Investigatory Project
Power Stride: Exploring the Feasibility and Applications of Piezoelectric Shoes
for Sustainable Energy Generation and Beyond
An Investigatory Project Presented to
The Faculty of Basic Education
Our Lady of Fatima University
In Partial Fulfillment of the Requirements for the Physics 2
By:
Mamon, Justine Hope L.
Sedano, Symond Rhizanne B.
Ward, Raizza Marie B.
Ms. Brianne C. Jimenez
Physics Professor
Date Submitted:
April 06, 2023
I.
Abstract
The Power Stride project aims to investigate the potential of piezoelectric shoes for sustainable
energy generation. Piezoelectric shoes are footwear that incorporates piezoelectric materials in their soles
to generate electricity through the piezoelectric effect when walking or running with it. This project
involves harnessing mechanical energy produced by human footsteps using piezoelectric materials and
converting it into electrical energy. The investigation will analyze and evaluate the efficiency and
effectiveness of the piezoelectric shoes in generating sustainable energy. This project will provide insights
for potential applications and benefits of piezoelectric shoes.
II.
Introduction
The Power Stride project was inspired by the need for sustainable energy sources and alternative
forms of renewable energy. Piezoelectric materials, which generate electric charges when subjected to
mechanical stress, have shown potential for energy harvesting. In this investigatory project, the physics
concept of piezoelectricity will be explored and applied to generate electricity from human footsteps.
III.
Lecture Review
Piezoelectric materials are a type of material that has the unique property of generating an electric
charge in response to mechanical stress or pressure. The term "piezo" is a Greek word meaning push. It
was discovered by Sir Jacques Curie and Pierre Curie in 1880. This phenomenon, known as the
piezoelectric effect, has been extensively studied in physics and has found numerous applications in
various fields, including energy harvesting, sensors, actuators, and other intelligent devices.
The physics behind piezoelectric shoes is based on the fundamental principles of piezoelectricity,
mechanical stress and strain, electric charge and current, electrical power and energy storage, and material
properties. The asymmetric arrangement of atoms or molecules in the crystal lattice structure of certain
materials, such as quartz, lead zirconate titanate (PZT), and polyvinylidene fluoride (PVDF), causes the
piezoelectric effect. When these materials are subjected to mechanical stress, the deformation causes a
shift in the position of the atoms or molecules, resulting in charge separation and the generation of an
electric charge on the material's surface.
The mechanical stress applied to piezoelectric materials in piezoelectric shoes is typically
generated by the wearer's body weight and motion during walking or running. As the person's foot hits the
ground, the piezoelectric material in the shoe's sole undergoes deformation and generates an electric
charge. This charge can then be harvested and converted into usable electrical energy to power electronic
devices or be stored for later use.
Moreover, the generated electric charge is characterized by its voltage and current, and the
electrical power generated by piezoelectric shoes is proportional to the product of these parameters.
Understanding the concepts of electric charge, current, and electrical power is crucial in designing an
efficient energy harvesting system for piezoelectric shoes.
Formulas:
Piezoelectric Equation
-
This equation describes the relationship between the electric charge generated in a piezoelectric
material and the applied mechanical stress or strain.
𝑡
𝑆 = 𝑠𝑇 + 𝑑 𝐸
𝐷 = 𝑑𝑇 + ε𝐸
Where:
S = Strain
sT = Stress
E = Electric field
D = Electric charge density displacement
dT = Matrix for the direct piezoelectric effect
ε = Permittivity
a. Suppose you have a piezoelectric material with a piezoelectric charge coefficient of d = 20 pC/N
and a dielectric constant of ε = 100. What is the resulting electric displacement if an electric field
of E = 50 V/m is applied to the material? Assume that the temperature is constant.
Formula: 𝐷 = 𝑑𝑇 + ε𝐸
Given:
−12
𝑑 = 20𝑥10
𝐶/𝑁
ε = 100 𝐹/𝑚
−12
ε0 = 8. 85𝑥10
𝐹/𝑚
𝐸 = 50 𝑉/𝑚
Solution:
−12
𝐷 = (20𝑥10
−12
𝐶/𝑁)( 𝑇) + (100 𝐹/𝑚 𝑥8. 85𝑥10
𝐹/𝑚)(50 𝑉/𝑚)
Answer:
−12
𝐷 = (20𝑥10
−8
𝐶/𝑁)( 𝑇) + 4. 425𝑥10
2
𝐶/𝑚
Mechanical Stress Formula
-
This formula calculates the mechanical stress applied to the piezoelectric material, which is the
force applied per unit area of the material.
𝑠 =
𝐹
𝐴
Where:
s = Stress
F = Applied force
A = Unit area
2
b. Suppose a person is wearing piezoelectric shoes with a surface area of 50𝑖𝑛 . What is the stress
experienced by the piezoelectric material if a person walks on a hard surface and exerts a force of
400 pounds on the shoes?
Formula: 𝐹 = 𝑚𝑔, 𝑠 =
Given:
𝐹
𝐴
2
A = 50 𝑖𝑛
F = 400 lbs.
Solution:
0.454 𝑘𝑔
1 𝑙𝑏.
𝐹 = 400 𝑙𝑏𝑠. 𝑥
2
𝑥 9. 8𝑚/𝑠
𝐹 = 1779. 68 𝑁
2
𝐴 = 50𝑖𝑛 𝑥 (
0.0254𝑚 2
)
1𝑖𝑛
2
𝐴 = 0. 03𝑚
𝑠 =
1779.68 𝑁
2
0.03 𝑚
Answer:
𝑠 = 59322. 67 𝑘𝑃𝑎
Electrical Power Formula
-
This formula calculates the power generated by the piezoelectric material, which is the rate at
which energy is transferred or converted.
𝑃 = 𝑉𝐼
Where:
P = Power
V = Voltage
I = Current
c. Suppose a person is wearing piezoelectric shoes that can generate an electric charge of 0.5 volts
when compressed. The person takes 10 steps per minute, and each step exerts a force of 50
newtons on the piezoelectric material in the shoes. If the shoes have an internal resistance of 10
ohms, what is the power generated by the shoes?
Formula: 𝑉 = 𝐸𝑑, V = IR, 𝑃 = 𝑉𝐼
Given:
E = 0.5 V
d = 50 N
R = 10Ω
Solution:
𝑉 = 0. 5 𝑉 𝑥 50 𝑁
𝑉 = 25 𝐽
𝑉 = 𝐼𝑅 → 𝐼 =
𝐼=
25 𝐽
10Ω
𝐼=
25 𝐽
10Ω
𝑉
𝑅
𝐼 = 2. 5 𝐴
𝑃 = 0. 5 𝑉 𝑥 2. 5 𝐴
Answer:
𝑃 = 1. 25 𝑊
IV.
Procedure and Mechanics
Here are all the materials that will be used in the project. Some materials are more important than
others and can be reconsidered and substituted with other materials if unavailable.
Materials:
●
27mm Piezo Disc Transducer
●
Wearable Shoes
●
1N4007 Diodes
●
Soldering Iron
●
3.7V Battery
●
Soldering Iron Lead
●
Power Bank Charging Module
●
Glue Gun
●
Battery Case
●
Rotary Tool
●
Black & Red Wires
●
Saw Bow
●
Scissors
●
Marking Pen
●
Multimeter Tester
●
Transparent Hard Clear PVC
●
Diagonal Pliers
●
Double-sided Tape
●
Wire Tweezers
●
Silicone Adhesive
●
Thin PVC Board
●
Spare Shoe Insole
Procedures:
1. Gather all the materials that will be needed to make the piezoelectric shoes.
2. Trace the sole of the shoe in the thin PVC board and saw it according to the markings.
3. Make a hole in the thin PVC using the rotary tool where the piezo disc transducers will be placed.
4. Place all the piezo disc transducers on the holes and secure them using a silicone adhesive.
5. Cut small circles in the spare shoe insoles and glue them on the posterior part of the piezo disc
transducers.
6. Attach the other set of the piezo piece transducers on the opposite side.
7. Connect the piezo disc transducers by soldering the ends of the red wire to the positive terminal
and the black wires to the negative terminal of the piezo disc transducers. Ensure that there are no
loose connections.
8. Connect the ends of the four diodes together and connect it with the piezo disc transducers.
9. Make small circles using the spare shoe insole again and glue in the middle of the piezo disc
transducers using the silicone adhesive.
10. Place the transparent hard clear PVC on top of the spare shoe insole circle.
11. From here, there are two viable options:
-
Attach the power bank charging module to the battery case, solder the wire of the battery
case to the board of the power bank module, and glue it to the side of the battery case
before proceeding to the next step.
-
Or, without the battery case and only the power bank module, proceed to the next step.
(Note that the battery case will allow storage for electricity and charging of batteries.)
12. Secure the battery case or the power bank module at the side of the shoe. Then place the
piezoelectric device under the sole of the shoe. Make way for the wire that will connect the two
pieces together.
13. Finally, test it by trying it out and measuring its electric capacity by using a multimeter tester.
V.
Significance of the Study
This project seeks to address important issues related to sustainable energy generation,
environmental conservation, and human well-being. Here are some key points of significance for this
project:
1. To Generate Sustainable Energy. This could provide a sustainable and renewable energy source
that can power some devices or systems by harnessing mechanical energy generated in walking or
running and converting it into electrical energy. With this, reliance on non-renewable sources of
energy could be reduced, contributing to global efforts to mitigate climate change.
2. To Conserve the Environment. Piezoelectric shoes have the potential to generate electricity
without producing harmful emission, pollution, or waste and by utilizing it as means of energy
generation, it can reduce carbon footprint associated with traditional energy sources. This could
be an environmentally friendly alternative for energy generation.
3. For Human Well-being. The use of piezoelectric shoes could promote physical activity and
wellness by encouraging individuals to engage in physical movements. Additionally, in areas
where access to electricity is limited, this could provide means of generating electricity to power
essential devices such as communication tools, lighting, or medical equipment.
4. Technological Innovation. This investigatory project could contribute to the advancement of
piezoelectric technology and its application. By exploring the feasibility of piezoelectric shoes, it
could improve the efficiency and effectiveness of piezoelectric generation through discovering
new designs, materials, and techniques.
VI.
Bibliography
Ahmad, N., Jamshaid, R., & Rafique, M. T. (2020, June 19). (PDF) Design of Piezoelectricity Harvester using
Footwear. ResearchGate. Retrieved April 6, 2023, from
https://www.researchgate.net/publication/342223221_Design_of_Piezoelectricity_Harvester_using_Foot
wear
The behavior laws of piezoelectricity. (n.d.). OnScale. Retrieved April 6, 2023, from
https://onscale.com/piezoelectricity/the-behavior-laws-of-piezoelectricity
Electric Power - Definition, Formula, Solved Examples | Electric Energy. (n.d.). Byju's. Retrieved April 6, 2023,
from https://byjus.com/physics/electric-power/
Haynes, A., & Rislov, E. (2016). Piezoelectric Shoes: Charge Your Mobile Device by Walking! Instructables.
Retrieved April 6, 2023, from
https://www.instructables.com/Piezoelectric-Shoes-Charge-Your-Mobile-Device-by-W/
Mends, F. (2020, December 28). What Are Piezoelectric Materials? Sciencing. Retrieved April 5, 2023, from
https://sciencing.com/piezoelectric-materials-8251088.html
Piezoelectric Materials: Equation, Working, Advantages and Limitations. (2013). ElProCus. Retrieved April 6,
2023, from https://www.elprocus.com/what-is-a-piezoelectric-material-working/
Stress Equation Definition - Strength ( Mechanics ) of Materials. (n.d.). Engineers Edge. Retrieved April 6, 2023,
from https://www.engineersedge.com/material_science/stress_definition.htm