Piezoelectric Mat

i

DESIGN AND SIMULATION OF ENERGY HARVESTING PIEZOELECTRIC PUZZLE FLOOR MAT USING PIEZOELECTRIC CRYSTALS

A thesis presented to the College of Engineering of FEU – Institute of Technology

In partial fulfillment of the requirement for the Degree of Bachelor of Science In Electronics Engineering

By

Magluyan, Pamela Kim Donnelle G. Capati, Aubrey Sharmaine M. Postre, Raul Christian M.

Engr. Luigi Carlo M. De Jesus Adviser

Engr. King Harold H. Recto Faculty in Charge

January 2016

ii Table of Contents Page No. Title Page

i

Table of Contents

ii

List of Tables

iii

List of Figures

iv

Chapter 1 Introduction

1

Background of the Study

1

Statement of the Problem

4

General Objective

5

Specific Objective

5

Scope and Delimitation

5

Significance of Study

7

Definition of Terms

8

Chapter 2 Review of Related Works and Literature Review of Related Materials

9 9

Floor Mats

9

Rubber Sheets

10

Piezoelectric Transducer

11

Piezoelectric Crystals

11

Lithium-ion Battery

11

Full-Wave Rectifier

14

Bridge Full Wave Rectifier

14

ii Step – up Chopper

16

Compression Springs

16

Working Theories

16

Energy Harvesting

16

Piezoelectricity

18

How Piezoelectric Effect Works

18

Frequency of Oscillation

19

Cascaded Operational Amplifier Circuit

19

Review of Related Works and Studies Foreign Works and Studies

20 20

Japan Harnesses Energy from Footsteps

20

A Shoe-Embedded Piezoelectric Energy

22

Harvester for Wearable Sensors Source of Vibration for Crystal Previous Work

24

Power Generating Sidewalk

24

Power Generating Boots or Shoes

24

Gyms and Workplaces

25

Mobile Keypad and Keyboards

25

Floor Mats, Tiles and Carpets

26

People Powered Dance Clubs

26

Piezoelectric Energy Harvesting

26

ii Local Works and Studies In-Wheel Piezoelectric Generator for

28 28

Lighting Application of Mining Trolleys Energy-Harnessing Footwear Using

29

Combined Electromechanical And Piezoelectric Transducers for Charging Supercapacitors (2009 ) Power Generation for Remote Areas Utilizing

30

Piezoelectric Transducers Harnessing Wind and Wave Energy (2011)

Chapter 3 Research Methodology

31

Conceptual Framework

31

Block Diagram

32

Schematic Diagram

33

Full-Wave Bridge Rectifier

34

Step-Up Chopper (DC/DC converter)

35

Lithium-ion Battery

35

PCB Layout

36

Flow Chart of Process

37

Test Population

39

Treatment of Data

39

Calculations for the number of trials

39

ii Calculation for the Tolerance

40

Testing Procedure

41

Proposed Table for Test Results

41

Proposed Project

43

Ideal Set up

43

Design Considerations of Puzzle Floor Mat

43

References

49

Appendices Appendix A

Chi-Square Critical Values Table

52

Appendix B

Bill of Materials

54

Appendix C

Gantt Chart

55

Appendix D

Average Weight of Students in

56

FEU-Institute of Technology Appendix E

Data of Average Students that Entered

60

the School Premises Appendix F

Consultation Sheet

64

iii List of Tables Figure No.

Description

Page No.

1

Specifications of Lithium-ion Battery

36

2

Proposed Table for Test Results

41

3

Specifications of Smaller Spring

46

4

Specifications of the Bigger Springs as a support

47

iv List of Figures Figure No.

Description

Page No.

1

Charging and discharging phenomena in Lithium Ion batteries

13

2

Bridge Full-Wave Rectifier

14

3

Commuters at the Tokyo station walk on a piezoelectric sheet

22

which generates electricity when pedestrians step on it 4

A Shoe-Embedded Piezoelectric Energy Harvester

23

for Wearable Sensor 5

Energy Harvested of Phase 1 and Phase II

28

6

Energy Harvesting Shoe

30

7

Conceptual Framework

31

8

Block Diagram

32

9

Circuit Diagram of the System

33

10

Full-Wave Bridge Rectifier

34

11

Lithium-ion Battery

35

12

PCB Layout

36

13

System Flowchart

37

14

Ideal Set up: A man stepping on the floor mat

43

15

Dimensions of the Puzzle Floor Mat

43

16

Top View of the Puzzle Floor Mat

44

17

Inner Part of the Puzzle Floor Mat

45

18

Comparison of design with respect to vibrations

48

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Chapter I Introduction 1.1 Background of the Study Technology has evolved and became more advanced over the past decades and along with this, the sources of energy that can power up electronics became more industrialized. Most energy sources have been depleting due to a great demand from its increasing population. It is a given fact that the country has been battling with energy sources that would supply electricity. Manila and other cities had experienced black – outs or power outages in earlier months of year 2015, specifically April to May because of the shortage of supply of electricity [1]. Some of the energy sources like Malampaya have been closed for operating due to weather or climate conditions. The main energy sources which can be harvested are categorized in mechanical energy from vibrations, thermal energy, solar energy, biomass and fossil fuels. Another significant source of energy which is often overlooked is the human body. Human body can generate a significant amount of energy through footsteps. The human waste foot energy is being used to produce electricity which is a great evolution in electricity generation. The average human can take 3,000 – 5,000 steps a day [2]. Some of the energy wasted when human walks which is in the form of vibrations can be converted into an electrical energy using Piezoelectric Crystals. Any form of vibration like footsteps, heartbeats, etc. can generate electricity to activate electronic devices [3]. The

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concept of piezoelectricity can be applied as actuators, transducers, motors, and even sensors wherein different kinds of materials are used like crystals and strips. The harvesting of energy of a piezoelectric material is not affected by weather or climate conditions. Piezoelectric materials generate energy through vibrations or pressure like footsteps unlike energies from water, sun, wind and etc. Piezoelectricity are massively used in foreign countries and even in the Philippines. However, it is mainly used as a transducer in the Philippines. One example is a microphone where it receives sound waves that are converted into electrical energy with the use of Piezoelectric Crystals. Piezoelectric Crystals are also used in electric cigarette lighter. Piezoelectricity has not been used as a large source of energy in the Philippines. In Japan, piezoelectric floor tiles are used to operate the train – ticketing systems. These floor tiles converts the vibrations of footsteps into electrical energy in which the capacity of one footstep can provide enough electrical current to light two 60 – watts bulb for one second [4]. The mass of the person stepping on the floor mat has an effect regarding the energy output and design consideration. If the person is heavy, the force on the floor mat is much larger than a light person. On the other hand, the design of floor mat has its limited weight capacity until it breaks. Using the sample data gathered by the researchers, the average weight of a person in FEU – Institute of Technology is about 63 kilograms. Through considering the materials that will be used on the project, the researchers were able to compute the estimated maximum weight capacity of the floor mat which is 36,993 kilograms.

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Most existing piezoelectric energy harvesting floors used floor tiles. Floor tiles usually provide a hard surface. Unlike floor mats that are usually made of cloth and rubber which are soft. An impact is a high force or shock which is applied over a short period of time once two or more bodies collide whether elastic or inelastic [5]. A theory in Engineering Mechanics states that impact strength, expressed in amount of energy absorbed before fracture, decreases per increase in the modulus of elasticity which means stiff materials will have less impact strength than supple materials [5]. Soft surfaces like floor mats can produce more oscillations. Piezoelectric Floor Tiles used ceramic tiles that are heavier than Puzzle Floor Mat which uses rubber sheets. The mass of the upper layer of the mat which is the rubber sheets will produce more vibrations than the mass of the ceramic tile. The concept of frequency of oscillation states that the frequency is inversely proportional to the mass of the person [6]. The heavier the person, the lower oscillation frequency will be produced. A low frequency of oscillations will produce longer period of time. Thus, it will have a greater generated output energy. Puzzle Floor Mats are connected mats in which the circuit of each mat are connected in series. Cascading of operational amplifiers is done through connecting each op – amps in series, thus, increasing the total gain. The gain is directly proportional to the voltage output [7]. Batteries that are cascaded in series produce a higher voltage output. The Puzzle Floor Mats are cascaded like cascading op – amps or batteries in which it increases the voltage output of the whole Puzzle Floor Mat. With the aid of the facts, the proponents therefore offer to design an EnergyHarvesting Piezoelectric Puzzle Floor Mat using Piezoelectric Crystals. Instead of floor

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tiles, which are usually made by clay or ceramics, a Puzzle Floor Mat will be used to generate electrical energy through footsteps. These mats are made of rubber sheets which are soft and elastic that will produce greater and longer vibrations. Greater and longer vibrations will produce more energy to be converted. The added parameters of the proponents’ study are the output energy of the Piezoelectric Puzzle Floor Mat, installation and cost, weight of the project, as well as the operability and maintenance. The output energy is the most significant parameter because it will help in determining which devices it can supply. Installation of these floor mats are very easy and low cost because it does not need to be installed like floor tiles. It can just be laid down on the floor and materials that will be used are cheaper and available in the Philippines. In addition, the frequency of oscillations of the spring has an influence on the vibrations produced by the project. The weight of the person stepping on the mat affects the frequency of oscillations which means it is also an important parameter to be determined. Lastly, the operability and maintenance of the project is very simple since it can be moved in different places and easy to fix when something is wrong. 1.2 Statement of the Problem Sources of energy in the Philippines have been diminishing because of a big demand due to the increasing population in the country. The increasing demand in energy impels researchers to find a renewable alternative sources. Piezoelectricity is a technology in harnessing energy used in foreign countries as an alternative source. Various energy harvesting piezoelectric devices have been developed like Piezoelectric Floor Tiles.

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The current study will design and localize existing Energy Harvesting Piezoelectric Puzzle Floor mats. Puzzle Floor Mats will have a soft surface because it is made of rubber sheets, hence making a longer and larger vibration due to the springs. It will also be cascaded for a larger energy output. This study will contribute regarding the problem of declining energy source of the country by using Piezoelectric Puzzle Floor Mat which harness energy through oscillation. 1.3 General Objective: To design and simulate the harnessing of energy of a Piezoelectric Puzzle Floor Mat using Piezoelectric Crystals 1.4 Specific Objective: 

To design a rubber Puzzle Floor Mat using Piezoelectric Crystal in converting mechanical energy to electrical energy



To design a circuit for harnessing, monitoring and storing of the electrical energy converted



To design a Piezoelectric floor mat which produce larger and longer vibrations



To attain an appropriate energy output of 2.5 Joules per step or higher of the Puzzle Floor Mat through continuous testing

1.5 Scope and Delimitation This study will also focus on harvesting energy of the Puzzle Floor Mat that has a dimension of 20” by 20” by 3”. Each floor mat will have at least 25 piezoelectric crystals, 25 springs, and another 4 big springs in the inner part of the mat which is beside

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the piezoelectric crystals that will contribute in producing more vibrations. Furthermore, this study will use a lithium – ion battery with 3.7 volts voltage output. The generated energy may depend on the weight of the person stepping on the mat. A maximum of two persons can step on one mat. This study will only be implemented indoors where many people are passing like building entrance or lobbies. It can also be moved to different places. This study will monitor the output energy per step manually using an energy or V/I meter. This study will use plugs that will help in cascading the floor mats. The exposed jacks and plugs will have specific coverings for protection against any liquid. However, the floor mat itself should not be soaked too much with water because materials are not water proof. The floor mat should be cleaned every day. The most common issue about the maintenance of rubber floor mats is dirt and small debris which comes from the shoes and slippers. In cleaning the floor mats, a vacuum or manual gentle scrubbing can be applied. According to the data we gathered from the clinic, the average weight of the students that are enrolled in FEU-Institute of Technology is 63kg. The maximum weight that the floor mat can withstand is 36,993 kg. Therefore, any person can step on the floor mat. During testing, the researchers will use a controlled environment. Only one person, weighing exactly 63 kg, will step on the mat. The person should step on the mat in his natural way of walking. Moreover, using a controlled environment, the researchers will be able to determine whether the energy is constant at every trial. This will not include the study of any kind of tiles. The proponents will use a mat that is made of rubber sheet which is water resistant in order to avoid any damage in the

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internal parts of the mat in case that it will be wet. In addition, the Puzzle Floor Mat will not generate energy if the foot is still on the mat unless the foot is removed. 1.6 Significance of Study The electric energy consumption during 2010 was 64.52 billion kilowatt-hours in the Philippines, which accelerated from 48.96 billion kilowatt-hours in the year 2013. The electrical energy consumed in 2014 was 56.84 billion kilowatt-hours which was ranked as 41st worldwide [9].This study will recommend a way to help lower the electrical energy consumed annually by utilizing energy that is being dissipated by human beings regularly. When a person is walking, an energy is formed through footsteps or vibrations and can be converted into electrical energy. The harvested energy from human footsteps is large enough to operate an electrical appliance/s and other equipment which is costless. This project can also be placed in sidewalks to energy the stoplights and the streetlamp since more footsteps from people walking through the Puzzle Floor Mat will generate more energy. This study may help energy the lights in the hallways of the schools and other business companies from the employees or students that are walking through the Puzzle Floor Mat. Materials that would be used in this study are locally available which is an advantage since importation of the materials will no longer be needed. The future researchers can enhance and develop the features and specifications of the project as a recommendation. The Piezoelectric Puzzle Floor Mat can be converted into a water proof floor mat. Floods caused by typhoons are not new in the Philippines. If it is converted into water proof floor mats, it can be placed in the sidewalks where pedestrians can walk through it and can still accumulate vibrations regardless of the

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heavy rain and the flood. Moreover, since raindrops can create vibrations when it falls to the mat, it can still generate energy during rainy days. Definition of Terms Piezoelectricity. The concept used in the project wherein it has the ability of a material to produce an AC voltage from a mechanical energy in a form of vibrations or stress specifically human footsteps. It also called as piezoelectric effect. Piezoelectric transducer. It involves a crystal between two plates which form vibrations and converts the vibrations to weak AC voltage. Energy harvesting. A method of collecting small amount of energy which is in a form of heat, light, sound, vibrations or movement. In this study, energy can be harvested through vibrations and movement and will be used to convert into an electrical energy using Piezoelectric Puzzle Floor Mat. Water resistant. The ability to resist the penetration of water in some certain depth but not entirely and one key feature of the Piezoelectric Floor Mat. Oscillations. Produced by the vibrations. Cascade. Connecting the circuit of each Piezoelectric Puzzle Floor Mats in series. Op – amps. Stands for Operational Amplifiers.

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Chapter II Review of Related Literature This chapter discusses the review of related literature about Energy Harvesting Piezoelectric Puzzle Floor Mats. It explains relevant concepts and materials involving with the current study to provide the foundation of the proposed study.

2.1 Review of Related Materials 2.1.1 Floor Mats Floor Mats are standard equipment commonly used in vehicles which have carpet covering floor. Floor mats are usually flat and typically consist of a thin layer of lightweight carpeting bonded to a thin layer of polymer type material that blocks water from getting through [10]. Pros: 

Softness and Elasticity of the Floor Mat  Floor Mats are soft and elastic and when a foot steps on it, it cause vibrations. These vibrations last longer in soft materials which cause to produce more mechanical energy that will be converted to electrical energy.

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2.1.2 Rubber Sheets Rubber sheets are essentially polymers of isoprene. These rubber sheets are elastic materials that is achieved by thickening and drying the latex from certain plants which is the milky juice of any of various tropical plants like genera Hevea and Ficus. Later prepared as sheets [11]. Pros: 

Durability  Rubber sheets are strong and resilient against a variety of conditions. If it installed properly, it can last for a long time.



Soft  Given the fact that the material is strong and can last for a long time, rubbers are actually soft.



Water resistant  Rubber materials are not absorbent of water or liquid which there’s no concerns about damage from simple liquid spills.

Cons: 

Slippage  If rubbers are not textured, it can become slippery when liquid is spilled on it.

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

Dull finish  The appearance of the rubber sheets are unattractive to many people which is why it is not a common option for floorings where many people can see it.



Difficulty in Cleaning  Rubbers picks up grease so easy and have a tendency to discolor when detergents are used for cleaning.

2.1.3 Piezoelectric Transducer Piezoelectric transducer is a device that converts one type of energy to another by using the piezoelectric properties of certain crystals or other materials [12]. It generates an electrical potential or voltage when a force or pressure is applied onto the piezoelectric device or material. Piezoelectric transducers are epitome of a good converter of mechanical energy to electrical. 2.1.4 Piezoelectric Crystals Piezoelectric Crystals is a small scale energy sources. When these crystals are squeezed, a vibration occurs that produces a very small voltage. These crystals bend in different directions at different frequencies in which this bending is called the vibration mode [13]. 2.1.5 Lithium-ion Battery Lithium-ion is a rechargeable battery and is composed of one or more cell. A cell has a positive electrode that is connected to a battery’s positive terminal. A cell also has a negative electrode that is connected to the negative terminal.

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Electrolyte is a chemical that is between the negative terminal and positive terminal of the cell. A battery is said to be a lithium-ion if the movement of ions is one way when charging and when it moves the opposite way while the battery is discharging. [14] Pros: 

Light weight -

Lithium-ion batteries have the same weight with the other rechargeable batteries but lithium-ion batteries are light weight.



High energy density -

Lithium-ion batteries can store lots of energy in it because of very high energy density and the battery is made of light weight lithium and carbon. The lithium in the battery is also a highly reactive element.



Convenient -

A lithium-ion battery that weighs 1 kilogram can store the same amount of energy which a 6 kilograms lead-acid battery can store.



Charging and discharging cycle -

Lithium-ion batteries can handle many charging and discharging cycles

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Cons: 

Short life span -

Lithium-ion batteries that either used or unused have a short life span of 2 to 3 years from the date of manufacture.



Temperature exposure -

Lithium-ion

batteries

are very sensitive to

high

temperature hence they tend to degrade much faster when exposed to heat.

Figure 1. Charging and discharging phenomena in Lithium Ion batteries

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This figure shows a lithium-ion batteries while charging and discharging. A lithium-ion battery is charging when a chemical compound in the positive electrode gives up a few of the lithium ions, where it travels to the chemical compound in the negative electrode and remain there. The battery will store energy to absorb energy. The battery is discharging when the lithium-ions from the negative electrode will move back across the electrolyte to the positive electrode to produce energy from the battery since the electrons flow around the circuit on the opposite way to the ions. Lithium is deposited on the positive electrode if the ions and electrons will combine in the positive electrode [14]. 2.1.6 Full-Wave Rectifier There are 4 diodes in the full-wave rectifier circuit. All the diodes are connected with each other and are forward-biased. Each diode conducts for 180º of the input cycle. The frequency of the output in a full-wave rectifier is twice the input frequency [15]. 2.1.6.1 Bridge Full Wave Rectifier

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Figure 2. Bridge Full-Wave Rectifier This figure shows an image of Bridge Full-Wave Rectifier Circuit. The first diode (D1) and the second diode (D2) are said to conduct current during the positive half-cycle of the input in the bridge-full wave rectifier operation. A voltage is developed across the load resistor (RL) that resembles the positive half of the input cycle. Meanwhile, the remaining diodes D3 and D4 are reverse-biased. During the negative half-cycle of the input in the bridge-full wave rectifier operation, the third diode (D3) and fourth diode (D4) conduct current in the same direction through the load resistor (RL) as during the positive half-cycle. Meanwhile, the other diodes which are D1 and D2 are reverse-biased. A full-wave rectified output voltage appears across the load resistor (RL) as an outcome [15].

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2.1.7 Step – up Chopper The supply of the step-up chopper is a rectified AC or a battery. The purpose of a chopper is to improve the DC voltage by converting the fixed DC voltage into a variable DC voltage. A chopper is a high speed switch that connects and disconnects the load from the source to attain a variable DV output voltage. Chopper is also known as DC transformer. A step-up chopper is also known as boost converter which is used to step-up the voltage from its input side [16]. 2.1.8 Compression Springs Compression springs is an open coil – helical spring which is usually coiled as a constant – diameter cylinder. When compression force from a load is applied to the spring, the spring then becomes squeezed. However, with the design of wires, it tries to go back to its original shape thus pushing the load back [17].

2.2 Working Theories 2.2.1 Energy Harvesting Energy Harvesting is the process of acquiring amounts of energy from one or more natural sources of energy and storing them for future use. Energy Harvesting plays a vital role in distributing energy to certain applications. It uses devices which enables to acquire, store, convert and manage efficiently and effectively the generated energy and supply it in a form that can be used to

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perform a helpful task [18]. Moreover, Energy Harvesting, from natural sources where an application can be implemented and sources of natural energy is limitless, is an alternative source of energy to wall plugs and batteries which are inconvenient

and

costly.

Energy

Harvesting

includes

photovoltaics,

thermovoltaics, piezoelectrics, electrodynamics and many more. Energy harvesting has its advantages and disadvantages which are enumerated below [19]. Pros: 

Renewable and Abundance  Harvested energy can be manufactured quickly, and require no other source of energy to operate. One good example is wind. Wind is a limitless, naturally occurring phenomenon that is present over the world, and represents a clean and renewable domestic energy resource.



Cost – effectiveness and continuing improvement of performance  Natural sources of energy costs less since it can be generated through air, water, vibrations, sun and etc. Moreover, the performance of the energy harvesting system can be enhance.



Can be combined into smart integrated energy system  The harvested energy can easily be incorporated with smart energy systems. Also, different technologies can be

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combined like monitoring systems using Bluetooth, Zigbee and other technologies. Cons: 

Variable amount of energy generated  There is inconsistency with the amount of energy generated with natural sources of energy. For an example, energy generated through footsteps, the number of people that will step in the energy harvesting devices will never be constant making the generated energy varying.

2.2.2 Piezoelectricity Piezoelectricity, also called the piezoelectric effect, is the produce of electric potential or voltage from the crystals when mechanical stress is applied through squeezing and deforming the crystal [20]. Piezoelectric effect has a unique characteristics wherein it is reversible. It can function as a direct piezoelectric effect where stress is applied to generate electricity. It can also function as a converse piezoelectric effect where electric field is applied to generate stress [21]. 2.2.2.1 How Piezoelectric Effect Works The charges in a piezoelectric crystal are normally balanced even if it is not symmetrically arranged. Before exposing the material to pressure and stress, the centres of the positive and negative charges of each molecule concur wherein the charges are reciprocally cancelled.

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Consequently, electrically neutral molecule appears. The piezoelectric effect happens when the balanced and neutral charge is disturbed through squeezing the crystals which causes the separation of the positive and negative charges of the molecules where little dipoles are created. Subsequently, the facing dipoles inside the material are both cancelled. The material becomes polarized because of the distributed linked charges. When the crystal lattice is distorted, the imbalance of the charge creates a potential difference. This potential difference is also known as the voltage [22]. 2.2.3 Frequency of Oscillation The oscillation frequency expands as the stiffness of the spring increases. The frequency of oscillation also expands if the reduction on the mass attached to the spring is applied [24]. The frequency of oscillation is measure in cycles per second is mathematically expressed as:

𝑓=

1 2𝜋

√

𝑘

Equation 2.2.4

𝑀

𝑘𝑔

Where: k = spring constant ( 𝑠2 ) M = mass (kg) 2.2.4 Cascaded Operational Amplifier Circuit The cascaded operational amplifier circuits produce higher voltage gain. An operational amplifier is in cascade connection if the output of an operational

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amplifier circuit is the input of the next operational amplifier circuit. The total output gain of the cascaded operational amplifier is the product of the individual operational amplifier circuits [25]. If there are 3 operational amplifier circuits given, the overall gain in cascade connection will be mathematically expressed as: 𝐴 = 𝐴1 𝑥 𝐴2 𝑥 𝐴3

Equation 2.2.5

Where: A1 = stage 1 or 1st gain in the operational amplifier circuit A2 = stage 2 or 2nd gain in the operational amplifier circuit A3 = stage 3 or 3rd gain in the operational amplifier circuit

The gain is directly proportional to the voltage output of the operational amplifier circuit, hence when the gain increases the voltage output also increases.

2.3 Review of Related Works and Studies 2.3.1 Foreign Works and Studies 2.3.1.1 Japan Harnesses Energy from Footsteps In Japan, special flooring tiles made of rubber sheeting and stoneware tiles are installed in their ticket turnstiles. These flooring tiles generates energy from footsteps. The idea behind this is piezoelectricity. Every steps of the passenger generates a vibration that acts as an energy. The purpose of rubber sheeting is to absorb the vibrations of the steps

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made by the people who uses the station. This energy will be multiplied by the number of people who crosses the station. Like in Tokyo station, the energy will be multiplied over the 400,000 people who crosses the station in an average day and this energies are sufficient to light up the electronic signboards, according to East Japan Railway. Takuya Ikeba, a spokesperson in JR East, said that “We are just testing the system at the moment to examine its full potential". Same concept is applied in Shibuya station wherein on an average week, 2.4 million people passes through this station. Soundenergy Corp. applied the “Energy Generation Floor”. Yoshiaki Takuya, a planner with Soundenergy Corp. said that "An average person, weighing 60 kg, will generate only 0.1 watt in the single second required to take two steps across the tile. But when they are covering a large area of floor space and thousands of people are stepping or jumping on them, then we can generate significant amounts of energy." The generated energies can be stored in a capacitor and can be distributed to the part of the station including the electrical lighting system and the ticket gates. It is important to know the generated output energy so that it can easily determine what type of low energy device it can only energy up [26].

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Figure 3. Commuters at the Tokyo station walk on a piezoelectric sheet which generates electricity when pedestrians step on it This figure shows the application of piezoelectric floor tiles in Tokyo, Japan. It is used to energy up electrical lighting system and the ticket gates in train stations. These floor tiles uses a capacitor as a storage. 2.3.1.2 A Shoe-Embedded Piezoelectric Energy Harvester for Wearable Sensors An interesting approach for acquiring a clean and sustainable electrical energy to energy wearable sensors, that are used for health monitoring, activity recognition, gait analysis and so on, is harvesting mechanical energy from human locomotion. This study focused on a piezoelectric energy harvester for the parasitic mechanical energy in shoes which came from human locomotion. A sandwich structure is designed

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for the harvester to fit and be compatible with the shoes as well as a consideration for both high performance and excellent durability. An average output energy of 1mW during a walk at a frequency of roughly 1Hz is obtained from the harvester. Through integrating the harvester with a energy management circuit, a direct current (DC) energy supply is created. The DC energy supply is verified by driving a simulated wireless transmitter that can be activated once every 2 – 3 steps with an active period lasting 5ms and a mean energy of 50 mW. Hence, this study illustrates the feasibility of using piezoelectric energy harvesters in energying wearable sensors. Wearable sensors are becoming smaller and are frequently used by many which indicates that a need for portable source of electrical energy is important [27].

Figure 4. A Shoe-Embedded Piezoelectric Energy Harvester for Wearable Sensors

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This figure shows the design of the shoe embedded piezoelectric energy harvester for wearable sensors. Inside the shoes is the harvester which contains the energy management circuit and the DC energy supply. The harvester is mounted inside the shoes with a wearable sensors to generate electrical energy. 2.3.1.3 Source of Vibration for Crystal Previous Work [28] 2.3.1.3.1 Power Generating Sidewalk The series connection of piezoelectric crystals are located under the walking section of the pedestrians on sidewalks and pavements. Batteries like lithium and capacitors will be charged by receiving the generated voltage from the piezoelectric crystals in series. The limitation in the usage of the batteries will depend on the received generated voltage from the crystals arranged in series connection. 2.3.1.3.2 Power Generating Boots or Shoes A groundbreaking design for operating battlefield equipment where a mechanical energy will be converted into an electrical energy was proposed by the United States Defense Advance Research Project Agency (DARPA). The piezoelectric generators will be inserted in the soldier’s boots. The generated energy will help to operate or energy up the battlefield equipment. Although the use of the design is based on good purpose, there is

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still an effect in the body of the soldier wearing the energy generated boots or shoes. As a result, the innovation was discontinued considering the person wearing the boots experienced uneasiness or discomfort for exerting additional energy to generate more energy. 2.3.1.3.3 Gyms and Workplaces Many gym enthusiasts always help to create vibrations from the machines and equipment unknowingly. Since there are effortless number of vibrations that can be accumulated, the research workers conceptualized an idea to generate energy in an easy way. At workplaces, there are numerous ways to generate energy even if the employee is just sitting on a bench or chair. The energy generated from an employee who is sitting can be accumulated in a battery for later use by placing the piezoelectric crystals in the chair. Furthermore, the research for the vibrations gathered in several parts of a vehicle like foot rests, car seats, and clutches are being accomplished to make effective use of it. 2.3.1.3.4 Mobile Keypad and Keyboards Charging in a laptop is an efficient way when there is a limited electrical outlet but charging with the use of mobile keypad and keyboards will be more favorable. The piezoelectric crystals can be placed under the keys of a mobile keypad and

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keyboard which will cause vibration with the intention of charging an electronic device. 2.3.1.3.5 Floor Mats, Tiles and Carpets Placing a floor mats, tiles and carpets in public places can collect enormous vibration for the reason that more people are walking through the piezoelectric materials. A set of piezoelectric crystals will be placed in the flooring design like floor mats, tiles and carpets which are regularly placed in public places. 2.3.1.3.6 People Powered Dance Clubs In western places like Europe, piezoelectric crystals can be used to energy up the equipment in several nightclubs since the crystals will be placed beneath the dance floor. Great supply of voltage will generate from the dance floor from people walking or dancing through it. 2.3.1.4 Piezoelectric Energy Harvesting Piezoelectric energy harvesting floor have been implemented at Rutgers University in Busch Campus Center. The project was installed in the main highway where a high volume of people’s steps were gathered. The main goal of the project was to increase the awareness on how to gather energy from footsteps. The energy generated can supply the television displays that track the energy harvested. The energy harvested is about 7 kWh per day using about 20,000 people walking through the

27

floor tile throughout the day. The proposal of the project gave an option which are renting the floor tiles and continuing on the expansion to the other publicly areas on the New Brunswick campus. The estimated cost of the project are $50,000 for renting the floor tiles and $800,000 for the full permanent installation. The floor tiles can be installed in top of the current floor and with the use of an inverter, the generated energy can be connected to the electrical system of the building and can supply any electronics like television display. The force exerted on the floor by a person is approximately about 1 to 1.3x of the body weight. The project can harvest 50% of the energy. The area covered by the floor tiles is approximately 4,000 𝑓𝑡 2 for using 1400 tiles. The total implementation cost including the installation and maintenance cost is about $800,000. A 50-tile system can be rented because of high installation which are about $65,000 including the installation and maintenance and it can be renter over 1-3 year period. A 50-tile system can cover about 18 feet by 6 feet rectangular area. With the use of this, it can generate 173 Watts which can supply the monitoring and displaying of the harvested energy [29]. The monitoring is 5-days in a week and 15 week per semester based on the table below.

28

Figure 5. Energy Harvested of Phase 1 and Phase II This figure shows the table about energy harvested of Phase 1 and Phase 2 daily, weekly and per semester. The phase I is the rental of the tiles and the phase II is the installation of the tiles. The phase I consists of 50 piezoelectric floor tiles while the phase II consists of 1400 piezoelectric floor tiles. As shown in the results, the difference in the generated output energy of phase II to phase I in the semester calculation is 504.5 kWh. 2.3.2 Local Works and Studies 2.3.2.1 In-Wheel Piezoelectric Generator for Lighting Applications of Mining Trolleys Technology has been improving and gradually changing as years go by. Technology needs electricity for charging purposes and to energy up an equipment or a device. Piezoelectric transducer is one of the many ways on how to produce an alternative energy. A piezoelectric transducer uses a piezoelectric material like crystal. The concept in a piezoelectric crystal is to convert the mechanical energy caused by the pressure into an

29

electrical energy. Piezoelectric crystals are applicable especially in pressure that are heavy in weight. The weight coming from the wheels of the mining trolley is an ideal example for heavy weight pressure. A piezoelectric transducer is inserted to the wheels of the mining trolley to harvest energy since it always carry a very large amount of mining loads. The generated energy can be used as the energy source to light the mining trolley. The energy consumption will be reduced from energy line companies by using an enough alternative source from the piezoelectric transducer [30]. 2.3.2.2 Energy-Harnessing Footwear Using Combined Electromechanical and Piezoelectric Transducers for Charging Supercapacitors (2009) Energy harnessing footwear have been popular activating low energy devices using piezoelectric transducer. These devices acquire energy from the footsteps of the person using the shoes. This study aims to provide a new and improved energy harnessing footwear that uses not only piezoelectric transducers but a combine piezoelectric and electromechanical transducer which are both integrated in the shoes. The harvested energy will be stored and will be used to operate low energy devices such as Light Emitting Diodes and even Cellular Phone. In storing the harvested energy, an environment friendly component will be used as the energy storage. This component is a supercapacitor [31].

30

Figure 6. Energy Harvesting Shoe This figure shows the design of the Energy – Harnessing Footwear. The project used two transducers which are the piezoelectric and electromechanical transducers. These transducers are located in the shoe sole. 2.3.2.3 Power Generation for Remote Areas Utilizing Piezoelectric Transducers Harnessing Wind and Wave Energy (2011) Piezoelectric transducers are widely used as energy harvesting material. This study aims to provide simple lighting in remote areas using piezoelectric transducers as energy harvester. Wind and wave are two of the most popular sources of ambient energy. These energy are harvested using a prototype. This prototype are specifically develop to harvest and store the energy acquired and perform energy regulation techniques with the use of super capacitors and then transfer the energy to a rechargeable battery [32].

31

Chapter III Research Methodology This chapter discusses the methodology used in the study. It explains each section of the design considerations and hardware specifications of the prototype. The population and samples are also explained in this chapter. Furthermore, this chapter shows the ideal set-up of the Piezoelectric Puzzle Floor Mat. Succeeding section explains the conducted procedure and analysis to examine the appropriate output energy. This study also illustrates particular diagrams to expound how the output energy will be attained which is the main objective of this project. 3.1 Conceptual Framework

INPUT



Footsteps



Vibration

PROCESS

 Converts

OUTPUT

the

vibrations to DC



Usable DC voltage

voltage

Figure 7. Conceptual Framework This figure shows the conceptual framework of the system. The input in the project is the footsteps. Footsteps are form of mechanical energy. Vibrations are the wasted energy that comes from the human footsteps. An average person can take 3,0005,000 steps a day [2]. These footsteps came from only one person, it means that if there

32

are many people walking, there are also a higher calculation of the footsteps that can be collected per day. The project must be placed in a public place to acquire many footsteps. The generated output energy will be higher if there are many footsteps walking through the project. The main process of the project is to convert the vibrations produced by the footsteps into DC voltage. The output in this project is in the form of usable DC voltage which can be the supply voltage for some low energy applications. 3.2 Block Diagram

Footsteps

Mat Surface

Piezoelectric circuit

Full-Wave Rectifier

Step-Up Chopper

Lithium-ion Battery

Load Figure 8. Block Diagram

Wired monitoring using Energy meter or V/I meter

33

This figure shows the block diagram of the system. The human footsteps will make contact and apply pressure to the mat surface that will produce vibrations. The piezoelectric circuit converts the vibrations caused by the footstep into an AC voltage. The output AC voltage is converted to DC voltage using a full-wave bridge rectifier. The fixed DC output voltage of the rectifier will be converted into a variable DC voltage with the use of a step-up chopper and will be stored in a Lithium-ion battery. The generated voltage can be applied to a load but depending on the kind of load it can only supply. The output energy per step of the project is monitored by using an energy or V/I meter. 3.3 Schematic Diagram

Figure 9. Circuit Diagram of the System Where: X1 = 25 piezoelectric crystals connected in series D1, D2, D3, D4 = 1N4001 C1 = Electrolytic capacitors, 470µF 25V B1 = Lithium-ion battery, 3.7 VDC

34

This figure shows the circuit diagram of the project. This also shows the interconnection of the Full-Wave Bridge Rectifier, Step-Up Chopper, Lithium-ion Battery, and the Full-Wave Bridge Inverter. The voltage source of the circuit is AC voltage produced by the 25 Piezoelectric Crystals connected in series. The generated energy will be consumed by the load if there is a load. 3.3.1 Full-Wave Bridge Rectifier

Figure 10. Full-Wave Bridge Rectifier

This figure shows the Full-Wave Bridge Rectifier circuit diagram. The Full-Wave bridge rectifier converts the AC voltage source that produces by the 25 Piezoelectric Crystals connected in series into a pulsating DC. The capacitor acts as a smoothing capacitor that smooth out the pulsating DC produced by the Full-Wave Bridge Rectifier and creates ripples.

35

3.3.2 Step-Up Chopper (DC/DC converter) A Chopper is a kind of a DC/DC converter and its energy source could be a rectified A.C. or a battery. The main function of a Chopper is to convert a fixed DC source into a variable DC voltage. In the project, the input voltage of step-up chopper is the rectified output voltage of the Full-Wave Bridge Rectifier. 3.3.3 Lithium-ion Battery

Figure 11. Lithium-ion Battery This figure shows the Lithium-ion Battery which purpose is storing of the DC voltage output from the step-up chopper.

36

Table 1. Specifications of Lithium-ion Battery

Model

GEB5650122

Voltage Output

3.7V DC

Current Capacity

4000mAh

Charging Voltage

4.25V 500mAh

This table shows the specifications of Lithium-ion Battery. The output voltage of Lithium-ion battery is 3.7VDC 3.4 PCB Layout

Figure 12. PCB Layout This figure shows the PCB layout of the circuit diagram of the system and the connection of each components in the PCB.

37

3.5 Flow Chart of Process

Start

Footsteps

Is the person finish stepping on the floor mat?

Vibrations produced will be converted to AC voltage with the use of piezoelectric circuit

AC will be converted to DC using a full-wave bridge rectifier

Fixed DC voltage to variable DC voltage using a Step-up Chopper

A

Wait for the person to finish stepping on the floor mat

38

A Monitor using energy or V/I meter DC output stored in a Lithium-ion battery

DC voltage

Is there a load?

The load will consume the DC electrical energy stored in the Lithium-ion battery

End

Figure 13. System Flowchart This figure shows the system flowchart of the system. The system will start when the footsteps have made contact to the surface of the floor mat. The system will ask if the person that made contact to the floor mats’ surface is finished stepping on the floor mat. The system will wait for the person to finish stepping in the floor mat if the answer is No, it will return to the question. The system will create a loop until the question is satisfied. The vibrations produced will be converted to AC voltage with the use of piezoelectric circuit if the answer is YES. The AC output voltage from the piezoelectric

39

circuit will be converted into a DC voltage with the use of a full-wave bridge rectifier. The fixed DC voltage output of the rectifier will be converted to variable DC voltage with the use of a step-up Chopper and will be stored to a Lithium-ion battery for later use. The system will ask if there is a load connected to the circuit. The load will consume the output DC electrical energy if there is a load connected to the circuit. The energy or V/I meter are the device that will be used to monitor the energy of the mat per step. The system will standby if the floor mat stops to oscillate. 3.6 Test Population Through the data gathered from Computer Services Office (CSO), the average number of students that enter the building of FEU – Institute of Technology per day is 5,780 from November 9 to 14, 2015. The average number of students that leaves the school premises is the same as the average number of students that enter. The researchers use the exit as the location of the device so most of the students will be able to step on the mat and to avoid getting wet of the Piezoelectric Puzzle Floor Mat. Due to the inconsistency of implementing of tapping the I.D., the researchers chose the date of November 9-14 of 2015 because of the strict implementation of tapping the I.D. in the entrance. 3.7 Treatment of Data 3.7.1 Calculations for the number of trials The researchers set a standard error tolerance level of 5%. The researchers the error tolerance of 5% because it is the department standard and usually used

40

in thesis. The researchers will determine the number of samples/trials needed for the project using the Slovin’s formula:

𝑛=

𝑁 1+𝑁𝑒 2

Equation 3.7.1

Where: n = number of samples/trials N = total population e = error tolerance Computing for the number of samples using Slovin’s formula, N = 5,780

n=

5,780 1+(5,780)(0.05)2

= 374.11 ≈ 374 trials

Thus, the number of trials needed to attain the appropriate energy output of the Piezoelectric Puzzle Floor Mat through continuous testing is 374. 3.7.2 Calculation for the Tolerance

Tolerance =

Average energy output − Energy output x 100% Average energy output

41

3.8 Testing Procedure 1. Assemble and place the Piezoelectric Puzzle Floor Mats on the floor

2. Be sure that the battery is fully discharge at every first trial 3. Have only one person weighing exactly 63kg to perform the testing in order to know whether the mat acquires a constant value of energy for every trial and to have a constant force applied to the mat. The person must step on the mat in his natural/normal way of walking 4. Measure the energy per step acquired by the system using an energy or V/I meter for 374 people a day for 16 days in order to test also if the floor mat can still be functional when it is use every day and to assume that the number of average students that enter to the school premises stepped on the floor mat

days =

ave. students 5,780 = = 15.45 ≈ 16 days number of trials 374

3.9 Proposed Table for Test Results Table 2. Table for test results Day Number Trials

Energy Output per step (J/step)

1 2

Tolerance %

42

3 4 5 . . . 374 Ave.

Ave.

Average energy output for 16 days: ______________ Average percentage tolerance for 16 days: ________________ The table above shows the number of trials, the energy output in each trial, the percentage tolerance, if the battery is fully charged, the average energy output and the average percentage tolerance. The researchers will perform the testing for 16 days, therefore it will have 16 tables for each day

43

3.10 Proposed Project 3.10.1 Ideal Set up

Figure 14. Ideal Set-up: A man stepping on the floor mat This figure shows the ideal set up of the device where a man steps onto the mat. Thus, creating vibrations that will produce mechanical energy which is then converted to electrical energy. 3.10.2. Design Considerations of Puzzle Floor Mat

Figure 15. Dimensions of the Puzzle Floor Mat

44

This figure shows the dimensions of the Piezoelectric Energy Harvesting floor mat which is a 20” by 20” by 3”. The dimension of the mat was in a square shape so that the force exerted on the Puzzle Floor mat is equally distributed.

Figure 16. Top View of the Puzzle Floor Mat This figure shows the top view of the Puzzle Floor Mat which consist of male jack whose purpose is to connect the output energy of the mat to the input of the other mat and female jack whose purpose is to receive the output of the other mat and connect it to the input of the mat.

45

Figure 17. Inner Part of the Puzzle Floor Mat This figure shows the inner part of the Puzzle Floor Mat where it consists of Piezoelectric Crystals, wires, and springs. The Piezoelectric Crystals are connected in series to have a higher electrical energy. The length of the springs is 1”. The maximum weight it can handle is 36,993kg. Therefore, the capacity of the floor mat can still sustain the weight of any student as long as it does not exceed 36,993kg. To compute for the maximum weight capacity of the mat, the researchers used the formula of stress. Stress is ratio of the force to the cross-sectional area and tends to compress or shorten the material [33]. The yield strength/stress for steel is 250Mpa and the area of the project’ supports is 1.5” by 1.5”.

46

ℴ=

Force Area

m 2) s 250MPa = 2.54𝑐𝑚 2 1𝑚 2 (1.5inches)2 ( ) (100𝑐𝑚 ) 1𝑖𝑛𝑐ℎ (max 𝑤𝑒𝑖𝑔ℎ𝑡 𝑖𝑛 kg)(9.81

Max weight in kg = 36,993.11927 kg ≈ 36,993kg Table 3. Specifications of Smaller Spring

Lee Stock number (model)

LHP 098G 04S

Outside diameter

0.48” or 12.19mm

Free Length

1” or 25.40mm

Approx. Load at Solid Height

122.18 lbs or 55.421 kg

Solid Height

0.715” or 18.16mm

Max. deflection

0.285” or 7.24mm x (0.80)

Spring rate/constant

429.96 lb/in or 7.678 kg/mm

This table shows the specifications of the smaller springs. The spring’s model, outside diameter, free-length, approx. load and solid height, solid height, maximun deflection, and the spring rate/constant are shown in the table. The springs should be sturdy enough so that when a person step on the mat, it will not be deformed.

47

Table 4. Specifications of the Bigger Springs as a support Lee Stock number (model)

LHP 130J 03S

Outside diameter

0.72” or 18.29mm

Free Length

1” or 25.40mm

Approx. Load at Solid Height

165.10 lbs or 74.889 kg

Solid Height

0.705” or9mm

Max. deflection

0.295” or 7.51 mm x (0.82)

Spring rate/constant

559.80 lb/in or 9.997 kg/mm

This table shows the specifications of the bigger springs as a support. The spring’s model, oustdie diameter, free-length, approx. load and solid height, solid height, maximun deflection, and the spring rate/constant are shown in the table. The springs should be sturdy enough so that when a person step on the mat, it will not be deformed.

48

(a.)

(b.) Figure 18. Comparison of design with respect to vibrations This figure shows the comparison of design of existing study with the researchers’ study with respect to vibrations. Figure a shows the design of an existing study of Piezoelectric floor tile which has four springs as a support to the floor tile. While figure b shows the design of current study which has a total of 29 springs as a support to the floor mat. Figure b can produce larger and longer vibrations since it has the more number of springs. Moreover, the location of the spring of figure b is just below the floor mat unlike figure a. Thus, the effect of the steps is directly to the springs. The more number of springs, the less its tendency of going sideways.

49

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2015.

[Online].

[6] "SparkNotes," SparkNotes LLC, 2015. [Online]. http://www.sparknotes.com/physics/oscillations/review/terms.html.

Available:

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[7] I. Poole, "Radio-Electronics.com," Adrio Communications Ltd, [Online]. Available: http://www.radio-electronics.com/info/circuits/opamp_basics/operational-amplifiergain.php. [8] "CSGNetwork," Copyscape, http://www.csgnetwork.com/ohmslaw2.html.

[Online].

[9] "Index Mundi," Index Mundi, 30 June 2015. [Online]. (http://www.indexmundi.com/philippines/electricity_consumption.html.

Available:

Available:

[1 "eBay," eBay, March 2014. [Online]. Available: http://www.ebay.com/gds/What-is-the0] Difference-Between-Floor-Mats-and-Floor-Liners-/10000000177404865/g.html. [1 J. Lewitin, "About Home," About.com, [Online]. Available: 1] http://flooring.about.com/od/Flooring-Pros-And-Cons/a/Rubber-Flooring-Tiles-The-PriceOf-Durability.htm. [1 "NDT Resource Center," 2009. [Online]. Available: https://www.nde2] ed.org/EducationResources/CommunityCollege/Ultrasonics/EquipmentTrans/piezotransd ucers.htm. [1 S. Ankur and T. Pramathesh, "Piezoelectric Crystals : Future Source of Electricity," 3] International Journal of Scientific Engineering and Technology, vol. II, no. 4, pp. 260-262, 2013.

50 [1 M. Oswal, J. Paul and R. Zhao, "A Comparative Study of Lithium - Ion Batteries," University 4] of Southern California, California. [1 T. L. Floyd, Electronics Devices, New Jersey: Prentice Hall, 2012. 5] [1 "electrical4u.com," electrical4u, [Online]. Available: 6] http://www.electrical4u.com/chopper-dc-to-dc-converter/. [Accessed October 2015]. [1 "Springs and Things Inc," Spring Manufacturers Institute, [Online]. Available: 7] http://www.springsandthings.com/pdf/Compression-new.pdf. [Accessed October 2015]. [1 "Energy Harvesting Forum," www.energyharvesting.net, 8] http://www.energyharvesting.net/. [Accessed 6 October 2015].

[Online].

[1 "Mtholyoke," Mtholyoke.edu, [Online]. 9] http://www.mtholyoke.edu/~walch20l/classweb/wp/prosandcons.html. October 2015].

Available:

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[2 C. Woodford, "Explain that Stuff!," 2009. [Online]. Available: 0] http://www.explainthatstuff.com/piezoelectricity.html. [Accessed 6 October 2015]. [2 "Nanomotion," Johnson Electric, [Online]. Available: http://www.nanomotion.com/piezo1] ceramic-motor-technology/piezoelectric-effect/. [Accessed 6 October 2015]. [2 C. Woodford, "Piezoelectricity," 2009. 2] http://www.explainthatstuff.com/piezoelectricity.html.

[Online].

Available:

[2 "electrical4u.com," electrical4u, 2011. [Online]. Available: 3] http://www.electrical4u.com/ohms-law-equation-formula-and-limitation-of-ohms-law/. [2 T. Cox, "Simple Harmonic Motion," University of Salford, Manchester. 4] [2 J. K. Roberge, "Operational Amplifiers: Theory and Practice," John Wiley & Sons Inc., 5] Massachusetts, 1975. [2 J. Ryall, "Japan harnesses energy from footsteps," The Telegraph, 12 December 2008. 6] [2 J. Zhao and Z. You, "A Shoe-Embedded Piezoelectric Energy Harvester for Wearable 7] Sensors," National Center for Biotechnology Information, 2014. [2 T. Dikshit, D. Shrivastava, G. Abhijeet, A. Gupta, P. Parandkar and S. Katiyal, "Energy 8] Harvesting via Piezoelectricity," BIJIT - BVICAM’s International Journal of Information Technology, vol. II, 2010.

51 [2 B. Doyle, "Piezoelectric Energy Harvesting," p. 9, 2012. 9] [3 J. L. T. Besinio, N. A. D. Bustamante, M. J. V. Nicolas, A. S. Tolentino and P. G. T. Valbuena, 0] "In-Wheel Piezoelectric Generator For Lighting Applications of Mining Trolleys," De La Salle University , 2011. [3 L. E. F. Altarejos, E. J. R. Apuli, M. E. G. Dela Cruz, A. J. G. Gamilla and S. R. L. Garcia, "Energy1] Harnessing Footware Using Combined Electromechanical And Piezoelectric Transducers for Charging Supercapacitors," De La Salle University, 2009. [3 J. C. M. Hung, M. H. A. Rilles and K. B. Monillas, "Power Generation For Remote Areas 2] Utilizing Piezoelectric Transducers Harnessing Wind And Wave Energy," De La Salle University, 2011. [3 "The Engineering Toolbox," [Online]. 3] http://www.engineeringtoolbox.com/stress-strain-d_950.html.

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[3 "BBC," BBC, 2014. [Online]. Available: 4] http://www.bbc.co.uk/schools/gcsebitesize/science/edexcel/generation_transmission_el ectricity/electrical_quantitiesrev3.shtml. [3 B. Doyle, Piezoelectric Energy Harvesting, p. 9, May 2012. 5] [3 T. Caston, "Piezoelecctric Energy Harvesting Floor Mat," Electrical Engineering Community, 6] EEWEB, 2011. [3 L. Gittins, "Houstin Chronicle," Hearst Newspaper, LLC, [Online]. 7] http://smallbusiness.chron.com/types-bluetooth-technology-58388.html.

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[3 N. Ismail and R. Abd Ghani, "Advance Devices Using Piezoelectric Harvesting Energy," IEEE 8] Xplore Digital Library, pp. 450 - 453, 2013. [3 J. Carrillo and D. Marusiak, "Energy Harvesting of Human Movement," California 9] Polytechnic State University , 2012. [4 "Star Trek," startrek.com, 2015. [Online]. Available: http://stattrek.com/chi-square0] test/independence.aspx?Tutorial=AP. [4 M. S. N. N. G. Monika Jain, ""VIDYUT Generation via Walking: Analysis"," International 1] Journal of Engineering Sciences and Resaerch Technology , Feb 2013.

52

APPENDIX A Chi-Square Critical Values Table

Degrees of

Probability of Exceeding the Critical Value

Freedom 0.10

0.05

0.025

0.01

1

2.706

3.841

5.024

6.635

2

4.605

5.991

7.378

9.210

3

6.251

7.815

9.348

11.345

4

7.779

9.488

11.143

13.277

5

9.236

11.070

12.833

15.086

6

10.645

12.592

14.449

16.812

7

12.017

14.067

16.013

18.475

8

13.362

15.507

17.535

20.090

9

14.684

16.919

19.023

21.666

53

10

15.987

18.307

20.483

23.209

11

17.275

19.675

21.920

24.725

12

18.549

21.026

23.337

26.217

13

19.812

22.362

24.736

27.688

14

21.064

23.685

26.119

29.141

15

22.307

24.996

27.488

30.578

16

23.542

26.296

28.845

32.

17

24.769

27.587

30.191

33.409

18

25.989

28.869

31.526

34.805

19

27.204

30.144

32.852

36.191

20

28.412

31.41

34.17

37.566

54

APPENDIX B Bill of Materials The tabulated estimation cost of the materials that are needed for the construction of the project are listed below: No. Materials

Price

Quantity

Total Price

1

Piezoelectric Buzzer/Transducer

50.00

25

1250.0

2

Puzzle Rubber Sheets

500.00

10

5,000.00

2,500.00

1

2,500.00

80.00

8

640.00

(20in x 20in x 3in) 3

Stainless Steel (15in x 1in x 1in)

4 5

Vinyl Tile

Banana Jacks (Female) and 150.00 Plug (Male) 150.00

4 pairs (8 pieces) Banana Jacks 1,200.00 4 pairs (8 pieces) Banana Plugs

6

Small Compression Spring

75.00/pack

100

150.00

7

Big Compression Spring

80.00/pack

20

80.00

8

Diodes

10.00

20

200.00

6.00

2

12.00

(1N4001) 9

Capacitors (470uF, 25V)

10

Chopper

1,000.00

1

1,000.00

11

Energy meter

5,000.00

1

5,000.00

12

Lithium (3.7V)

1

575.00

13

PCB and Developer

90.00

4

360.00

14

Ferric Chloride

40

1

40.00

TOTAL

–

ion

Battery 575.00

18,007.00

55

APPENDIX C Gantt Chart This table provides the chart illustration of the researcher’s Project Study 1 schedule which enables the researchers to coordinate and track specific activities and tasks.

56

APPENDIX D Average Weight of Students in FEU-Institute of Technology

57

58

59

60

APPENDIX E Data of Average Students that Entered the School Premises

Date

Number of Students that Entered the School Premises

2015-08-25

744

2015-08-26

6,075

2015-08-28

6,288

2015-08-29

4,834

2015-09-01

5,715

2015-09-02

4,352

2015-09-03

5,484

2015-09-04

5,412

2015-09-05

4,066

2015-09-07

4,882

61

2015-09-08

5,335

2015-09-09

4,620

2015-09-10

4,673

2015-09-11

2,445

2015-09-12

3,535

2015-09-14

4,875

2015-09-15

4,891

2015-09-16

4,016

2015-09-17

4,038

2015-09-18

3,948

2015-09-19

2,466

2015-09-21

3,628

2015-09-22

3,180

2015-09-23

3,614

2015-09-24

3,587

2015-09-26

2,750

2015-09-28

3,704

2015-09-29

2,389

2015-09-30

1,556

62

2015-09-30

1,556

2015-10-01

3,215

2015-10-03

2828

2015-10-05

2,320

2015-10-06

2,377

2015-10-07

1,684

2015-10-08

1,789

2015-10-09

1,691

2015-10-10

1,565

2015-10-12

1,401

2015-10-13

1,040

2015-10-14

522

2015-10-15

837

2015-10-16

4,030

2015-10-17

4,073

2015-10-20

4,256

2015-10-21

3,502

2015-10-22

2,080

2015-10-23

3,794

63

2015-10-24

345

2015-10-26

1,334

2015-10-27

3,987

2015-10-28

2,793

2015-10-29

1,656

2015-10-30

1,678

2015-11-02

5,816

2015-11-03

5,953

2015-11-04

6,445

2015-11-05

8,109

2015-11-06

7,158

2015-11-07

5,123

2015-11-09

7,103

2015-11-10

6,698

2015-11-11

5,430

2015-11-12

6,048

2015-11-13

5,672

2015-11-14

3,729

APPENDIX F CONSULTATION SHEET Project Study 1

Members: CAPATI, Aubrey Sharmaine M. MAGLUYAN, Pamela Kim Donnelle G. POSTRE, Raul Christian M.

Engr. Luigi Carlo M. De Jesus Adviser

DATE

TIME

ACTIVITY

08 – 20 – 15

18:00 – 19:00

Chapter __ : Consultation

08 – 24 – 15

14:30 – 15:00

Chapter __ : Consultation

08 – 27 – 15

16:00 – 16:30

Chapter __ : Consultation

09 – 02 – 15

13:30 – 14:00

Chapter __ : Consultation

09 – 06 – 15

12:30 – 14:00

Chapter __ : Consultation

09 – 07 – 15

16:10 – 17:35

Chapter __ : Consultation

09 – 10 – 15

15:40 – 16:00

Chapter __ : Consultation

09 – 11 – 15

16:40 – 16:55

Chapter __ : Consultation

SIGNATURE

09 – 16 – 15

13:45 – 15:00

Chapter __ : Consultation

09 – 21 – 15

13:10 – 13:30

Chapter __ : Consultation

09 – 22 – 15

13:50 – 14:30

Chapter __ : Consultation

09 – 24 – 15

13:10 – 13:50

Chapter __ : Consultation

09 – 30 – 15

10:42 – 11:05

Chapter __ : Consultation

10 – 03 – 15

12:40 – 13:15

Chapter __ : Consultation

10 – 08 – 15

13:40 – 14:35

Chapter __ : Consultation

10 – 12 – 15

13:15 – 14:10

Chapter __ : Consultation