Applications of piezo-electricity

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APPLICATIONSOF

PIEZOELECTRICITY

By- Sakti Prasanna Muduli

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OVERVIEW1) Introduction2) Cause of piezoelectricity3) Discovery4) Materials exhibiting this property5) Field of applications6) Mechanism of some applications7) Conclusion

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WHAT THE PIEZOELECTRICITY IS

Piezoelectric Effect is the ability of certain materials to generate an electric charge in response to applied mechanical stress.

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Reverse piezoelectric effect: when voltage is applied on two

opposite surfaces of a piezoelectric material that shows expansion or contraction.

Piezoelectricity is derived from the

Greek word “piezo” or “piezein” which means to squeeze or press.

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CAUSE OF PIEZOELECTRICITY

Piezoelectric effect is formed in crystal having no centre of symmetry.

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DISCOVERY Piezoelectric effect was first proven

in 1880 by the French Physicist brothers Pierre and Jacques Curie

Pierre Curie Jacques Curie

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MATERIALS EXHIBITING THE PROPERTY:NATURAL OCCURING MATERIALS:

1) Quartz(SiO2)2) Sucrose (table sugar)3) Rochelle salt4) Topaz(Al2SiO4(F,OH)2)5) Dry bone6) DentineSYNTHETIC MATERIALS:7) Barium titanate (BaTiO3)8) Lead zirconate titanate9) Potassium niobate (KNbO3)10) Bismuth ferrite (BiFeO3)11) Sodium niobate (NaNbO3)

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APPLICATION FIELDSA. As high voltage power source: LPG stove Lighter and Cigarette lighter Energy harvesting in micro scale (New concept) Piezoelectric transformer (New concept)B. Sensors and Actuators: High precision piezoelectric microphones Electric guitar pickup Piezoelectric micro balance (very sensitive

chemical and biological sensors) Strain gauge Electronic drum pad Pressure sensors Accelerometer (New concept) Loud speaker and buzzer(Actuator)

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C. As frequency standard: General quartz clock Crystal oscillatorD. Sonic and Ultra sonic applications Underwater submarine detection Ultrasound in medical technology Metal fault detection

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E. Piezoelectric motor: A piezoelectric motor or piezo motor is

a type of electric motor based upon the change in shape of a piezoelectric material when an electric field is applied.

Piezoelectric motors make use of the converse piezoelectric effect whereby the material produces acoustic or ultrasonic vibrations in order to produce a linear or rotary motion due to friction.

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Mechanism of piezo-motor:

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Uses of piezoelectric motor: Movement of camera lens Rotation of radar Very small scale valve control Laser movement in case of biomedical modern

operationsAdvantages: No stray field effect High resolution and high accuracy Rapid response Wide range of angular steps and angular velocitiesDisadvantages: Necessity for a high frequency power supply Large scale devices are impossible

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MECHANISM OF LPG STOVE LIGHTER

When a piezoelectric material is hammered a high voltage is generated and causes spark. Which is the basis of piezoelectric LPG lighter.

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Piezoelectric Igniter

Lead zirconate titanate(PZT)

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Cigarette Lighters:

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MECHANISM OF QUARTZ CLOCK

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Clock uses piezoelectric quartz crystal Oscillator as frequency standard for tracking the time.

Battery provides current to input microchip circuit Input microchip circuit makes quartz crystal (precisely

cut and shaped like a tuning fork) oscillate (vibrate) 32768 times per second.

Output microchip circuit detects the crystal's oscillations and turns them into regular electric pulses, one per second.

Electric pulses drive miniature electric stepping motor. This converts electrical energy into mechanical power.

Electric stepping motor turns gears. Gears sweep hands around the clock-face to keep time

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Crystal Oscillators:

Crystal oscillators are not only used in clock but in all microprocessor based digital systems

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PIEZOELECTRIC TRANSFORMER

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An ac voltage is applied to the VIN electrodes,

causing mechanical expansion and compression in the thickness direction.

This displacement on the primary is transferred as a force in the longitudinal or length direction.

Mechanical resonance occurs Due to transverse and longitudinal vibration.

Voltage gain is a function of the PZT is given by

Where g(w) is piezoelectric material co-efficient

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MECHANISM OF PIEZOELECTRIC ACCELEROMETER

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ENERGY HARVESTING USING PIEZOELECTRICITY

Vibrations can be used to generate electricity in micro scale using piezoelectric materials.

Sources of vibration: Walk sides Railway tracks Shoes or boots Mobile keypad and keyboard Floor mat, tiles and carpets

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This is the circuit for utilisation of generated energy.The generated ac voltage is rectified and stored in a capacitor for use.Also trickle charge can be provided to a battery to recharge it.

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CONCLUSION Revolutionary concept in the field of

sensors and transducers. There are also some future aspects

those need to be developed such as piezoelectric accelerometer, motor, underwater acoustic transducers, piezoelectric transformers ect.

Energy harvesting through piezoelectricity is both economical and eco-friendly.

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REFERENCESBOOKS J.P. Bentley, Principles of Measurement Systems- Pearson

Education William D. Callister, David G. Rethwisch, Material Science

and Engineering an introduction, Wiley Publication How it works, The clock, A CBT Publication K. Krishna Murty, How things work?, Pustak MahalWEB https://en.wikipedia.org/wiki/Piezoelectricity http://www.explainthatstuff.com/quartzclockwatch.html http://www.mmech.com/transformers https://en.wikipedia.org/wiki/Piezoelectric_accelerometer http://www.explainthatstuff.com/accelerometers.html https://en.wikipedia.org/wiki/Piezoelectric_motor

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