Eelectric Energy Harvesting Through Piezoelectric Polymers Progress Report - April 8

EelectricEnergy Harvesting

Through Piezoelectric PolymersProgress Report - April 8

Don Jenket, IIKathy Li

Peter Stone

April 8, 2004 Eelectric Progress Report

Presentation OverviewBrief Review of ProgressQuantitative Analysis of MaterialsProcessing and Design ChangesProblems EncounteredFuture Design RevisionsRevised Timeline


ObjectiveDARPA 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 utilized3.082 Objective: Harness enough power from air flow to operate a L.E.D.

http://www.darpa.mil/dso/trans/energy/pa_opt.html


Piezoelectric Response in Air Flow

2cm x 10cm Piezoelectric PVDF


PZT Composite Tail

http://web.media.mit.edu/~testarne/TR328/node7.html


PZT Composite Response in Air Flow

PZT


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 = 0.011[V*m/N] c11 = 37 GN*m-2 L = 15 cm

g33 = 0.025 [V*m/N] c12 = 23.1 GN*m-2 t = 200 m

z = 2 mm c13 = 23.1 GN*m-2

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

If we model the tail as a cantilever:


Comparison of PredictionsPVDF PZT Composite

Voltage 0.7322 V 1.653 V

“Actual” Voltage1 0.7322 V 0.496 VSample Area 12 cm2 75 cm2

Area-Normalized Voltage

0.0610 V/cm2 0.0066 V/cm2

1: Takes into account actual area occupied by piezoelectric material. PVDF is pure so this value is 1 times the voltage. PZT covers approximately 30 percent of the composite so its voltage is multiplied by 0.3


“Eel Tail” Schematic II

Top View

Side View Front View

Cu Wire

9.5 cm

2 cm

9.5 cm 2 cm

0.04 mm

Cu Wire

Silver paste

Gold Electrode

2.5 cm 3.5 cm

Cu Wire

Gold Electrode

Head EndTail End


Processing & Design ChangesWires Old: 3 mil uninsulated copper New: 5 mil insulated magnet wire

Au electrode placement Old: 2.5 & 3.5 cm sections New: 2.5 & 5 cm sections

Au electrode sputtering Old : Ti Sputtering New Method: Au Sputtering


Sputtering Apparatus

Pelco SC-5, Automatic High Resolution Sputter Coater

Sample Chamber


Sputtering Target

Sample Chamber

SampleSputtering Au


Problems EncounteredUncontrolled WiresGenerates noise during measurementsCan lead to accidents…

DurabilitySample severely damaged immediately before

oscilloscope testingPoor adhesion between polymer layers

Silver paste weakens with time -> Sample falls apart

Loss on connectivity between wires and electrodes


Future RevisionsStrain Relief of Wires

Reinforce Silver Paste with tapeOffset Polymer LayersAllows for easier weaving and/or adhesion

of wire to polymer


Revised Timeline2/10 2/17 2/24 3/2 3/9 3/16 3/23 4/6 4/13 4/20 4/27 5/4 5/11

Electroded piezoelectronic sampleObtain PVDFInvestigate electrode technologyAttach electrodes to PVDFPreliminary measurementsBuild PrototypeElectronic CircuitryEnvironment ProtectionConstruct Housing/BarrierTest PrototypeAir testingOutput measurementOptimizing PrototypeBuild prototype IITest protoype IIIncorporating future revisionsPrepare DemoFinal Presentation

Eelectric Energy Harvesting Through Piezoelectric Polymers Progress Report - April 8

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