Eelectric Energy Harvesting Through Piezoelectric Polymers Formal Design Review Don Jenket, II Kathy...

EelectricEnergy Harvesting

Through Piezoelectric Polymers

Formal Design Review

Don Jenket, II

Kathy Li

Peter Stone

March 11, 2004 Eelectric Formal Design Review

Presentation Overview

Project Goals

Choice of Materials

Choice of Processing Techniques

Device Architecture

Future Tests

Revised Timeline


Objective

DARPA Objective: Convert mechanical energy from a fluid medium into electrical energy. Fluid flow creates oscillations in an eel body Creates strain energy that is converted to AC

electrical output by piezoelectric polymers AC output is stored and/or utilized

3.082 Objective: Harness enough power from air flow to operate a L.E.D.


PVDF- Poly(vinylidene fluoride)

CC

H

H

F

F n

PropertiesChemically InertFlexibleHigh Mechanical Strength

ProductionReact HF and methylchloroform in a refrigerant gasPolymerization from emulsion or suspension by free radical vinyl polymerization

References: http://www.psrc.usm.edu/macrog/pvdf.htm, Accessed on: 3-9-04; Piezoelectric SOLEF PVDF Films. K-Tech Corp., 1993.


Piezoelectric PVDFMolecular Origin Fluorine atoms draw electronic density away from carbon and

towards themselves Leads to strong dipoles in C-F bonds

Piezoelectric Model of PVDF (Davis 1978) Piezoelectric activity based upon dipole orientation within

crystalline phase of polymer Need a polar crystal form for permanent polarization

Reference: Davis, G.T., Mckinney, J.E., Broadhurst, M.G., Roth, S.C. Electric-filed-induced phase changes in poly(vinylidene fluoride). Journal of Applied Physics 49(10), October, 1978.

-phase (piezoelectric)

-phase (anti-parallel dipoles)


Piezoelectric PVDFPoled by the Bauer Process Biaxially stretch film: Orients some crystallites with their polar axis

normal to the film Application of a strong electric field across the thickness of the film

coordinates polarity Produces high volume fractions of -phase crystallites uniformly

throughout the poled material

Electromechanic coupling factor 0.11

Young’s Modulus ~2,500 MPa

Melting Point 175º C

Depoling Temperature 90º C

Selected Properties of 40 m thick bioriented PVDF

Table courtesy of K-Tech CorporationReference: Piezoelectric SOLEF PVDF Films. K-Tech Corp., 1993.


Tensile Testing of PVDFCross-sectional Area of the Film Tested: 1 cm X 40 microns = 4 X 10-7 m2

Measured strain: .063Force at .063 strain: 3.95 lbs.

Elastic Modulus Calculated: 2.56 GPa

E = -1

Clamp

Rubber

PVDF


Electrodes and WiresDesired Properties Electrodes

High Conductivity Flexibility Won’t oxidize

Wires Ease of Attachment Flexibility

The Process Attach Electrodes using RF Magnetron Sputtering Sputter 40 nm thick Gold electrodes on sample Attach 3 mil copper wire with silver paste


Schematic of Sputtering

Vacuum Pump

Vacuum Pump

Main Chamber

Load-Lock Chamber

Sample Holder; Sample faces down

Sample Holder Rotates

Sputter Guns

Load-Lock Arm

Adapted From: Twisselmann, Douglas J. The Origins of Substrate-Topography-Induced Magnetic Anisotropy in Sputered Cobalt Alloy Films . MIT Doctoral Thesis, February, 2001


Sputtering Apparatus

Load-Lock Chamber

Vacuum Pump Main Chamber

Sample Holder


Sputtering Target


“Eel Tail” Schematic

Top View

Side View Front View

Cu Wire

6-10 cm

2 cm

6-10 cm 2 cm

0.04 mm

Cu Wire

Silver paste

Gold Electrode


Air Flow Testing of Eel TailFor cost purposes, used unpoled PVDFThickness of PVDF film: 74 m.Can visually inspect eel oscillations Wave forms Estimate flexure and strain

Tested 2 cm by {5,6,7,8,9,10} cm tails

Fan PVDF

Copper “Fin”

Length= 5-10 cm

2 cm


Air Flow Testing of Eel Tail

2cm x 6cm PVDF


Air Flow Testing of Eel Tail

2cm x 10cm PVDF


Piezoelectric Response in Air Flow

2cm x 6cm Piezoelectric PVDF


Estimation of Piezoelectric Response

V = 3/8 * (t/L)2 * h31 * z,

t= thickness; L = Length; z = bending radius and

h31 = g31*(c11 + c12)+ g33*c13

g31 = 6*10-12/11o [V*m/N] c11 = 3.7 GN*m-2 L = 6 cm

g33 = -0.14 [V*m/N] c12 = 1.47 GN*m-2 t = 40 m

z = 3 cm c13 = 1.23 GN*m-2

Equation taken from: Herbert, J.M., Moulson, A.J. Electroceramics: Materials, Properties, Applications. Chapman and Hall: London, 1990.

Piezoelectric Constants taken from: Roh, Y. et al. Characterization of All the Electic, Dielectric and Piezoelectric Constants of uniaxially oriented poled PVDF films. IEEE Transactions on Ultrasonics, Ferroelectics and Frequency Control. 49(6) June 2002.

If we model the tail as a cantilever:


Estimation of Piezoelectric Response

Estimated voltage: 0.7322 VVoltage Measured in Air Field: 0.207 VVoltage required to bias Ge-doped diode: 0.2 VSources of Error in EstimationCantilever does not account for oscillationWave form of eel is not a cantilever; looks

more like a sinusoid.


Rectifier Design

ACin

Reference: http://www.mcitransformer.com/i_notes.html


Proposed Integrated Design

Fan

RectifierStorage Circuit

Electronics Housing


Future ResearchDynamic Mechanical Testing (DMA) - ?OscilloscopeQuantified wave forms (peak amplitude)Frequency

Continued Air Stream TestingPossible water system (time permitting)Environmental Protection stiffens the eelUnderstanding vortex shedding


Project Timeline

2/10 2/17 2/24 3/2 3/9 3/16 4/1 4/6 4/13 4/20 4/27 5/4 5/11Electroded piezoelectronic sampleObtain PVDFInvestigate electrode technologyAttach electrodes to PVDFPreliminary measurementsBuild PrototypeElectronic CircuitryEnvironmental ProtectionConstruct Housing/BarrierTest PrototypeAir testingOutput measurementOptimizing PrototypeBuild Prototype IIOptimizing CircuitryTest protoype IIInvestigate water (time permitting)Prepare DemoFinal Presentation

Eelectric Energy Harvesting Through Piezoelectric Polymers Formal Design Review Don Jenket, II Kathy...

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