Chapter 18 - Novel RFID TechnologiesEnergy Harvesting for Self-powered Autonomous RFID

Systems

Figure 18.1 Micro-Wireless Dot™ - Courtesy, Axcess International

LF Coil100 - 150

kHz

Antenna860-960

MHz

Antenna315/433

MHz

EnergyAware

Processor

ProtocolAdaptiveFirmware

System-on-a-Chip

SerialPorts

Power Management

NVMemory

ADCDAC

SerialBus

Near-FieldLoad Modulation

Far-FieldTransceiver

Far-FieldBackscatter

GPIO

Table 18.1 RFID/Sensor life time

3 V100 µW

33.33 µA

40 ms4.8 mA

0.000576 Watt-sec200

8 sec0.12 Watt-sec

10 µA

86392 sec2.59 Watt-sec2.71 Watt-sec

7.52 hrs

Energy necessary for transmissions

Energy necessary for idle conditions/day

Current available from vibrations (i source )

Axcess Tag powered by batteryPower available from vibrations

Transmission of ID to receiver takesCurrent draw during transmission (i active )Energy necessary/transmission

Time required to gather this energy from vibrations/day (t 3 )

Number of transmissions/day

Idle state current draw (i sleep )

Idle state time/day (t 1 )

Total energy reqd (idle+transmission)/day

Transmission time/day (t 2 )

Figure 18.2 Block diagram of an EH sensor

EnergySource

EnergyTransducer

EnergyStorage

VoltageRegulator

A/DConverter

Processor

EnvironmentalSensor

WirelessTransceiver

PGM/DataMemory

Energy Harvesting Wireless Sensor

Power Management

Energy Storage

Energy Transducer

Table 18.2 Power densities of EH technologies

Energy Harvesting Source

Power Density (µW/cm3)

Information Source

Solar (Outdoors)15,000 - Direct Sun 150 - Cloudy Day

Commonly Available

Solar (Indoors) 6 - Office Desk ExperimentsVibrations 100 - 200 Roundy et. al.

Acoustic Noise 0.003 @ 75 dB 0.96 @ 100 dB

Theory

Daily Temp. Variation 10 TheoryTemp. Gradient 15 @ 10oC Stordeur & Stark, 1997Piezo Shoe Inserts 330 Starner, 1996

Figure 18.3 EH system for solar cells

DC-DC Converter

CsS1Load

Switching converter (buck or buck-boost) or Switched capacitor converter

Secondary battery (Thin film, lithium, NiMH, etc.) or Ultracapacitor

Figure 18.4 Solar panel V-I characteristics

1

10

100

1000

10000

100000

0 1 2 3 4 5 6

Cu

rren

t (u

A)

Voltage (V)

Full Sun (95000 lx)

3300 lx

300 lx

Figure 18.5 DC-DC buck-boost converter for solar EH

Figure 18.6 A thermoelectric transducer VI characteristics

Figure 18.7 Types of Vibration EH Transducers

ElectrostaticChange in capacitance causes either voltageor charge increase.

Shad Roundy et . al., 2002 Shad Roundy et. al., 2004

PiezoelectricStrain in piezoelectricmaterial causes a charge separation (voltage acrosscapacitor)

Vs

C Rs

Piezoelectric generator

ElectromagneticCoil moves through magnetic field causing current in wire.

Amirtharajah et. al., 1998

Figure 18.8 Piezoelectric conversion modes

Table 18.3 Common vibration sources

Vibration SourcePeak

Frequency (Hz)

Acceleration (m/s2)

Car Engine Compartment 200 12Base of 3-axis machine 70 10Door Frame (after door closes) 125 3Small Microwave Oven 121 2.5HVAC Office Vents 60 0.2 - 1.5Windows on Busy Road 100 0.7CD in Notebook PC 75 0.62nd Story Floor in Busy Office 100 0.2

Figure 18.9 Cantilever characteristics

Figure 18.10 Block diagram of a vibration energy harvesting system

Piezo-electric vibration

transducerVs Rectifier

DC/DCConverter

Load (Battery)

Csource Rsource

Vrect+

-Vbat

+

-

Figure 18.11 DC-DC buck-boost converter with battery load

VB1C1Vrect

+

-

Q1

Vctrl

VC2 C2L

D1

-

+B1

Irect Ibat

Figure 18.12 Vision for EH based Micro-Wireless Dot™ sensor

Flex Circuit Antenna, Circuit Wiring

RF TransceiverCoils

Printed Passive Components

Barcode Label, Graphics, or Thin Film Solar Energy Harvesting Film

Thin-Film Renewable Charge Reservoirs

Piezoelectric MEMS Array & Wiring

Power Management

Figure 18.13 : Top view of the electrode patterns for cantilevers

of different sizes

Figure 18.14 MEMS cantilever – Courtesy, Texas MicroPower Inc

Table 18.4 Comparison of power densities

Author Device Effective Area (mm2)

Power, (μW)

Power density, (μWinch-2)

Power density, (μWinch-2g-1)

A (g) f (Hz)

Kim et al d33 PZT cantilever 0.0442 1 14596.41 1351.52 10.8 13.7k Shen et al d31 PZT cantilever 1.92 2.15 722.45 361.22 2.0 462.5 Marzencki et al d31 AlN cantilever 3.8 0.038 6.45 12.90 0.5 204 Jeon et al d33 PZT cantilever 0.027 1.01 24133.81 2234.61 10.8 13.9k Fang et al d31 PZT cantilever 0.1992 2.16 6995.72 6995.72 1.0 608 Marzencki et al d31 AlN cantilever 0.552 1.97 2302.48 575.62 4.0 1368 Renaud et al d31 PZT cantilever 1.845 40 13987.24 7361.70 1.9 -

Figure 18.15 Adaptive multi-source power management architecture

Optional Rectification

Tranducer DC/DC Converter

Energy Storage Device

PWM Controller

Solar/Vibrations/ Thermal, etc.

AC/DC Conversion

Vrect, Irect Vbat, Ibat

Rechargeable battery, Ultracapacitor, etc.