1. Piezoelectric Electric based energy
harvesting
Nuthan Raju V.
Karthik T.P
Mohd Jaffar Ahmed Khan
M.S.Ramaiah School of Advanced Studies 1

2. Contents
• Introduction
• Simple molecular model
• Energy Harvesting
• Piezoelectric Energy Harvesting
• Sources of vibration for crystal
• Applications of piezoelectricity
• Conclusion
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3. Introduction
 Piezoelectricity, discovered by Curie brothers in 1880, originated from the Greek word
“piezenin”, meaning, to press.
 The original meaning of the word “piezoelectric” implies “Pressure electricity’ –the generation of
electric field from applied pressure. This definition ignores the fact that the process is reversible,thus
allowing the generation of mechanical motion by applying a field. Piezoelectricity is observed if a
stress is applied to a solid, for example, by bending twisting or squeezing it.
 The piezoelectric effect is a special material property that exists in many single crystalline materials.
Some such crystalline structures are Quartz, Rochelle salt, Topaz, Tourmaline, Cane sugar, Berlinite
(AlPO4), bone, tendon, silk, enamel, dentin, Barium Titanate (BaTiO3), Lead Titanate (PbTiO3),
Potassium Niobate (KNbO3), Lithium Niobate (LiNbO3) etc.
 Direct piezoelectric effect – the production of electricity when stress is applied,
 Converse piezoelectric effect – the production of stress and/or strain when an electric field is
applied.
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4. Simple molecular model
 Before subjecting the material to some
external stress:
 The centres of the negative and positive charges of
each molecule coincide,
 The external effects of the charges are
reciprocally cancelled,
 As a result, an electrically neutral
molecule appears.
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5. Simple molecular model
 After exerting some pressure on the
material:
 The internal structure is deformed,
 That causes the separation of the positive and
negative centres of the molecules,
 As a result, little dipoles are generated.
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6. Simple molecular model
Eventually:
 The facing poles inside the material are mutually
cancelled,
 A distribution of a linked charge appears in the
material’s surfaces and the material is polarized,
 The polarization generates an electric field and can be
used to transform the mechanical energy of the material’s
deformation into electrical energy.
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7. Energy Harvesting
Energy harvesting describes the process of changing parasitic mechanical energy, for instance of
a vibrating structure, into electrical energy. This energy is used for other purposes. For example
driving an electrical circuit or for storage in a battery or a large capacitor.
 Energy harvesting is the process by which energy is derived from external sources and
utilized to drive the machines directly, or the energy is captured and stored for future use.
 Some traditional energy harvesting schemes are solar farms, wind farms, tidal energy
utilizing farms, geothermal energy farms and many more. With the advent of technology,
utilization of these sources has increased. When viewed on a large scale, energy harvesting
schemes can be categorized as shown in Table.
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8. Piezoelectric Energy Harvesting
 Piezoelectric Energy Harvesting comes under the category of Micro scale energy harvesting
scheme.
 The energy harvesting via. Piezoelectricity uses direct piezoelectric effect. The phenomenon
will be clear from the diagrams shown below.
Fig 1. Principle of direct piezoelectric effect
Fig 2. Structure of a piezoelectric component
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9. Piezoelectric Energy Harvesting
The output voltage obtained from a single piezoelectric crystal is in milli volt range, which
is different for different crystals. And the wattage is in microwatt range.
 In order to achieve higher voltages, the piezoelectric crystals can be arranged in series.
The energy thus obtained is stored in lithium batteries or capacitors. This is the working
principle behind piezoelectric energy harvesting system.
SOURCES OF VIBRATION FOR CRYSTAL
A. POWER GENERATING SIDEWALK
The piezoelectric crystal arrays are laid underneath
pavements, side walks and other high traffic areas
like highways, speed breakers for maximum voltage
generation. The voltage thus generated from the array
can be used to charge the chargeable Lithium
batteries, capacitors etc. These batteries can be used
as per the requirement.
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10. Sources of vibration for crystal
B. POWER GENERATING BOOTS OR SHOES
An idea is being researched by DARPA in the United
States in a project called Energy Harvesting, which
includes an attempt to power battlefield equipment
by piezoelectric generators embedded in soldiers'
boots. However, these energy harvesting sources by
association have an impact on the body. DARPA's
effort to harness 1-2 watts from continuous shoe
impact while walking were abandoned due to the
discomfort from the additional energy expended by a
person wearing the shoes.
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11. Sources of vibration for crystal
C. GYMS AND WORKPLACES
Researchers are also working on the idea of utilizing the
vibrations caused from the machines in the gym. At
workplaces, while sitting on the chair, energy can be stored in
the batteries by laying piezoelectric crystals in the chair. Also,
the studies are being carried out to utilize the vibrations in a
vehicle, like at clutches, gears, seats, shock-ups, foot rests.
D. MOBILE KEYPAD AND KEYBOARDS
The piezoelectric crystals can be laid down under the keys of a mobile unit and keyboards. For the
press of every key, the vibrations being created can be used for piezoelectric crystal and hence can
be used for charging purpose.
E. FLOOR MATS, TILES AND CARPETS
A series of crystals can be laid below the floor mats, tiles and carpets which are frequently uses at
public places.
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12. Sources of vibration for crystal
F. PEOPLE POWERED DANCE CLUBS
In Europe, certain nightclubs have already begun to power their night clubs, strobes and stereos
by use of piezoelectric crystals. The crystals are laid underneath the dance floor. When a bulk of
people use this dance floor, enormous amount of voltage is generated which can be used to power
the equipments of the night club
G. PIEZOELECTRIC WIND MILL
The piezoelectric wind mill consists of a fan with three blades to effectively capture the wind
flow. A disc is connected at the lower end of translator, such that whenever it moves upwards and
downwards, it compresses the piezoelectric crystals. Hence for different speeds of wind also, that
is for different frequencies, the Piezoelectric Wind mill may function. Hence, it has higher
workable bandwidth. The constant compression of piezoelectric crystals causes a huge amount of
energy to be generated, which can drive the remotely placed low power consuming devices.
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13. Applications of piezoelectricity
1. 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.
2. Ultrasound imaging
Piezoelectric sensors are used with high frequency sound in ultrasonic transducers for medical imaging .
For many sensing techniques, the sensor can act as both a sensor and an actuator. Ultrasonic transducers,
for example, can inject ultrasound waves into the body, receive the returned wave, and convert it to an
electrical signal (a voltage).
3. Sonar sensors
Piezoelectric elements are also used in the detection and generation of sonar waves. Applications include
power monitoring in high power applications such as medical treatment, sonochemistry and industrial
processing etc.
4. As chemical and biological sensors
Piezoelectric microbalances are used as very sensitive chemical and biological sensors. Piezo are also
used as strain gauges.
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14. Applications of piezoelectricity
5. In Music instruments
Piezoelectric transducers are used in electronic drum pads to detect the impact of the drummer’s sticks.
6. Automotive application
Automotive engine management systems use a piezoelectric transducer to detect detonation by sampling
the vibrations of the engine block. Ultrasonic piezosensors are used in the detection of acoustic emissions
in acoustic emission testing.
7. 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 single
crystal silicon. Since silicon is today the material of choice for integrated digital and analog circuits the
use of Piezoresistive silicon devices has been of great interest. It enables the easy integration of stress
sensors with Bipolar and CMOS circuits.
8. 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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15. Applications of piezoelectricity
5. In Music instruments
Piezoelectric transducers are used in electronic drum pads to detect the impact of the drummer’s sticks.
6. Automotive application
Automotive engine management systems use a piezoelectric transducer to detect detonation by sampling
the vibrations of the engine block. Ultrasonic piezosensors are used in the detection of acoustic emissions
in acoustic emission testing.
7. 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 single
crystal silicon. Since silicon is today the material of choice for integrated digital and analog circuits the
use of Piezoresistive silicon devices has been of great interest. It enables the easy integration of stress
sensors with Bipolar and CMOS circuits.
8. 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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16. Conclusion
 Flexible piezoelectric materials are attractive for power harvesting applications because of their
ability to withstand large amounts of strain.
 PZT materials that can convert the ambient vibration energy surrounding them into electrical energy.
This electrical energy can then be used to power other devices or stored for later use. This technology
has gained an increasing attention due to the recent advances in wireless and MEMS technology,
allowing sensors to be placed in remote locations and operate at very low power.
 The need for power harvesting devices is caused by the use batteries as power supplies for these
wireless electronics.
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17. References
[1]. Tomasz G. Zielinski, “ Fundamentals of piezoelectricity”, Institute Of Fundamental Technological
Research, Warsaw, Poland.
[2]. Tanvi Dikshit, Dhawal Shrivastava, (February 25 , 2010),“ Energy Harvesting via Piezoelectricity”,
ChameliDevi Institute of Technology and Management, School of Electronics, DAVV, Indore
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18. M.S.Ramaiah School of Advanced Studies 18

19. Sl.No Topic Max Marks Marks Awarded
1. Quality Of Slides 5
2. Clarity of subject 5
3. Presentation 5
4. Effort and Question 5
Handling
Total Marks = 20 =
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