identify appropriate components for procurement Task 4: Implement the prototype designs Task 5: Testing and modifications SP SU FA 2006 (Y1) SP SU FA 2007 (Y2) SP SU FA 2008(Y3) Indicates publications • Set-ups for both solar and vibrational energy • Dual energy storage scheme • Power management • Low power buck converter design Tentative research timeline

  16. Conclusions • Acceptable power sources remain perhaps the most challenging technical hurdle to the widespread deployment of wireless sensor networks. • While significant progress has been made in many areas including indoor photovoltaic systems, micro-fuel cells, thermoelectrics, micro-heat engines, and vibration-to-electricity conversion, much more research and new approaches need to be pursued.

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