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FOOTSTEP POWER GENERATION BY
PIEZOELECTRIC TRANSDUCER
NAME
ENROLLMENT NO
SIMRAN SINHA
510615078
RISHA
510615025
NIKHIL PRIYADARSH
510615022
AVIK DEY
510615021
SHAMIK BOSE
510615023
SOURADEEP SAHA
510615024
ARNAB JANA
510615089
HISTORY
 The word “Piezo” is basically meant for pressure.
 The piezoelectric effect was discovered by Jacques and
Pierre curie in 1880.They found that pressure applied to
a quartz crystal creates an electric charge in the crystal
and termed this phenomenon as direct piezoelectric
effect(electricity from applied stress).
 Later they also verified an electric field applied to the
crystal leads to a deformation of the material; inverse
piezoelectric effect. In the subsequent century,
research has been performed into the development of
materials with improved piezoelectric properties
,enabling commercial utilization of the piezoelectric
phenomenon.
PIEZOELECTRIC TRANSDUCER
AS ALTERNATE ENERGY SOURCE
•
•
At present, electricity has become a lifeline for
human population. Its demand is increasing
day by day. Modern technology needs a huge
amount of electrical power for its various
operations. Electricity production is the single
largest source of pollution in the whole world.
At one hand, rising concern about the gap
between demand and supply of electricity for
masses has highlighted the exploration of
alternate sources of energy and its sustainable
use.
Accordingly, it is an objective of the present
invention to provide a method of electrical
power generation from this ever increasing
human population that does not negatively
impact the environment. This technology is
based on a principle called the piezoelectric
effect, in which certain materials have the
ability to build up an electrical charge from
having pressure and strain applied to them.
 Harvesting of energy which means energy is already available,
but is going to waste if not utilized. Embedded piezoelectric
material can provide the magic of converting pressure exerted
by the moving people into electric current.
 We have only about 25 years of
oil reserves and 75 –100 years
of coal reserves. Resort to
measure beginning of coal in
thermal electric stations to
serve the population would
result in global elemental
change in leading to worldwide
drought and decertification.
 So, we have to think something
new. We have to think of nonrenewable source of energy. In
this new way of power
generation can be done as there
is no power from the mains and
there is less pollutions from this
source of energy
PIEZOELECTRIC TRANSDUCER
WORKING
 A transducer can be anything which converts one form of energy to
another. Piezoelectric material is one kind of transducers. We
squeeze this material or we apply force or pressure on this material
it converts it into electric voltage and this voltage is function of the
force or pressure applied to it. The material which behaves in such a
way is also known as piezoelectric sensor.
 Piezoelectric transducer consists of quartz crystal
which is made from silicon and oxygen arranged in
crystalline structure (SiO2). Generally, unit cell
(basic repeating unit) of all crystal is symmetrical
but in piezoelectric quartz crystal it is not.
Piezoelectric crystals are electrically neutral. The
atoms inside them may not be symmetrically
arranged but their electrical charges are balanced
means positive charges cancel out negative charge.
 The quartz crystal has unique property of
generating electrical polarity when mechanical
stress applied on it along certain plane. Basically,
there are two types of stress. One is compressive
stress and other is tensile stress.
 When there is unstressed quartz no charges induce
on it. In case of compressive stress, positive
charges are induced in one side and negative
charges are induced in opposite side. The crystal
size gets thinner and longer due to compressive
stress. In case of tensile stress, charges are
induced in reverse as compare to compressive
stress and quartz crystal gets shorter and fatter.
 Piezoelectric transducer is based on principle of piezoelectric
effect. The word piezoelectric is derived from Greek word piezen,
which means to squeeze or press. Piezoelectric effect states that
when mechanical stress or forces are applied on quartz crystal,
produce electrical charges on quartz crystal surface.
Theory
 The rate of charge produced will be
proportional to rate of change of
mechanical stress applied on it. Higher
will be stress higher will be voltage.
One of the unique characteristics of
piezoelectric effect is that it is
reversible means when voltage is
applied to them ,they tends to change
dimension along certain plane i.e.
quartz crystal structure is placed into
electric field, it will deform quartz
crystal by amount proportional to
strength of electric field. If same
structure is placed into an electric field
with direction of field reversed, the
deformation will be opposite. Quartz
crystal becomes longer due to electric
field applied.
 Quartz crystal becomes shorter due to electric field applied in
reversed direction. It is self generating transducer. It does not
require electric voltage source for operation. The electric voltage
produced by piezoelectric transducer is linearly varies to applied
stress or force. Piezoelectric transducer has high sensitivity.
EQUIVALENT CIRCUIT
 A piezoelectric transducer has very high DC
output impedance and can be modeled as a
proportional voltage source and filter network.
The voltage V at the source is directly
proportional to the applied force, pressure, or
strain. The output signal is then related to this
mechanical force as if it had passed through the
equivalent circuit.
 A detailed model includes the effects of the
sensor's mechanical construction and other nonidealities. The inductance Lm is due to the
seismic mass and inertia of the sensor itself. Ce is
inversely proportional to the mechanical elasticity
of the sensor. C0 represents the static
capacitance of the transducer, resulting from an
inertial mass of infinite size. Ri is the insulation
leakage resistance of the transducer element. If
the sensor is connected to a load resistance, this
also acts in parallel with the insulation resistance,
both increasing the high-pass cutoff frequency.
Piezo Sensor Array Construction:
 The array consists of 8 parallel branches each branch containing
two piezoelectric transducers connected in series.
 The lab report of one branch(2 piezos in series) gives an output of
approximately 5V terminal voltage and a short circuit current of
25uA
Output Voltage Waveform
Equivalent Circuit
 The foot-board has 16 piezoelectric transducers fit on the base.
 The upper surface of the foot-board has 16 screws fit downward
facing the piezo sensors.
 When someone steps on the board all the piezo sensors come in
Contact with the screws at once, thus a uniform pressure is applied
In all the piezos.
REGULATOR CIRCUIT
 In maintain is the polarity for the output generated to
be always positive (+ VE), the regulator circuit and
multiplier circuit are needed as shown in the figure.
Both circuit function as cut the negative charge and as
result the voltage produced is stable. The negative
voltage is not required because the circuit function is
for direct current (DC) mode.
 The regulator circuit and multiplier circuit also used as
to obtain a stable output voltage. If the output voltage
is not stable, the main goal to store the generated
voltage to battery may not be function is properly
because the circuit will not going to operate during the
unstable voltage. The output on the regulator circuit
and multiplier will be connected directly to the
rechargeable battery as temporary storage and 2.4
Volts rechargeable battery is used for it.
 This battery used is to store the voltage as temporary as to
support the main storage need to stabilize the voltage to
supply. With the charge stored in the battery; 2.4 Volts will be
used to charge a main battery as rechargeable batteries 12
Volts. To charge the battery, the converter circuit is used to
increase the voltage from the 2.4 Volts up to 12 Volts.
Regulator circuit
APPLICATIONS:
 POWER GENERATING SIDEWALK: Charging pads under the cross
walk collect energy from the vibrations. Then, piezoelectric
charging panels channel energy to lithium ion batteries which can
be used further.
 GYMS AND WORKPLACES: At workplaces, piezoelectric crystals
can be laid in the chairs for storing energy. Vibrations caused
from machines in the gyms can also be used for power
generations through piezoelectric sensors.
Power generating
sidewalk
 MOBILE KEYPADS AND KEYBOARDS: Crystals can be laid
down under keys of mobile unit and keyboard. For every
key pressed vibrations are created. These vibrations can
be used for charging purposes.
 POWER GENERATING BOOTS OR SHOES: We can use
piezoelectric sensors in the shoes which can produce
energy which can be stored in the battery.
 FLOOR MATS: Series of crystals can be laid down below
the floor mats, tiles and carpets of the dance club or big
railway stations. When mob uses the dance floor or the
railway station, an enormous voltage is generated. These
energy can be used.
Piezoelectricity in dance floor
Piezoelectric sensors
in shoe
ADVANTAGES AND
DISADVANTAGES:
ADVANTAGES
DISADVANTAGES
• Unaffected by
external electric field.
• They cannot be used
for truly static
measurements.
• Pollution free.
• Can pick up stray
voltages in connecting
wires.
• Low maintenance.
• Crystal is prone to
crack if overstressed
• Easy replacement of
equipment.
• May get affected by
long use at high
temperature.
We can use this method in IIEST,
Shibpur also for power generation.
We can install piezoelectric sensors
on the floors, on the playgrounds.
This can give rise of huge amount of
non-renewable energy which can
further use in the college as
electricity. Hope one day we can do
that.