Micro Energy Harvesting - BFH · with a certain level of reliability, ¨on-time, failure rate, .....

Micro Energy Harvesting

- Overview of Harvesting Techniques -

.... with a few future perspectives and recent solutions

Peter WoiasAlbert-Ludwigs-Universität Freiburg

2010: solar powered camel

2020 ?g gDept. of Microsystems Engineering (IMTEK)

Laboratory for Design of MicrosystemsFreiburg Germany

Sheet 1Peter Woias Energy Harvesting Seminar, FTI Biel, 27.10.2010

Freiburg, Germany

MicroMicro energyenergy harvestingharvesting –– IMTEK‘sIMTEK‘s PhDPhD programprogram

Fact sheetfinanced by DFG and industry

Research topicsenergy transduction mechanismsfinanced by DFG and industry

3 associated members22+1 PhD scholarhips

energy transduction mechanismsmaterials for energy harvestingenergy storage and management

start: October 2006run-time: 4.5 years (1st phase)

d h 2011 2015

system considerations

second phase: 2011-2015

Associated Members Members Sponsorsp

?


Ph.DPh.D. . studentsstudents, , supervisorssupervisors andand industrialindustrial partnerspartners

Workshop, 14.-15.January 2010, Freiburg


Distributed Distributed andand embeddedembedded ((MicroMicro))systemssystems

wireless data linkBuilding and Enviroment Medical

Space, ….

sensor input

micro-sensor

wireless transmitter

micro-controller

S TMS TMS TMS TM

S TM S TM S TM

S TMS TM… powersupply ?

S TM

S TMS TM

S TM G

TMFabrication and Transport

S TMSensorData processing

SM

Gateway


CommunicationTAutomotive

Power Power supplysupply ofof distributeddistributed andand embeddedembedded systemssystems

wireless data link

sensor input

micro- wireless

p

micro-sensor transmittercontroller

energy management

battery mains adapterpower grid


WireWire oror batterybattery ??

rope

distributed and „embedded“ sensor sensorsystems in greenhouses © Crossbow

tire pressure sensors

Sensors in redwood trees

medical implants© Vitatron

battery service person(vertigo-proof)


Sensors in redwood trees© University of California

The Vision: The Vision: MicroMicro EnergyEnergy HarvestingHarvesting

Energy-Autonomous Embedded Systems always on“

wireless data link

sensor input

„always onno battery recharging or exchangeno power cords

micro- wireless

sensor input

micro-

easy to install …… at numerous application sites

microsensor


microcontroller

energy management

generator energy storage

heat,light

movement,th bG h li t


other bugs,…Graphosoma lineatum

Micro-Embedded Systems and Micro Energy HarvestingMicro Energy Harvesting

How ? energy andsystem

management

energy materials

and

management

gyconversion energy

storage


AmbientAmbient energyenergy andand relatedrelated conversionconversion mechanismmechanism

energy from electromagnetic, electromagnetic

field energymechanical orfluid motion

capacitive, EHD, MHD

piezoelectric capacitive (electret)

(Carnot) cycleinduction

thermalenergy

capacitive (electret) inductive (P-magnet) optical

energy

electrical

thermoelectricphotovoltaic

chemicalenergy

electricalenergyfuel cells


PiezoelectricPiezoelectric generatorsgenerators

Piezoelectric constants of several relevant materialsseveral relevant materials

d31 d33 [pC/N]

PZT 350 680

: σ= dqmodevertical

PZT - 350 680LiNbO3 -0,85 6PVDF 6..10 13..22

Properties

33333: σ⋅= dqmodevertical

charge deliveryAC currents only via a dynamic mechanical loadingdynamic mechanical loadingfair to high voltages (1…100 V)moderate to high source i d (10 100 kΩ)

11313: σ⋅= dqmodeltransversa


impedance (10 …100 kΩ)

PiezoelectricPiezoelectric bendingbending generatorsgenerators: : PrinciplePrinciple

11,31 piezodq σ⋅= ( )1131 σ⋅== dtd

dtdqdI

Design challengesh h i l t hi h t thomogeneous mechanical stress higher output powersmart system integration cheaper, easier fabricationtunable resonance frequency broader application range, more power


u ab e eso a ce eque cy b oade app ca o a ge, o e po e

ExamplesExamples ofof beambeam--type (type (bimorphbimorph) ) generatorsgenerators

P = 0,45 mW @ 1g and 60 Hz17,5 mm

50 mm

S. Roundy et al.,

Pmax = 0,08 mW @ 0,23 g and 120 Hz „Joule Thief“© AdaptivEnergy, before 2009

UC Berkeley, 2004

all mono-resonant !University of Singapore, 2003


yPmax = 0,64 mW

ElectromagneticElectromagnetic generatorsgenerators: : PrinciplePrinciple andand examplesexamples

rotor

d Φ

generator

multi-resonant generatorUniv Hongkong 2002

P = 800 µWtd

dNU Φ⋅−=

Univ. Hongkong, 2002batteryelectromechanic

quartz clockworkProperties

rotatory generator of the Seiko KineticTM wrist watch

P = 5 µWpAC currents from motion or induced AC fieldsbad to fair voltage range (mV…V)moderate source impedance (<10 kΩ)


Seiko KineticTM wrist watchmoderate source impedance (<10 kΩ)

„„ParasiticParasitic“ “ biomechanicalbiomechanical generatorsgenerators

MIT Media LabP = 0 25 W© Bionic Power

Burnaby Canada 2008P = 5 W

MIT Media Lab, Boston, USA, 1998

P = 0,25 WBurnaby, Canada, 2008© Bosch, ca. 1930

P = 3 W


P = 3 W

„Non„Non--parasiticparasitic“ “ biomechanicalbiomechanical generatorsgenerators

© Freeplay Energy, UK, 2003crank-powered radio

© Martijn Pater TU Delft NL 2000„Pullman“ MP3-Player

© Chris Aimone and Tomek Bartczak,

„REGEN“ MP3-Player


© Martijn Pater, TU Delft, NL, 2000 Toronto, Canada, 2003

CapacitiveCapacitive generatorsgenerators: : PrinciplePrinciple

PropertiesA AC currents from a dynamic change

of capacitancesome need an auxiliary voltage

kx

k

U

AQ

y gfair voltage range (V)very high source impedance (> 1 MOhm)

kd0

ε

UCQUdQWd

⋅=⋅=

( ) 2maxminmax2

1 UCCW ⋅−⋅=⇒


2

CapacitiveCapacitive generatorsgenerators: : ExamplesExamples

P = 24 µWImperial College, London, UK, 2003

UC Berkeley USA 2002Elastomer generator © DARPA, SRI

Pmax = 24 µW

Pmax = 300 mWUC Berkeley, USA, 2002

Pmax = 7

Pmax 300 mW

Pmax 7 µW


ThermoelectricThermoelectric generatorsgenerators (TEG): (TEG): PrinciplePrinciple

Seebeck coefficients ofl t t i l bi tirelevant material combinations

α [10-6 V/K]

Al / p-Poly-Si 195p yAl / n-Poly-Si 110p-Poly-Si / n-Poly-Si 190...320p-Bi0,5Sb1,5Te3 / n-Bi0,87Sb0,13 200...420

TU ΔΔ αProperties

DC-like currents, however…l it h ith th di ti f th t t fi ld

TU Δ⋅=Δ α

polarity changes with the direction of the temperature fieldlow to fair voltages (100 mV … V)low to high load resistance (Ohm … MOhm)


g ( )

ThermoelectricThermoelectric generatorsgenerators: : ExamplesExamples

polysiliconpolysilicon

FOXcavity

polysilicon

oxideili b t t

cavity

micro-TEG in planar CMOS

cavitysilicon substrate

P = 1 µW/cm² @ ΔT = 5 K

micro-TEG from (1994) for the „Seiko Thermic“ ( ld i ll b f 1998 )

micro-TEG in planar CMOS © Infineon, 2003P = 3 µW/cm² @ ΔT = 1..3 K

(sold in small numbers from 1998 on)

Micro Peltier cooler (photo) and micro


Micro Peltier cooler (photo) and micro-TEG (SEM) © FhG-IPM, MicroPelt

OurOur ownown 3D 3D micromicro--TEGTEG

top heat conductor (gold)

thermal isolator (SU-8)

air chamberair chamber for thermal insulation

bottom heat conductor (silicon)

membrane with planar thermocouples (Al-poly-Si)


T. Huesgen et al., Sensors & Actuators A 145-146, 2008, 523-429.

Bio fuel cellsBio fuel cells

P = 4 µW/cm²

direct-oxidizing glucose fuel cell enzymatic bio fuel cell

Sony 2007

S. Kerzenmacher et al., Journ. Power Sources, 2008A Kloke et al Proc Biosensors 2008 Shanghai

Sony, 2007

A. Kloke et al., Proc. Biosensors 2008, Shanghai

PropertiesDC current from catalytic oxidation of aDC current from catalytic oxidation of a„bio fuel“ by metals, enzymes or bacterialow voltages (0.1 … 0.5 V)


ECOBOT II © Univ. Bristol, UKpower in the µW … mW range

Energy densities of various storage conceptsEnergy densities of various storage concepts

10010.000

hydrogen in metal hydrides (MH)

60

80

100

ienc

y [%

]

NiMHLi-Ion

H2 in MH (< 2%)

H2 in MH (4%)

H2 in MH (nanopowder) Methanol

1.000

[Wh/

l]

20

40

Fara

day

effic

i

Lead Acid

Adenosine

NiMH

100

y de

nsity

in

batteries0

F

Gold

Cap

Ni-M

H

Li-Io

nH2

fuel

cell

ectro

lyzer

Gold Cap Triphosphate

Electrolyte Cap.

1

10

ener

gy

capacitors

G H2 Ele

1 10 100 1.000 10.000

energy density in [Wh/kg]

Refs: J. Brodd et al, J. Electrochem. Soc., 151 (3), 2004, K1-K11 and HERA


Hydrogen Storage Solutions, Germany

Energy managementEnergy management

Requirementsoptimal impedance match between

Solutions, chips ? ….not available todayoptimal impedance match between

generator, battery and loadvoltage level transformation

available today

(2004).

active generator controlactive rectificationsupply voltage: << 1 Vpp y gpower consumption: a few µW (max.)

Solutions microchips ? not available

2163 µm

Solutions, microchips ?..... not availabletoday ( 2004).

control ASIC for a capacitivemicro converter, Medinger,

Ph. D. thesis, MIT, and

….eventuallycoming along

(2007)


Analog Devices, 1999(2007).

Commercial Commercial low voltage steplow voltage step--up convertersup converters

2,5

3

]

charge pumpsinductor-based

1,5

2

p vo

ltage

[V]

0,5

1st

art-u

p

2005: 0 3 V

1998: 1.0 V

01970 1980 1990 2000 2010

year

2005: 0.3 Vphotovoltaic cell, TE generator


Resonant Resonant lowlow--voltagevoltage stepstep--upup convertersconverters

Historic example: 1-cell photoflash converter

Low voltage“„Low voltage“(1,5 V in 1988)

Fuji Quicksnap flashFuji Quicksnap flash(1988) product flyer

Principletransistor-transformer oscillatortransistor-transformer oscillatorself-resonantup-conversion ratio defined b th t f t ti 1


by the transformer turns ratio n:1

DiscreteDiscrete resonant resonant lowlow voltagevoltage stepstep--upup modulesmodules

Modern example: Enocean Perpetuum ECT 300

© Enocean


A A fewfew wrongwrong ideasideas aboutabout MicroMicro EnergyEnergy HarvestingHarvesting……

„ Micro Energy Harvesting will stop the climate change.“

„ Micro Energy harvesting is - on a small scale - the same aswe do with regenerative energies - on a large scale.“

„ Energy harvesting is nothing else thanreplacing the battery with a generator “

I have a sensor that requires 24 V and 50 mA

replacing the battery with a generator.

„ I have a sensor that requires 24 V and 50 mA. If you can supply that, we will use energy harvesting.“

„ The 100 µW that you deliver with your harvesterwill not be sufficient for our system. Forget about it.“


BetterBetter: : WhatWhat do do wewe wantwant toto accomplishaccomplish withwith itit ??

In general:

We do NOT want an excellent „Micro Energy Harvesting“ system,

we have to design an „Energy-Autonomous Embedded System“

Requirements from the customer and user

a certain system function, data rates, transmission distances, ….

with a certain level of reliability, on-time, failure rate, ..

under several constraints costs, lifetime,…

at a certain application site power levels, robustness, material choice…


LessonsLessons fromfrom NatureNature

wireless data linkLife is a perfect example for energy-autonomous embedded systems

sensor input

energy autonomous embedded systems

1. high adaptivity

2 ffi i t t

micro- wireless

sensor input

micro-

2. efficient energy storage

3. „wise“ system operationmicrosensor


microcontroller

What can we learn from nature ?

energy managementfrom nature ?

heat,light

movement,th b

generator energy storage


other bugs,…Graphosoma lineatum

„„AdaptivityAdaptivity“ “ forfor multiple multiple andand variable variable energyenergy resourcesresources

Heat Lightexample: JPL‘s „Power Tile“

Heat Light

otherother Bugs …

f I t t d S l E H ti d St D i NASA T h B i f J 2004


ref: Integrated Solar-Energy-Harvesting and Storage Device, NASA Tech Briefs, Jan. 2004

(Adaptive) (Adaptive) piezoelectricpiezoelectric generatorsgenerators

Principle: Direct piezoelectric effectcharge displacement in a nonsymmetric

mechanicalenergyg p y

crystal lattice, obtained via a mechanical deformation of the piezoelectric material

mechanicaldeformation

chargechargedisplacement

electricalenergy

Perovskite crystal structure of standard piezoceramic material (h PbZ Ti PZT d B Z Ti)


energy(here PbZrTi or PZT and BaZrTi)

ShapeShape--optimizedoptimized piezopiezo generatorgenerator

E Just et al Proc GMM-WorkshopE. Just et al., Proc. GMM-Workshop “Energieautarke Mikrosysteme”, 2006

F. Goldschmidtböing, P. Woias,

spectral output power (no seismic mass) influence of a seismic mass

g, ,Journ. Micromech. Microeng. 18, 2008, 104013


FrequencyFrequency--tunabletunable piezopiezo generatorgenerator

PrincipleActuation force in the „arms“ will stiffen the resonating beam and

force

gthus change its resonance frequency

high tuning range (22%)loss of Q factor withloss of Q factor withincreasing force

C Eichhorn et al Proc PowerMEMS 2008


C. Eichhorn et al., Proc. PowerMEMS 2008, Sendai, Japan, 309-312.

FrequencyFrequency--tunable generator systemtunable generator system

force

Fundamental questionsHow often will a „re-tuning“ be required ?How often will a „re tuning be required ?Will the tuning operation itself „eat“ all the harvested power ?If so, how to avoid this ?


C. Eichhorn et al., Proc. PowerMEMS 2010, Leuven, Belgium, accepted for publication

QuasiQuasi--staticstatic tuningtuning ofof piezoactuatorspiezoactuators

1. untuned

piezoactuator

ΔL2. fast tuning

effect of relaxation on theharvested power vs timeharvested power vs. time

3. slow relaxation slow dischargeAdvantages

i t t tpiezoactuator stores charge and positiononly slow relaxation


due to leakage currents

System characteristicsSystem characteristics


Output power in tuned and un-tuned operation (tuning intervals: 20 sec.)

FabricationFabrication: : PiezoPiezo--PolymerPolymer--CompositesComposites

vent

molding form

feed

molding form

piezodisk

molding form

piezoceramic diskwith metal electrodes

electrical contact

molding form

liquidthermosettingpolymer

20 mmpolymer layer

mounting block

p y y

seismic massvibration

piezo disk cured polymer

Advantagesstructure definition and piezo integration in onesingle stepg plow-cost perspective via inject moldingextremely high design flexibility


actuators and generators in a single technology

EfficientEfficient energyenergy storagestorage

today mostly electricslowly emerging alternatives ( th l) 10 000

Hydrogen in metal hydride

(e.g. thermal)design conflict between storage capacity, size/weight

Li Ion

H2 in MH (< 2%)

H2 in MH (4%)

H2 in MH (nanopowder) Methanol

1.000

10.000

Wh/

l]

and lifetime (always)Lead Acid

NiMHLi-Ion

100

dens

ity in

[W

RequirementsGold Cap

Adenosine Triphosphate

Electrolyte Cap.

10

ener

gy d batteries

capacitors

good Faraday efficiencyappropriate size, weight, and capacity

11 10 100 1.000 10.000

energy density in [Wh/kg]

p yappropriate cycle numberfor charge/dischargesmall self-discharge and losses

Refs: J. Brodd et al, J. Electrochem. Soc., 151 (3), 2004, K1-K11 and HERA Hydrogen Storage Solutions D

small self-discharge and lossessmall ageing effectsothers (e.g. temperature tolerance)


Hydrogen Storage Solutions, D

Low Low leakageleakage electrolyticelectrolytic capacitorscapacitors

Example: Vishay BCcomponents 013 RLCIL as function of UC

( )[ ] [ ] [ ]( )greateriswhichever

µAorµFCVUµAI RR 7.0002.0min20 ⋅⋅<

( )ecapacitancratedC

VvoltageratedU

R

R

:25...3.6:

IL as function of timeResults

leakage current falls with the applied voltageleakage current falls with the applied voltageleakage current falls with time

0.3

„Keep your capacitorlarge enough and full enough“


120 s

Low Low leakageleakage electrolyticelectrolytic capacitorscapacitors

Loss calculation

E l Vi h BC t 013 RLC

IL as function of UC

Example: Vishay BCcomponents 013 RLC

rated values: 100µF/10V

Assumptions: The capacitor has to buffer a DC voltage of 2.3 V. The system draws 50 µW.

0.16

0.23

IL as function of time

leakage after 120 sec: IL,0 = 2 µA

0.3

leakage at long time: IL,0 ~ 0.2 µA

10V rated voltage: IL ~ 0.16 IL,0

0.03Long-term leakage current: ILoss = 32 nALong-term leakage power: PLoss = 72 nW


120 s

RechargeableRechargeable lithiumlithium batteriesbatteries

Advantages of the lithium systemno memory effectno memory effectaccepts charge and discharge current in all states (discharged, partially charged)reasonable cell voltage (~ 3V)acceptable self-discharge rate (~ 10%/month)prolonged operational lifetime, if not fully charged/dischargedhigh energy densityhigh energy densitysmall size and weightlow toxicity

Disadvantagesreduced lifetime, when operated at elevated temperaturesreduced capacity at low temperatures (like all batteries)limited acceptance of trickle chargeRequires a more sophisticated charge management


Requires a more sophisticated charge management

RechargeableRechargeable Lithium Lithium microbatteriesmicrobatteries

Typical Characteristics

Example: Seiko MS 920 SE 3V/11mAhExample: Seiko MS 920 SE 3V/11mAh

Nominal voltage 3.0 VCharge voltage range 2 8 3 3 VCharge voltage range 2.8 … 3.3 VStandard charge voltage 3.1 VNominal capacity C 11 mAh

Ø 9,5 mm x 2,8 mm,weight 0,47 g

Standard charge conditions max. 0.2 mA @ 3.1 Vfor 72 hrs

Standard discharge current 50 µAStop of discharge at 2.0 VCycle life (No. of cycles)

100% discharge per cycle10% discharge per cycle

1001000


RechargeableRechargeable Lithium Lithium microbatteriesmicrobatteries

Brown-out capabilities (Seiko MS 920 SE)

Assumption: Our low power sensor systemAssumption: Our low-power sensor system runs on 50 µW at 2.3 V (minimum).

W50 V32 2.3 V

2.7 V

µAV

µWIL 223.2

50== Ω==⇒ k

µAVRL 105

223,2 2.3 V

Discharge from 100% to 90% only 10 mAh

AhCVUlVUvoltagestart start

11921,3:

⎪⎬

⎫=

1,1 mAh

hRCT 4010mAhCVUvoltageendVUvoltageaver

stop

aver 1,17,2:9,2:. 10 =⇒

⎪⎭

⎪⎬

== hrsR

UCT L

aver

401010 =⋅=

B lif i 1 000 l 40 h 40 000 h 4 5Battery lifetime: 1.000 cycles x 40 hrs = 40.000 hrs = 4.5 years

„Keep your battery large enough and full enough“


„ p y y g g g

A concept for hydrogenA concept for hydrogen--based energy storagebased energy storage

6 mm6 mm

19 mm19 mm

chip-integratedfuel cell with Pd storage

6 mm

storage

[V]

[mW

/cm

²]

volta

ge [

wer

den

sity

[

0 5 mm thick fuel cell:

current density [mA/cm²]

pow 0.5 mm thick fuel cell:

photograph (right) andits electrical characteristics


G. Erdler, M. Frank, M. Lehmann, H. Reinecke, C. Mueller, Sensors & Actuators A 132/1 (2006), 331-336.

Thermal Thermal batteriesbatteries ??

Thermal heat capacity and energy of materials

Material Heat capacityCV [MJ/(m³K)]

Thermal energy(V =10 cm³ ,ΔT = 10 K)

Electricalenergy Wel

Operational time at 50 µW power consumption

aluminium 2,45 68 mWh 340 µWh 6,8 hrscopper 3,43 95 mWh 475 µWh 9,5 hrsmagnesium 1,78 49 mWh 245 mWh 4,9 hrsg , ,motor oil 1,65 46 mWh 230 µWh 4,6 hrssilicone oil 1,42 39 mWh 195 µWh 3,9 hrs

t 4 17 115 Wh 575 Wh 11 5 h

Energy extraction (e.g. with a thermoelectric generator)

water 4,17 115mWh 575 µWh 11,5 hrs

TCVWefficiencyconversion

KTdifferenceetemperaturVel Δ⋅⋅⋅=⇒

⎭⎬⎫

==Δ

ηη %5,0:

10:


„Wise“ „Wise“ operationoperation („(„WhyWhy doesdoes thethe bearbear knowknow whenwhen toto sleepsleep?“)?“)

ActivityBioinspired control strategies

learning operating systemslearning operating systemsprognosis toolsenergy-optimized algorithms

Metabolism

internal Clocks …Energy reserve

energy consumption = f1(A,M,T,D,…)available prey = f2(T,D,S...)E = f (energy consumption prey )E = f3(energy consumption, prey,..)…„I have learned that …“I know that “Light intensity „I know that …

TemperatureDay lengthSeason

Weather…

Light intensity


Cartoon: „The bear that couldn‘t sleep“, 1939, © MGM

„Wise“ „Wise“ operationoperation („(„WhyWhy doesdoes thethe systemsystem knowknow whenwhen toto sleepsleep?“)?“)

Bioinspired control strategieslearning operating systemslearning operating systemsprognosis toolsenergy-optimized algorithms


J. Hsu, UCLA, 2005

Demonstrator: Remote Demonstrator: Remote TemperatureTemperature MonitoringMonitoring

Application szenario:35 4 °C

tRF

transmitter

Remote temperaturesensing at „heavy“

hi

Energy-autonomous

35,4 CRF

receiversensor system

Micro-

transmitter machinery …

35 4 °C

receiver

Temperature

Micro-controller Temperature ?

35,4 °C

Temperature sensorEnergy management

and storage

VibrationPiezogenerator


g

System System setset--upup

RequirementsRequirementswell-defined turn-on and turn-offlow-voltage operationg plow-power operation

P Woias M Wischke C Eichhorn B Fuchs


P. Woias, M. Wischke, C. Eichhorn, B. Fuchs, Proc. PowerMEMS 2009, Washington, DC, USA, 209-212

StackedStacked impactimpact--type type piezogeneratorpiezogenerator

impact type non-resonant

Technical datamaximum output power: 120 µWmaximum output power: 120 µWoptimal output voltage: 2,15 Vtolerance band: ± 0,2 Vbeam type


resonant

MicroMicro EnergyEnergy ManagementManagement

What we do …storage

typical CMOS load curve

0,4

0

U0 = 0.5 UDDU0 = 1.0 UDDU0 = 1.5 UDDoperationalstorage

0,2

0,3

pow

er P

L/P0

turn onoff state

generator load

generatorpowercurve

0,1

,

rmal

ized

p

and what could be done :

curve0

0 0,2 0,4 0,6 0,8 1

no

normalized voltage UL/U0

(active) rectificationi d t h

start-up controlpo er do n control

… and what could be done :

impedance match voltage transformationgenerator control

power-down control voltage transformationimpedance match


DefinedDefined „„wakewake--upup“: “: WhyWhy not not buybuy … ?… ?

Problems with today‘s ICsno „real low voltage“

d fi d b th h ldundefined sub-threshold behaviourlimited functionality (not

f f )


specific for energy harvesting)

LowLow--voltagevoltage linear linear regulatorregulator withwith sharp turnsharp turn--onon

1938Otto Schmitt


LowLow--voltagevoltage linear linear regulatorregulator withwith sharp turnsharp turn--onon

30

Characteristics20

30

ptio

n [µ

W]

Characteristicssafe-operation supply voltage: 0.4 V ☺max. power consumption: 25 µW

10

wer

con

sum

p

optimization potential: 1…3 µW ☺novel design (pat. pend.): < 1 µW ☺ ☺

00 0,5 1 1,5 2 2,5

Pow

Supply voltage [V]


System System operationoperation

P Woias M Wischke C Eichhorn B Fuchs


P. Woias, M. Wischke, C. Eichhorn, B. Fuchs, Proc. PowerMEMS 2009, Washington, DC, USA, 209-212

ConclusionsConclusions

Energy Harvesting is at the end of its „first decade of today‘s research“.

Many (most?) basic principles of energy harvesting are explored.

Research becomes and has to be more driven by applicationsResearch becomes - and has to be - more driven by applications.

The up-coming challenges are similar to those of biological systems:

adaptivity

efficient energy storage

wise system operation

Our task is to design energy-autonomous embedded systems. E h ti l ill t l th blEnergy harvesting alone will not solve the problem.

…however, we will need and use this technology, definitely.


Thank you very much for your attention !for your attention !

www.imtek.dewww micro-energy-harvesting de


www.micro-energy-harvesting.de

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