PIEZOELECTICITY AND ITSAPPLICATIONS

By:AZEEM AHMAD KHANELECTRONICS ENGG.

A4LE 44

Under the Guidance of :

Prof. MJR Khan Sb.

CONTENTS

1.INTRODUCTION2.MATERIALS3.WORKING4.APPLICATIONS5.CONCLUSION

INTRODUCTIONPiezoelectricity was discovered by Curie brothers in 1880.It is the generation of electric field from applied pressure.It is observed in crystalline materials with no inversion

symmetry.The materials exhibiting the direct piezoelectric also

exhibit the reverse piezoelectric effect (the internal generation of a mechanical strain resulting from an applied electrical field).

MATERIALSNATURAL SYNTHETIC

Quartz Lead zirconate titanate (PZT)

Rochelle Salt Zinc oxide (ZnO)

Topaz Barium titanate (BaTiO3)

Sucrose Gallium orthophosphate (GaPO4)

Tendon Potassium niobate (KNbO3)

Silk Lead titanate (PbTiO3)

Enamel Lithium tantalate (LiTaO3)

Dentin Langasite (La3Ga5SiO14)

DNA Sodium tungstate (Na2WO3)

WORKINGThe positive & negative charges are symmetrically

distributed in a crystal.

Piezoelectric ceramic materials are not piezoelectric

until the random ferroelectric domains are aligned by

a process known as POLING.

Poling consists of inducing a DC voltage across the

material.

Contd.

Fig: (a) Random orientation of domains prior to poling (b) Poling in DC Electric Field (c) Remanent polarization after field is removed

Contd. When pressure is applied to an object, a negative

charge is produced on the expanded side and a positive charge on the compressed side.

Once the pressure is relieved, electrical current flows across the material.

PIEZO TRANSDUCER

PRIME APPLICATION

PIEZOELECTRIC ENERGY HARVESTING

POWER GENERATING SIDEWALK

GYMS AND WORKPLACESVibrations caused from

machines in the gym.At workplaces,

piezoelectric crystal are laid in the chairs for storing energy.

Utilizing the vibrations in the vehicle like clutches, gears etc.

MOBILE KEYPADS & KEYBOARDSCrystals laid down under

keys of mobile unit and keyboard.

For every key pressed vibrations are created.

These vibrations can be used for charging purposes.

POWER GENERATING BOOTS OR SHOESIdea was researched in

US.To power the battlefield

equipment by generators embedded in soldier boots.

Idea was abandoned due to the discomfort.

FLOOR MATS AND PEOPLE POWERED DANCE CLUBSSeries of crystals can be laid below the floor mats, tiles

and carpets.One footstep can only provide enough electrical current

to light two 60-watt bulbs for one second. [source: Christian Science Monitor].When mob uses the dance floor, an enormous voltage is

generated.This energy is used to power the equipment of

nightclubs.

OUTPUT POWERThe output voltage obtained from a single

piezoelectric crystal is in millivolt(mV) range, which is different for different crystals.

And the wattage is in microwatt(µW) range. In order to achieve higher voltages, the piezoelectric

crystals can be arranged in series.Used to charge batteries for backup supplies or to

power low-power microprocessors.

OTHER APPLICATIONS:Electric cigarette lighter: Pressing the button of the lighter causes a spring-loaded hammer to hit a piezoelectric crystal, producing a sufficiently high voltage that electric current flows across a small spark gap, thus heating and igniting the gas.

As sensing elements: Detection of pressure variations in the form of sound is the most common sensor application, e.g. piezoelectric microphones. Sound waves bend the piezoelectric material, creating a changing voltage.

ADVANTAGES DISADVANTAGESUnaffected by external electromagnetic fields.

They cannot be used for truly static measurements

Pollution FreeCan pick up stray voltages in connecting wires.

Low Maintenance Crystal is prone to crack if overstressed.

Easy replacement of equipment.

May get affected by long use at high temperatures.

CONCLUSIONPiezoelectricity is a revolutionary source for “GREEN

ENERGY”. Flexible piezoelectric materials are attractive for power

harvesting applications because of their ability to withstand large amounts of strain.

Convert the ambient vibration energy surrounding them into electrical energy.

Electrical energy can then be used to power other devices or stored for later use.

REFERENCES:“Piezoelectric Electric based energy harvesting” Nuthan

Raju, V. Karthik ,T.P Mohd Jaffar Ahmed Khan.Tomasz G. Zielinski, “ Fundamentals of piezoelectricity”,

Institute Of Fundamental Technological Research, Warsaw, Poland.

Tanvi Dikshit, Dhawal Shrivastava, (February 25,2010), “ Energy Harvesting via Piezoelectricity”.

http://www.electroschematics.com/4301/piezoelectricity-design-notes.

(http://web.archive.org/web/20101006002651/http://www.eetimes.com/electronics-news/4197064/Piezoelectric-Technology-A-Primer)

http://www.instrumentationtoday.com/piezoelectric-transducer/2011/07/

THANK

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