Piezo Electricity

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Abstract:

The energy crisis has become a major problem in the 21st century. To meet thedemands we have to Increase the generation of electrical energy. This is not possible by

using the non renewable energy sources that are available because their utilization

makes them not available for the future use more over their increase in utilization causesto increase the installation and running charges also increases the cost of energy per unit.

Hence we have chosen the alternative, the cheap and best sources they are renewable

energy generation sources like piezoelectricity

This paper aims at introducing a piezoelectric energy sources device which converts

mechanical vibrations into electrical energy. It explains the essential features of thedevice and tries to convey the key design and various construction details. Its reliability,

compactness and survivability under harsh conditions make it the future of powergeneration.

Introduction:

The word "piezoelectricity" comes for the Greek word piezin, this means "to press". This term

was chosen because of the quartz's properties which allow it to generate electricity by pressure as

well as mechanical distortion under voltage. some of the pizeo materials are Quartz,

Rochelle salt, and certain ceramics.The piezoelectric effect describes the

relation between a mechanical stress and an electrical voltage in solids.

In materials having piezoelectric properties; ions can be moved

along the crystal axes easier than others. Applying pressure to the material in

certain directions result in a displacement of ions. This result in the opposite

faces of the crystal assume opposite charges. When pressure is released, the

ions return to original positions.


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Structure of piezoelectric material

How piezomaterial generates electricity ?

1. Normally, the charges in a piezoelectric crystal are exactly balanced, even ifthey're not symmetrically arranged.

2. The effects of the charges exactly cancel out, leaving no net charge on the crystal

faces. (More specifically, the electric dipole momentsvector lines separatingopposite chargesexactly cancel one another out.)

3. If you squeeze the crystal (massively exaggerated in this picture!), you force thecharges out of balance.


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4. Now the effects of the charges (their dipole moments) no longer cancel one

another out and net positive and negative charges appear on opposite crystalfaces. By squeezing the crystal, you've produced a voltage across its opposite

facesand that's piezoelectricity!


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Piezoelectricity

A related property known as pyroelectricity, the ability of certain mineral

crystals to generate electrical charge when heated, was known of as early asthe 19th century, and was named by David Brewster in 1824. In 1880, the

brothers Pierre Curie and Jacques Curie predicted and demonstrated

piezoelectricity using tinfoil, glue, wire, magnets, and a jeweler's saw. They

showed that crystals of tourmaline, quartz, topaz, cane sugar, and Rochelle

salt (sodium potassium tartrate tetrahydrate) generate electrical polarization

from mechanical stress. Quartz and Rochelle salt exhibited the most

piezoelectricity.


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Converse piezoelectricity was mathematically deduced from fundamental

thermodynamic principles by Lippmann in 1881. The Curies immediately

confirmed the existence of the "converse effect," and went on to obtain

quantitative proof of the complete reversibility of electro-elasto-mechanicaldeformations in piezoelectric crystals.

The first practical application for piezoelectric devices was sonar, first

developed during World War I. In France in 1917, Paul Langevin (whose

development now bears his name) and his coworkers developed an ultrasonic

submarine detector. The detector consisted of a transducer, made of thin

quartz crystals carefully glued between two steel plates, and a hydrophone to

detect the returned echo. By emitting a high-frequency chirp from the

transducer, and measuring the amount of time it takes to hear an echo from

the sound waves bouncing off an object, one can calculate the distance to

that object.

The use of piezoelectricity in sonar, and the success of that project, created

intense development interest in piezoelectric devices. Over the next few

decades, new piezoelectric materials and new applications for those

materials were explored and developed.

Development of piezoelectric devices and materials in the United States was

kept within the companies doing the development, mostly due to the wartime

beginnings of the field, and in the interests of securing profitable patents.

New materials were the first to be developed quartz crystals were the first

commercially exploited piezoelectric material, but scientists searched for

higher-performance materials.

Piezoelectric devices found homes in many fields. Ceramic phonograph

cartridges simplified player design, were cheap and accurate, and maderecord players cheaper to maintain and easier to build. Ceramic electret

microphones could be made small and sensitive. The development of the

ultrasonic transducer allowed for easy measurement of viscosity and

elasticity in fluids and solids, resulting in huge advances in materials

research. Ultrasonic time-domain reflectometers (which send an ultrasonic

pulse through a material and measure reflections from discontinuities) could

find flaws inside cast metal and stone objects, improving structural safety.


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However, despite the advances in materials and the maturation of

manufacturing processes, the United States market had not grown as quickly.

Without many new applications, the growth of the United States' piezoelectric

industry suffered.

In contrast, Japanese manufacturers shared their information, quickly

overcoming technical and manufacturing challenges and creating new

markets. Japanese efforts in materials research created piezoceramic

materials competitive to the U.S. materials, but free of expensive patent

restrictions. Major Japanese piezoelectric developments include new designs

of piezoceramic filters, used in radios and televisions, piezo buzzers and

audio transducers that could be connected directly into electronic circuits,

and the piezoelectric igniter which generates sparks for small engine ignition

systems (and gas-grill lighters) by compressing a ceramic disc. Ultrasonic

transducers that could transmit sound waves through air had existed forquite some time, but first saw major commercial use in early television

remote controls. These transducers now are mounted on several car models

as an echolocation device, helping the driver determine the distance from the

rear of the car to any objects that may be in its path.

Power generating from waking floor:

In order for the energy from walking motion tobe captured, piezoelectric devices must beinstalled underneath the floor in terminal


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buildings.Placing piezoelectric devices that areused to capture energy from foot trafficunderneath terminals can effectively captureelectrical energy and send it back to the powergrid through inverters, which are needed in order

to convert the DC power, from the piezoelectric,into AC power used by terminal lighting systems(Inverters for solar panel installations work justas well for piezoelectric devices). Quartz,Rochelle salt, and certain ceramics all exhibitpiezoelectric behaviors.

Shoes striking a piezoelectric pad underneath afloor tile act like a hammer hitting the crystalmaterial inside the pad. This energy from theshoe then creates a voltage that can be used to

power lighting systems. Hundreds or eventhousands of these piezoelectric devices wouldbe installed underneath flooring to capture thekinetic energy from walking

Power

generating on floors.

Tokyo Train Station and how it generateselectricity through piezoelectric installed atthe ticket area,(Courtesy Japan RailwaysGroup).


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The East Japan Railway Company (JR East)

conducted a demonstration experiment from January 19

to March 7, 2008, at Yaesu North Gate, Tokyo Station, on

a new power-generating floor. Installed at the ticket gate

area, it generates electricity from the vibrations created

by passengers walking through the ticket gates.

Power generating on Highway:

Piezoelectric devices installed on highways to harvest

energy from passing vehicles. By sitting there andgetting run over by motorcars, that is. In an

effort to best other power-generating highwayoptions that involve solar panels and enlargedblender arms, Britain's Environmental TransportAssociation is looking to test a prototypehighway that's embedded with piezoelectriccrystals. Essentially, the process would workmuch like the power-generating Tokyo stationfloors we saw earlier this week; each car thatsquishes a crystal would contribute a tiny bit ofenergy, and the collective effect could beenormous. In fact, it's estimated that a single

kilometer of roadway could generate 400-kilowatts of energy, or enough to power aroundeight small cars.

Researchers at the Techion-Israel Institute ofTechnology in Haifa hope to convert open highwaysinto renewable energy generators using thetechnology that has always made some heads turn piezoelectricity. Developed by Haim Abramovich, theplan intends to place piezoelectric crystals under the

asphalt that convert vibrations of passing vehiclesinto electricity

Piezoelectricity in Daily Life:

Piezoelectricity actually is as common as backyard grills.

Push-button grill starters, and likewise pushbutton cigarette

lighters, both use piezoelectric materials to strike a spark.


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Microphones and quartz watches are two other common

products that use the piezoelectric effect. Piezoelectricity

also has numerous medical and engineering applications,especially in ultrasound equipment and testing devices for

roads and bridges.


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Applications:


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Piezo sensor Piezo microphone Gas

lighter

High voltage and power sources

Direct piezoelectricity of some substances like quartz,

as mentioned above, can generate potential differences

of thousands of volts.

The main applications are pollution free

The best-known application is the electriccigarette lighter pressing the button causes aspring-loaded hammer to hit a piezoelectriccrystal, producing a sufficiently high voltageelectric current that flows across a smallspark gap, thus heating and igniting the gas.The portable sparkers used to light gas grillsor stoves work the same way, and many typesof gas burners now have built-in piezo-basedignition systems.

The best-known application of piezo

crystals are 1. Direct piezoelectricity of some substances like

quartz, as mentioned above, can generate potentialdifferences of thousands of volts

2. As sensing elements Detection of pressure variations in the form of sound

is the most common sensor application, e.g.


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piezoelectric microphones. Sound waves bend the

piezoelectric material, creating a changing voltage

3. Ultrasound imaging

Piezoelectric sensors are used with high frequency

sound in ultrasonic transducers for medical imaging

.For many sensing techniques, the sensor can act asboth a sensor and an actuator. Ultrasonic transducers,

for example, can inject ultrasound waves into the

body, receive the returned wave, and convert it to anelectrical signal (a voltage).

4. Sonar sensors

Piezoelectric elements are also used in the detection

and generation of sonar waves. Applications includepower monitoring in high power applications such as

medical treatment, sonochemistry and industrial

processing etc.

5. As chemical and biological sensors Piezoelectric microbalances are used as very sensitive

chemical and biological sensors. Piezo are also usedas strain gauges.

6. In Music instruments

Piezoelectric transducers are used in electronic drumpads to detect the impact of the drummers sticks.

7. Automotive application

Automotive engine management systems use a

piezoelectric transducer to detect detonation by

sampling the vibrations of the engine block.Ultrasonic piezo sensors are used in the detection of

acoustic emissions in acoustic emission testing.

8. Piezoresistive silicon devices

The Piezoresistive effect of semiconductors has been

used for sensor devices employing all kinds of

semiconductor materials such as germanium,

polycrystalline silicon, amorphous silicon, and singlecrystal silicon. Since silicon is today the material of

choice for integrated digital and analog circuits the

use of Piezoresistive silicon devices has been of greatinterest. It enables the easy integration of stress

sensors with Bipolar and CMOS circuits.

9. Piezoresistors

Piezoresistors are resistors made from a Piezoresistive

material and are usually used for measurement of

mechanical stress. They are the simplest form of

Piezoresistive device.


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ADVANTAGES:

Extremely wide dynamic range, almost free of noise -suitable for shock measurement as well as for

almostimperceptible vibratio

Ecofriendly

Excellent linearity over their dynamic range

Wide frequency range, high frequencies can be

measured

Compact yet highly sensitive

No moving parts - long service life

No external power required

Great variety of models available for nearly anypurpose

Easily embedded into laminated composites

Disadvantages:

Eficiency is less

Brittle due to crystalline structure

Produce small strains compared to SMA and

magnetostrictives

Cannot withstand high shear and tension can become

depolarized

High voltages, high temperatures, large stres

CONCLUSION:


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In this era of increasing energy costsand decreasing supplies of fossil fuels, emphasis

on protecting the environment and creating

sustainable forms of power have become vital, high

priority projects for modern society.

The most advanced green generation

technology. It used very low cost & broad

generation. A theoretical model on the

generation mechanisms of electricity by

piezoelectric material attached to a flexible

structure has been developed and tested

experimentally

REFERENCE:

M. Minary-Jolandan, and Min-Feng Yu, Nanotechnology 20 (2009) 085706 (6pp)

Lakes, Roderic. "Electrical Properties of Bone: A

Review". University of WisconsinMadison.http://silver.neep.wisc.edu/~lakes/BoneElectr.html.

Becker, Robert O; Marino, Andrew A (1982).. .

Pollack, S.R; Korostoff, E., Starkebaum, W. y

Lannicone, W (1979). ed. Brighton, C.T., Black, J. and
http://silver.neep.wisc.edu/~lakes/BoneElectr.htmlhttp://silver.neep.wisc.edu/~lakes/BoneElectr.htmlhttp://en.wikipedia.org/wiki/University_of_Wisconsin%E2%80%93Madisonhttp://silver.neep.wisc.edu/~lakes/BoneElectr.htmlhttp://en.wikipedia.org/wiki/University_of_Wisconsin%E2%80%93Madisonhttp://silver.neep.wisc.edu/~lakes/BoneElectr.htmlhttp://silver.neep.wisc.edu/~lakes/BoneElectr.htmlhttp://silver.neep.wisc.edu/~lakes/BoneElectr.html


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Piezo Electricity

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