Micro Energy Harvesting Power Supply for Distributed and ... · Peter Woias, Hannover-Messe, IVAM-Workshop, 22.04.2010 Sheet 1 Micro Energy Harvesting Power Supply for Distributed

Sheet 1Peter Woias, Hannover-Messe, IVAM-Workshop, 22.04.2010

Micro Energy Harvesting

Power Supply for Distributed and Embedded Systems

Peter Woias

Albert-Ludwig-University of Freiburg

Department of Microsystems Engineering (IMTEK)

Laboratory for Design of Microsystems

Freiburg, Germany


Distributed MicroDistributed Micro--Embedded Systems (MES)Embedded Systems (MES)

wireless data link

micro-

sensor

wireless

transmitter

sensor input

micro-

controller

S TM

S TMS TM

S TM

S TM

S TMS TMS TMS TM

S TM S TM S TM

G

T

M

Sensor

Data processing

Communication

S

T

M

Gateway

S TMS TM

Fabrication and Transport

Building and Enviroment Medical

… power

supply ?

Automotive

Space, ….


Wire or battery Wire or battery …… or what ?or what ?

Sensors in redwood trees

© University of California

medical implants

© Vitatron

distributed and „embedded“ sensor

systems in greenhouses © Crossbow

tire pressure sensors

sensor

rope

battery service person

(vertigo-proof)


energy

conversion

materials

and

energy

storage

energy and

system

management

Micro Energy Harvesting: The VisionMicro Energy Harvesting: The Vision

heat,

light

movement,

other bugs,…

Energy-Autonomous Embedded Systems

„always on“

no battery recharging or exchange

no power cords

easy to install …

… at numerous application sites

energy management

micro-

sensor

wireless

transmitter

sensor input

micro-

controller

wireless data link

generator energy storage


Micro energy harvesting Micro energy harvesting –– IMTEKIMTEK‘‘s PhD programs PhD program

Fact sheet

financed by DFG and industry

3 associated members

22+1 PhD scholarhips

start: October 2006

run-time: 4.5 years (1st phase)

Associated Members Members Sponsors

Research topics

energy conversion

materials for energy harvesting

energy storage and management

system considerations


electromagnetic

field energy

Ambient energy and related conversion mechanismAmbient energy and related conversion mechanism

chemical

energy

electrical

energy

energy from

mechanical or

fluid motion

thermal

energy

piezoelectric

capacitive (electret)

inductive (P-magnet)

thermoelectric

fuel cells

electromagnetic,

capacitive,

EHD, MHD

(Carnot) cycle

optical

energy

photovoltaic

induction


Piezoelectric bending generators: Principle Piezoelectric bending generators: Principle

11,31 piezodq σ⋅=( )1131 σ⋅== dtd

d

td

qdI

Design challenges

homogeneous mechanical stress higher output power

tunable resonance frequency broader application range, more power

smart system integration cheaper, easier fabrication


Optimized vibrational piezo generator (2007)Optimized vibrational piezo generator (2007)

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

E. Just et al., Proc. GMM-Workshop

“Energieautarke Mikrosysteme”, 2006

F. Goldschmidtböing, P. Woias,

Journ. Micromech. Microeng. 18, 2008, 104013


FrequencyFrequency--tunable piezo generator (2008)tunable piezo generator (2008)

Principle

Actuation force in the „arms“ will

stiffen the resonating beam and

thus change its resonance frequency

high tuning range (22%)

loss of Q factor with

increasing force

C. Eichhorn et al., Proc. PowerMEMS 2008,

Sendai, Japan, 309-312.

force


Fabrication: PiezoFabrication: Piezo--PolymerPolymer--Composites (2003)Composites (2003)

vent

molding form

piezodisk

piezo disk cured polymer

molding form

liquidthermosettingpolymer

feed

Advantages

structure definition and piezo integration

in one single step

low-cost perspective via inject molding

extremely high design flexibility

actuators and generators in one single technology

20 mm

piezoceramic diskwith metal electrodes

electrical contact

polymer layer

mounting block

seismic mass

vibration


ImpactImpact--type piezo generator (2005)type piezo generator (2005)

Advantages

stress-homogenized hinge design

for a maximal output power

non-resonant operation

high output power

high output voltage

stacked devices for power multiplication

6 mWp @ 36N pulse (100 ms)


Electromagnetic generators: Principle and examplesElectromagnetic generators: Principle and examples

multi-resonant generator

Univ. Hongkong, 2002

P = 800 µWtd

dNU

Φ⋅−=

rotatory generator of the

Seiko KineticTM wrist watch

P = 5 µW

rotor

generator

batteryelectromechanic

quartz clockwork

Properties

AC currents from motion or induced AC fields

bad to fair voltage range (mV…V)

moderate source impedance (<10 kΩ)


Electromagnetic generator in PCB technologyElectromagnetic generator in PCB technology

multi-resonant generator

Univ. Hongkong, 2002

lid

wire-wound

coil

permanent

magnet

spacer

mechanical

resonator22 mm

Properties

output power:

330 µW @ 102 Hz and 1G

no-load voltage: 210 mV

(improved via modified coil design)

E. Bouendeu, J. Kovink,

IMTEK – Laboratory for Simulation


Thermoelectric generators (TEG): PrincipleThermoelectric generators (TEG): Principle

relevant material combinations α [µV/K]

Al / p-Poly-Si 195

Al / n-Poly-Si 110

p-Poly-Si / n-Poly-Si 190...320

p-Bi0,5Sb1,5Te3 / n-Bi0,87Sb0,13 200...420

TU ∆⋅=∆ α

2TA

Pp electric

∆⋅=

Seebeck voltage

Specific output power


3D micro3D micro--TEGTEG

Output power and no-load voltage @ 10K

measured: 1.612 µW

6 V

optimization potential: 36.3 µW

top heat conductor (gold)

bottom heat conductor

(silicon)

membrane with planar

thermocouples (Al-poly-Si)

thermal

insulator

(SU-8)

air chamber

for thermal

insulation

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

10

mm

7500 thermocouples


Bio fuel cells: Principle and applicationBio fuel cells: Principle and application

direct-oxidizing

glucose fuel cell

S. Kerzenmacher et al., Journ. Power Sources, 2008

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

Properties

output power: 2.3 … 3.3 µW /cm²

open cell voltage: 0.5 … 0.3 V

power requirement of a pacemaker: 10 µW

0,0

0,2

0,4

0,6

0,8

1,0

1,2

0 5 10

Current density in µA cm-2

Cell

po

ten

tial

in V

0,0

0,5

1,0

1,5

2,0

2,5

3,0

Po

wer

den

sit

y i

n µ

W c

m-2

pacemaker

IMTEK – Laboratory for

MEMS Applications


Photovoltaic generatorsPhotovoltaic generators

Properties

delivers DC voltages

thickness: 0.3...0.6 mm

flexible and washable

effiziency: 3%

sunlight: ≈ 3.0 mW/cm²

in-door: ≈ 0.1 mW/cm²

flexible Si thin film cell

on a polymer carrier

© Flexcell

„Pico Beacon“ with rigid

Si thin film cell on glass

© UC Berkeley


Polymer PV cellsPolymer PV cells

0.0 0.2 0.4 0.6-8

-4

0

4

Voc

=0.58 V

Jsc

=7.34 mA/cm2

FF=0.54

η=2.28%

Cu

rre

nt d

en

sity (

mA

/cm

2)

Voltage (V)

AM 1.5G irradiation

CathodeCathode

AnodeAnodeActive area

0.08 cm2

Active area

0.08 cm2

300 400 500 600 7000

10

20

30

40

50

Exte

rna

l

Qu

an

tum

Effic

ien

cy (

%)

Wavelength (nm)

Cathode Al

CdSe QDs/P3HT

PEDOT:PSS

Anode ITO substrate

Sunlight

Y. Zhou, M. Krüger, G. Urban, IMTEK,

Laboratory of Sensors and FMF

Summer 2009: Highest reported

efficiency value* based on CdSe QDs!


Energy densities of various storage conceptsEnergy densities of various storage concepts

high storage density of H2 in MH

acceptable (and improving)

efficiency of H2 fuel cells

Would a „hydrogen battery“

make sense ?

0

20

40

60

80

100

Fa

rad

ay e

ffic

ien

cy [

%]

Gold

Cap

Ni-M

H

Li-I

on

H2 fu

el c

ell

Ele

ctro

lyze

r

Gold Cap

Lead Acid

Adenosine

Triphosphate

NiMH

Li-Ion

H2 in MH (< 2%)

H2 in MH (4%)

H2 in MH

(nanopowder) Methanol

Electrolyte Cap.

1

10

100

1.000

10.000

1 10 100 1.000 10.000

energy density in [Wh/kg]

en

erg

y d

en

sit

y i

n [

Wh

/l]

hydrogen in metal hydrides (MH)

batteries

capacitors

Refs: J. Brodd et al, J. Electrochem. Soc.,

151 (3), 2004, K1-K11 and HERA

Hydrogen Storage Solutions, Germany


chip-integrated

fuel cell with Pd

storage

HydrogenHydrogen--based energy storagebased energy storage

G. Erdler, M. Frank, M. Lehmann, H. Reinecke, C. Mueller, Sensors & Actuators A 132/1

(2006), 331-336.

vo

ltag

e [

V]

current density [mA/cm²]

po

wer

den

sit

y [

mW

/cm

²]

0.5 mm thick fuel cell:

photograph (right) and

its electrical characteristics

6 mm6 mm

19 mm19 mm


Energy managementEnergy management

Requirements

start-up control

optimal impedance match between

generator, battery and load

voltage level transformation

active generator control

active rectification

supply voltage: < 1 V

power consumption: a few µW

Solutions, chips ? ….not

available today

(2004).

2163 µm

control ASIC for a capacitive

micro converter, Medinger,

Ph. D. thesis, MIT, and

Analog Devices, 1999

….eventually

coming along

(2007).

Solutions, microchips ?..... not available

today ( 2004).


Adaptive voltage converter for piezogeneratorsAdaptive voltage converter for piezogenerators

T. Hehn, Y. Manoli, IMTEK-

Laboratory of Microelectronics


sensor system

Temperatur

e sensor

Micro-

controller

Energy management

and storage

RF

transmitte

r

Application szenario:

Remote temperature

sensing at „heavy“

machinery …

Demonstrator: Remote Temperature MonitoringDemonstrator: Remote Temperature Monitoring

Vibration

Temperature ?

Energy-

autonomous

Piezogenerator

RF

receiver

35,4 °C

35,4 °C


System setSystem set--upup

Requirements

well-defined turn-on and turn-off

low-voltage operation

low-power operation


Stacked impactStacked impact--type piezogeneratortype piezogenerator

Technical data

maximum output power: 120 µW

optimal output voltage: 2.15 V

tolerance band: ± 0.2 V35 mm


Micro power managementMicro power management

A frequently used concept …

piezo-

generator storage load

(CMOS device)

… with inherent problems

overall bad efficiency

no safe start-up from zero power (danger of deadlock)

Solution: defined turn-on via power management

po

we

r d

raw

of

the

lo

ad


Why not buy Why not buy …… ??

Problems with today‘s ICs

no „real low voltage“

undefined sub-threshold

behaviour

limited functionality (not

specific for energy harvesting)


LowLow--voltage regulator with sharp turnvoltage regulator with sharp turn--onon

Characteristics

mimimum transistor count (3)

safe-operation supply voltage: 0.4 V

max. power consumption: 25 µW

optimization potential:1…3 µW


Demonstration Demonstration


Conclusions Conclusions

Embedded systems are an essential part of our current and future living.

Their power supply can not be done by batteries and power grids alone.

We will depend on Energy Harvesting.

However, its successful application will require an optimum interplay of …

energy conversion

energy storage

energy management

system hardware and operation

… i.e. a thorough and application-specific system design.


Thank you very

much for your

attention !

Micro Energy Harvesting Power Supply for Distributed and ... · Peter Woias, Hannover-Messe, IVAM-Workshop, 22.04.2010 Sheet 1 Micro Energy Harvesting Power Supply for Distributed

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