Date post: | 04-Apr-2018 |
Category: |
Documents |
Upload: | rikki-revs |
View: | 252 times |
Download: | 1 times |
of 16
7/29/2019 Piezo Electricity
1/16
7/29/2019 Piezo Electricity
2/16
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.
7/29/2019 Piezo Electricity
3/16
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.
7/29/2019 Piezo Electricity
4/16
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!
7/29/2019 Piezo Electricity
5/16
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.
7/29/2019 Piezo Electricity
6/16
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.
7/29/2019 Piezo Electricity
7/16
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
7/29/2019 Piezo Electricity
8/16
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).
7/29/2019 Piezo Electricity
9/16
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.
7/29/2019 Piezo Electricity
10/16
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.
7/29/2019 Piezo Electricity
11/16
Applications:
7/29/2019 Piezo Electricity
12/16
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.
7/29/2019 Piezo Electricity
13/16
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.
7/29/2019 Piezo Electricity
14/16
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:
7/29/2019 Piezo Electricity
15/16
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.html7/29/2019 Piezo Electricity
16/16