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Eelectric Energy Harvesting Through Piezoelectric Polymers Formal Design Review. Don Jenket, II Kathy Li Peter Stone. Presentation Overview. Project Goals Choice of Materials Choice of Processing Techniques Device Architecture Future Tests Revised Timeline. Objective.

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Eelectric Energy Harvesting Through Piezoelectric Polymers Formal Design Review


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eelectric energy harvesting through piezoelectric polymers formal design review

EelectricEnergy Harvesting Through Piezoelectric PolymersFormal Design Review

Don Jenket, II

Kathy Li

Peter Stone

presentation overview
Presentation Overview
  • Project Goals
  • Choice of Materials
  • Choice of Processing Techniques
  • Device Architecture
  • Future Tests
  • Revised Timeline

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objective
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.

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pvdf poly vinylidene fluoride
PVDF- Poly(vinylidene fluoride)

F

H

C

C

F

H

n

  • Properties
    • Chemically Inert
    • Flexible
    • High Mechanical Strength
  • Production
    • React HF and methylchloroform in a refrigerant gas
    • Polymerization 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.

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piezoelectric pvdf
Piezoelectric PVDF
  • Molecular 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

a-phase (anti-parallel dipoles)

b-phase (piezoelectric)

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 Physics49(10), October, 1978.

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piezoelectric pvdf1
Piezoelectric PVDF
  • Poled 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 b-phase crystallites uniformly throughout the poled material

Selected Properties of 40 mm thick bioriented PVDF

Table courtesy of K-Tech Corporation

Reference: Piezoelectric SOLEF PVDF Films. K-Tech Corp., 1993.

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tensile testing of pvdf
Tensile Testing of PVDF
  • Cross-sectional Area of the Film Tested: 1 cm X 40 microns = 4 X 10-7 m2
  • Measured strain: .063
  • Force at .063 strain: 3.95 lbs.
  • Elastic Modulus Calculated: 2.56 GPa

Clamp

Rubber

PVDF

E = se-1

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electrodes and wires
Electrodes and Wires
  • Desired 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

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schematic of sputtering
Schematic of Sputtering

Sample Holder Rotates

Sample Holder; Sample faces down

Vacuum Pump

Load-Lock Chamber

Load-Lock Arm

Vacuum Pump

Main Chamber

Sputter Guns

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

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sputtering apparatus
Sputtering Apparatus

Sample Holder

Load-Lock Chamber

Main Chamber

Vacuum Pump

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eel tail schematic
“Eel Tail” Schematic

6-10 cm

Top View

2 cm

Cu Wire

Gold Electrode

Cu Wire

0.04 mm

Silver paste

6-10 cm

2 cm

Side View

Front View

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air flow testing of eel tail
Air Flow Testing of Eel Tail
  • For cost purposes, used unpoled PVDF
  • Thickness of PVDF film: 74 mm.
  • Can visually inspect eel oscillations
    • Wave forms
    • Estimate flexure and strain
  • Tested 2 cm by {5,6,7,8,9,10} cm tails

Copper “Fin”

Fan

PVDF

2 cm

Length= 5-10 cm

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air flow testing of eel tail1
Air Flow Testing of Eel Tail
  • 2cm x 6cm PVDF

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air flow testing of eel tail2
Air Flow Testing of Eel Tail
  • 2cm x 10cm PVDF

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piezoelectric response in air flow
Piezoelectric Response in Air Flow
  • 2cm x 6cm Piezoelectric PVDF

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estimation of piezoelectric response
Estimation of Piezoelectric Response
  • If we model the tail as a cantilever:

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

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

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

g31 = 6*10-12/11eo [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 mm

dz = 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.

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estimation of piezoelectric response1
Estimation of Piezoelectric Response
  • Estimated voltage: 0.7322 V
  • Voltage Measured in Air Field: 0.207 V
  • Voltage required to bias Ge-doped diode: 0.2 V
  • Sources of Error in Estimation
    • Cantilever does not account for oscillation
    • Wave form of eel is not a cantilever; looks more like a sinusoid.

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rectifier design
Rectifier Design

ACin

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

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proposed integrated design
Proposed Integrated Design

Fan

Storage Circuit

Rectifier

Electronics Housing

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future research
Future Research
  • Dynamic Mechanical Testing (DMA) - ?
  • Oscilloscope
    • Quantified wave forms (peak amplitude)
    • Frequency
  • Continued Air Stream Testing
  • Possible water system (time permitting)
    • Environmental Protection stiffens the eel
    • Understanding vortex shedding

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