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
April 8, 2004 Eelectric Progress Report
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
April 8, 2004 Eelectric Progress Report
Piezoelectric Response in Air Flow
2cm x 10cm Piezoelectric PVDF
April 8, 2004 Eelectric Progress Report
PZT Composite Tail
http://web.media.mit.edu/~testarne/TR328/node7.html
April 8, 2004 Eelectric Progress Report
PZT Composite Response in Air Flow
PZT
April 8, 2004 Eelectric Progress Report
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:
April 8, 2004 Eelectric Progress Report
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
April 8, 2004 Eelectric Progress Report
“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
April 8, 2004 Eelectric Progress Report
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
April 8, 2004 Eelectric Progress Report
Sputtering Apparatus
Pelco SC-5, Automatic High Resolution Sputter Coater
Sample Chamber
April 8, 2004 Eelectric Progress Report
Sputtering Target
Sample Chamber
SampleSputtering Au
April 8, 2004 Eelectric Progress Report
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
April 8, 2004 Eelectric Progress Report
Future RevisionsStrain Relief of Wires
Reinforce Silver Paste with tapeOffset Polymer LayersAllows for easier weaving and/or adhesion
of wire to polymer
April 8, 2004 Eelectric Progress Report
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