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Study

of

Piezoelectric

Devices

for

ConversionofSoundtoElectricity

B JamieSueRankinUniversityofUtah

April20th,2011

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Background:

ThermoacousticEngines

Sourceofheat

Acousticresonator

Stackof

plates

Heatexchangeratendofeachstack

Workinggas:air

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PressureSensitiveCrystals

or

Ceramics

Shapeisdistorted,itgivesoffchargewhichcreatesvoltage

Canwork

two

ways:

loudspeakerormicrophone

WideRan eofApplications

Whyusesound?

streetlights in France

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Investigation:VoltageOutputand

Frequency

Twotypes

of

crystals:

CommerciallyAvailableand.

expensivespecially

manufactured

single

crystals

voltageoutput?

Whichdeviceshaveresonant

frequencieswhich

will

fit

bestwithourheatengines?

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Loudspeaker

to20kHzaudio

Resultsinpressure

,

showsresonanteaks

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Outputssoundtobe

Broad,evenoutput;

resonance

measuredwith

makesuresoundisatthesamelevelforallpiezos

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Measuresfrequency

response

GivesACvoltage

outputof

piezoelectricdevice(RMS)

Usedto

find

the

peakoftheresonantrequency

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weepovera

frequenciesto

find

theonewhichgivesRM

t e g estvo tageoutput

SharpQ

=Extremely

Volta

ge(

narrowfrequencyband(~5Hz)

Out ut is enerall

0to50m

about

10times

largerthanoff

)

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CharacterizingPiezoelectricDevices

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VoltageResponse

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ResonantFrequencies

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InterpretationofResults

Thecommerciallyavailablepiezoelectricdevicesseem

output Surprisinglywidevariation

nt eper ormanceosinglecrystalpiezos

operatebetween2and3kHz

3kHzthermoacousticenginearethecommercial

rass an s ng e

crystal

15BUsing sound to light up LEDs