2. CONTENT
HISTORY
PIEZOELECTRICITY
INTERNAL WORKING
THE PIEZOELECTRIC EFFECT
WORKING
PIEZOELECTRIC MATERIALS
PIEZOELECTRIC COUPLING COEFFICIENT
PIEZOELECTRIC TRANSDUCERS
PIEZOELECTRIC SENSOR
PIEZOELECTRIC ACTUATOR
APLLICAATIONS
3. HISTORY OF PIEZOELECTRICITY
The first scientific publication
describing the phenomenon
appeared in 1880
It was co-authored two brothers
by Pierre and Jacques Curie,
who were conducting a variety
of experiments on a range of
crystals at the time
In those experiments, they cataloged a number of
crystals, such as tourmaline, quartz, topaz, cane sugar and
Rochelle salt that displayed surface charges when they
were mechanically stressed
4. HISTORY OF PIEZOELECTRICITY
In the scientific community of that time, this observation was considered
as a significant discovery, and the term “piezoelectricity” was expressed
this effect
The word “piezein” is a Greek word which means “to press”
Piezoelectricity means electricity generated from pressure - a very logical
name
The discovery of piezoelectricity generated significant interest within the
European scientific community
Subsequently, roughly within 30 years of its discovery, and prior to World
War I, the study of piezoelectricity was viewed as a credible scientific
activity
5. PIEZOELECTRICITY
Piezoelectricity is the ability of certain crystals to produce a
voltage when subjected to mechanical stress (the substance is
squeezed or stretched)
Conversely, a mechanical deformation (the substance shrinks
or expands) is produced when an electric field is applied-
“reverse piezoelectric effect”
When an electric voltage is applied to a transducer crystal, the
crystal gets excited and is deformed
Examples --- Quartz, Barium titanate, tourmaline
6. INTERNAL WORKING
The effect is explained by the displacement of ions in crystals
When the crystal is compressed, the ions in each unit cell are
displaced, causing the electric polarization of the unit cell
Because of the regularity of crystalline structure, these
effects accumulate, causing the appearance of an electric
potential difference between certain faces of the crystal
When an external electric field is applied to the crystal, the
ions in each unit cell are displaced by electrostatic forces,
resulting in the mechanical deformation of the whole crystal
7. THE PIEZOELECTRIC EFFECT
Crystal
Current Meter
= zero
+ - + - + -
+ - + - + -
Charges cancel
each other, so
no current flow
Crystal material is at rest: No forces applied,
so net current flow is zero
8. THE PIEZOELECTRIC EFFECT
Crystal
Current Meter
deflects in +
direction
- - - - -
+ + + + +
Due to properties of symmetry,
charges are net + on one side &
net - on the opposite side: crystal gets
thinner and longer
Crystal material with forces applied
in direction of arrows………..
Force
9. THE PIEZOELECTRIC EFFECT
Crystal
Current Meter
deflects in -
direction
+ + + +
- - - - -
…. Changes the direction of
current flow, and the crystal gets
shorter and fatter.
Changing the direction of the
applied force………..
Force
12. WORKING
The 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
13. WORKING
Fig: (a) Random orientation of domains prior to poling
(b) Poling in DC Electric Field
(c) Remanent polarization after field is removed
14. PIEZOELECTRIC MATERIALS
Below Curie Temp,
Tetragonal
structure
Poling of dipoles in
single direction
allows for
piezoelectric
properties
The ‘Pb' atoms are
larger than the
‘Ti,Zr' atoms
Cubic Structure
(Cubic lattice-
above Curie Temp.
+ve & -ve charge
sites coincide-no
dipoles)
Perovskite Structure
(Tetragonal lattice-
below Curie Temp.
electric dipole)
16. PIEZOELECTRIC COUPLING COEFFICIENT
The piezoelectric coefficient k represents the ability of a PZ
material to transform electrical energy to mechanical energy and
vice versa
This transformation of energy between mechanical and electrical
domains is employed in both sensors and actuators made from
piezoelectric materials
For BaTiO3, k= 0.5
For Quartz, k= 0.1
17. Where Can We Use It
Mainly
Transducers;
Sensors;
Actuators;
The commercial application are done in ultrasonic
equipment, microphones, watches, spark lighters for
gas stoves, dance floors, any high traffic areas, etc.
18. PIEZOELECTRIC TRANSDUCERS
A transducer is a device that converts a signal in one form
of energy to another form of energy
Energy types include electrical, mechanical, electromagnetic
(including light), chemical, acoustic and thermal energy
While the term transducer commonly implies the use of a
sensor/detector, any device which converts energy can be
considered a transducer
Transducers are widely used in measuring instruments
19. PIEZOELECTRIC TRANSDUCERS
In this example, the first transducer could be a microphone, and
the second transducer could be a speaker
Transducers are used in electronic communications systems to
convert signals of various physical forms to electronic signals, and
vice versa
20. PIEZOELECTRIC SENSOR
A piezoelectric sensor is a device that uses the piezoelectric
effect, to measure changes in pressure, acceleration, strain or force
by converting them to an electrical charge
To detect sound, e.g. piezoelectric microphones and piezoelectric
pickups for electrically amplified guitars
Piezoelectric microbalances are
used as very sensitive chemical
and biological sensors
Piezos are used in electronic
drum pads to detect the impact of
the drummer's sticks.
21. PIEZOELECTRIC ACTUATOR
An actuator accepts energy and produces movement (action)
The energy supplied to an actuator might be electrical or
mechanical
An electric motor and a loudspeaker are both actuators,
converting electrical energy into motion for different purposes
Loudspeaker: Voltages are converted to mechanical movement
of a piezoelectric polymer film
22. Application
The first serious application for piezoelectric materials appeared during
World War I
This work is credited to Paul Langevin and his co-workers in France,
who built an ultrasonic submarine detector
The transducer they built was made of a mosaic of thin quartz crystals
that was glued between two steel plates in a way that the composite
system had a resonance frequency of 50 KHz
The device was used to transmit a high-frequency signal into the water
and to measure the depth by timing the return echo
Their invention, however, was not perfected until the end of the war
24. TRANSPORTATION INSDUSTRY
In last few years piezo electric materials have shown a
tremendous growth in the field of piezoelectric materials
25. WEAR DETECTION OF TRAIN WHEELS
This is a wear detection system for train wheels. The idea is to
detect the changes in the vibration behavior of the entire wheel
caused by the surface changes on the rolling contact area
26. HEALTH CARE INDUSTRY
It’s been said that health is wealth. Piezo-electric materials
have given this industry new wings of technology
27. POWER GENERATING SIDEWALK
Charging pads under the
cross walk collect energy
from the vibrations. Energy
generated by that
piezoelectric panels can
charge to lithium ion
batteries (which can be
used further)
28. Energy-Harvesting
Street Tiles
The special “energy harvesting
tiles” were developed by London-
based Pavegen Systems. The
power thus generated can be
used to run low-voltage
equipment such as streetlights
and vending machines.
A typical tile is made of recycled
polymer, with the top surface made
from recycled truck tires. A foot-step
that depresses a single tile by five
millimeters produces between one and
seven watts.
29. Club Watt
In 2007. Doell Architects and Enviu collaborated on a design of a floor
tile that using Piezoelectricity would light up
The floor tiles were presented in Live Earth Event 070707 for the 1st
time
Doell and Enviu set-up to design a sustainable dance club
In Sep 04, 2008, Club Watt was opened, the 1st sustainable dance
club in the world!
Watt’s Sustainable solutions
Club Watt makes substantial savings on the consumption of energy
(30%), water (50%) and CO2 (50%)
This method resulted in savings for the building and organisation
30. Club Watt
The dance floor is a fusion of
electronics, embedded software &
smart durable materials. Every tile
makes a vertical movement of up
to 1 cm when danced on. These
movements are transformed by an
advanced electric motor into
electric power. Every person is able
to produce 2-20 Watt, depending
on the dancers’ weight and activity
of dance floor. The generated
energy is then used to power the
interactive elements of the floor or
can be used to power other
systems. The technology of the
dance floor is continuously being
developed.
The dance floor produces 10% of the
total club energy
The technology of the floor can also
be used for other applications such as
gyms, railway, stations & any other
areas with high traffic
31. FLOOR MATS
Series 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.
When mob uses the dance
floor, an enormous voltage
is generated.
This energy is used to power
the equipment of nightclubs.
Simultaneously
the lights, on
the wall, blink
32. ENERGY-HARVESTING STREET TILES
These tiles generate electricity
with a hybrid solution of
mechanisms that include the
piezoelectric effect (an electric
charge produced when pressure is
exerted on crystals such as quartz)
and induction, which uses copper
coils and magnets
The marathon runners generated
4.7 kilowatt-hours of energy,
enough to power a five-watt LED
bulb for 940 hours, or 40 days
In Paris, on April 7, 2013, Kenya’s Peter Some won the 37th Paris
Marathon with a time of 2:05:38, but around 37,000 runners were
all involved in a part of a historic event. As they ran across the
Avenue des Champs Élysées and thumped their feet on such 176
special tiles laid on a 25-meter stretch, the athletes generated
electricity
33. GYMS AND WORKPLACES
Vibrations 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.
34. MOBILE KEYPAD AND KEYBOARD
Crystals laid down under
keys of mobile unit and
keyboard.
For every key pressed
vibrations are created.
These vibrations can be
used for charging
purposes.
35. POWER GENERATING BOOTS AND SHOES
Idea was researched by
DARPA in US
To power the battlefield
equipment by generators
embedded in soldier
boots
Idea was abandoned due
to the discomfort
36. 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 tranformers:
A piezoelectric transformer is a type of AC voltage multiplier.
Unlike a conventional transformer, which uses magnetic coupling
between input and output, the piezoelectric transformer uses acoustic
coupling. An input voltage is applied across a short length of a bar of
piezoceramic material such as PZT, creating an alternating stress in the
bar by the inverse piezoelectric effect and causing the whole bar to
vibrate. The vibration frequency is typically in the 100 kilohertz to 1
megahertz range. A higher output voltage is then generated across
another section of the bar by the piezoelectric effect
37. ADVANTAGES DISADVANTAGES
Unaffected by external
electromagnetic fields
Piezoelectric ceramic can be
depolarized by a strong electric
field with polarity opposite to the
original poling voltage
Pollution Free High mechanical stress can
depolarize a piezoelectric ceramic
Low Maintenance Crystal is prone to crack if
overstressed
Easy replacement of
equipment
May get affected by long use at
high temperatures
38. CONCLUSIONS
Piezoelectricity 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
