Piezo-Electrocity & Voltage Measurement

PIEZO-ELECTRICITY & VOLTAGE MEASUREMENT

Abstract 

This project will demonstrate the theory and working of piezoelectric material. When some pressure is applied on piezoelectric transducer small amount of potential difference is produced in transducer.

Piezoelectricity is the ability of some materials to generate an electric field or electric potential in response to applied mechanical strain. The effect is closely related to a change of polarization density within the material's volume. If the material is not short-circuited, the applied stress/strain induces a voltage across the material. 

Piezoelectric materials are commonly used to produce small amount of  currents for this piezoelectric transducer is used. Transduce is a simple device that converts small amounts of enerfy from one kind to another. Here mechanical energy is converted in to electrical energy.

In the society this instrument is used to produce electricity in small quantities(example charging mobile, used in touch screen mobiles).

CONTENTS

                                               

1.                  INTRODUCTION

1.1 Need of the project                                                                                                          

1.2 Scheme of the project                                                                                                      

1.3 Basic circuit/components required                                                                                   

2.   LITERATURE REVIEW

2.1 Types of techniques already held                                                                                    

3.  IMPLEMENTATION/DESIGN/DEVELOPMENT/PROGRAMMING

                                   

3.1 Procedures/ operation of the project                                                                                

                                                                                                                                               

4.   RESULTS & ANALYSIS

4.1 Tables

4.2 Graphs

5.   CONCLUSION                                                                                                  

6.  REFERENCES                                                                                                               

1. INTRODUCTION:

Piezoelectricity is the electric charge    that accumulates in certain solid materials (such as crystals, certain ceramics) in response to applied mechanical stress.piezoelectricity means electricity resulting from pressure.In order to run an electric load (such as a light bulb) on a piezoelectric device, the applied mechanical stress must oscillate back and forth.

PIEZO ELECTRIC MATERIALS: The materials which convert mechanical energy to electrical energy are called piezo electric materials. Examples: Quartz, Rochelle salt, cane sugar, etc.

PIEZO ELECTRIC EFFECT: This effect was first demonstrated by Pierre curie and Jacques curie. According to this effect due to the pressure the electricity is produced. When pressure is applied on piezoelectric material then mechanical energy is converted into electrical energy. This production of electrical energy is called as piezo electric effect.

PIEZO ELECTRICITY: The electricity produced due to the piezo electric effect is called as piezo electricity.

PEIZOELECTRIC TRANSDUCER:

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.

Components required :

Piezo-electric Transducers, Connecting wires, Multimeter, Soldering kit.

2.      LITERATURE REVIEW :

• Voltage procuded is measured by voltmeter.
• Voltage can be tested by connecting piezomaterial to arduino and results can be seen on screen.

3.      IMPLEMENTATION:

3.1 Builting circuit:

Circuit System Requirements:

·        Multimeter

·        Piezo-eletric transducer

·        Connecting wires

·        Soldering kit

Circuit Working:

To a piezo electric sensor a diode is connected in series to allow the flow of current in only in one direction. To this 1KΩ resistor is connected .to this a capacitor of 500µf is connected in parallel so as to store current that is generated from piezo electric sensor .the whole system is now connected to LED lights .a switch is connected to the circuit to control the flow of current. When the pressure or stress is applied to the piezo electric sensor, current is passed through the diode and some amount of charge is stored in the capacitor for further uses .actually connecting a capacitor in parallel gives us more current than connecting it in series. To measure the current in the circuit a multimeter is connected and the values are recorded and a LED light is connected to the circuit so that it glows as the currents passes through it.

4. Results:

S no.	Mass (gm)	Force (dyne)	Pressure (dyne/cm2)	Voltage (V)
1	100 gm	981	281.89	0.21
2	200 gm	1962	563.79	0.33
3	300 gm	2943	845.68	0.58

Radius = 0.95 cm

Area = 3.48 cm²

^Graph:

5.   CONCLUSION                                                                                                  

From this project we have concluded that by increase in pressure the output voltage from piezoelectric material is increased.

Galvanic Cell Construction

CONTENTS

1. Introduction

2. Aim and objectives

3. Methodology

4. Results and discussion

5. Conclusion

1. Introduction:

A galvanic cell, named after Luigi Galvani, is an electrochemical cell that derives electrical energy from spontaneous redox reactions taking place within the cell. It generally consists of two different metals connected by a salt bridge, or individual half-cells separated by a porous membrane.

Volta was the inventor of the voltaic pile, the first electrical battery. In common usage, the word "battery" has come to include a single galvanic cell, but a battery properly consists of multiple cells.

In its simplest form, a half-cell consists of a solid metal (called an electrode) that is submerged in a solution; the solution contains cations of the electrode metal and anions to balance the charge of the cations. In essence, a half-cell contains a metal in two oxidation states; inside an isolated half-cell, there is an oxidation-reduction (redox) reaction that is in chemical equilibrium, a condition written symbolically as follows:

Mⁿ⁺ (oxidized) + ne⁻ ⇌ M (reduced)

A galvanic cell consists of two half-cells, such that the electrode of one half-cell is composed of metal A, and the electrode of the other half-cell is composed of metal B; the redox reactions for the two separate half-cells are thus:

Aⁿ⁺ + ne⁻ ⇌ A

B^m+ + me⁻ ⇌ B

In general, then, these two metals can react with each other:

m A + n B^m+ ⇌ n B + m Aⁿ⁺

2.  Aim and objectives:

Fabrication of salt bridge and construction of galvanic cell for Cu & Zn.

3. Methodology:

Take a 500ml beaker and full it with 250ml of 1M CuSO₄. In another 500ml beaker full 250ml of 1M ZnSO_4. In the beaker containing CuSO₄ immerse copper plate and in beaker containing ZnSO₄ immerse zinc plate. Now prepare a salt bridge to create a medium between solutions. Take few amount of NaCl and dissolve it in water. Soak a cloth in NaCl solution. Connect the half cells by salt bridge. When multimeter is connected in between Zinc and Copper plate some potential difference is observed.

Zinc Half Cell:

The anode(Zinc) is the electrode where oxidation (loss of electrons) takes place; in a galvanic cell, it is the negative electrode, as when oxidation occurs, electrons are left behind on the electrode. These electrons then migrate to the cathode (positive electrode). However, in electrolysis, an electric current stimulates electron flow in the opposite direction. Thus, the anode is positive, The zinc electrode is the anode.

Zn à Zn²⁺ + 2e^-

Copper Half Cell:

The cathode(copper) is the electrode where reduction (gain of electrons) takes place; in a galvanic cell, it is the positive electrode, as less oxidation occurs, fewer ions go into solution, and less electrons are left on the electrode. Instead, there is a greater tendency for aqueous ions to be reduced by the incoming electrons from the anode. However, in electrolysis, the cathode is the negative terminal, and attracting positive ions from the solution. The copper electrode is the cathode.

Cu²⁺ + 2e^- à Cu

Copper readily oxidizes zinc; for the Galvanic cell depicted in the figure, the anode is zinc and the cathode is copper, and the anions in the solutions are sulphates of the respective metals. When an electrically conducting device connects the electrodes, the electrochemical reaction is:

Zn + Cu²⁺ → Zn²⁺+ Cu

The zinc electrode is dissolved and copper is deposited on the copper electrode.

Galvanic cells are typically used as a source of electrical power. By their nature, they produce direct current.

4. Results and discussion:

The obtained results of Galvanic cell are given in table below with different concentrations of Solutions.

Concentration of CuSO4	Concentration of ZnSO4	Voltage Obtained
1M CuSO4	1M ZnSO4	1.08V
0.01M CuSO4	0.01M ZnSO4	0.81V
0.01M CuSO4	1M ZnSO4	0.7V
1M CuSO4	0.01M ZnSO4	1.01V

According to the theoretically calculated valve the maximum obtained voltage for 1M CuSO₄ and 1M ZnSO₄ should be 1.1V. But in our project we got a maximum voltage of 1.08V this may be due to some impurities present in solutions and corrosion of zinc and copper plates.

5. Conclusion:

By this project we became familiar with various concepts such as solutions by way of dissolved ions. We have observed redox reactions at work, and that they can be 

Piezo-Electric Generator

AIM:

Electricity generation using piezo-electric material by footfall pressure

INTRODUCTION:

The increasing desire for completely self-powered electronics has caused the amount of research into power harvesting devices to become progressively larger over the last decade. With the advances being made in wireless technology and low power electronics, sensor are being developed that can be placed almost anywhere. However, because these sensors are wireless, they require their own power supply which in most cases is the conventional electrochemical battery. Once these finite power supplies are extinguished of their power, the sensor must be obtained and the battery replaced. The task of replacing the battery is tedious and can become very expensive when the sensor is placed in a remote location. These issues can be potentially alleviated through the use of power harvesting devices. The goal of a power harvesting device is to capture the normally lost energy surrounding a system and convert it into usable energy for the electrical device to consume. By utilizing these untapped energy sources electronics that do not depend on finite power supplies, such as the battery, can be developed. One source of typically lost energy is the ambient vibrations present around most machines and biological systems. This source of energy is ideal for the use of piezoelectric materials, which have the ability to convert mechanical strain energy into electrical energy and vice versa. As compact, low power electronics become more prevalent in everyday use and as their increasing portability requires reliable power sources, ambient energy harvesting devices show much potential over batteries. Indeed, by relying on energy scavenged from the environment, such electronics are no longer restricted by the periodic maintenance that batteries demand. In particular, energy harvested parasitically from human movements has garnered much discussion. Perhaps the most energy abundant and readily utilized form of ambient human power is walking. The project aims at developing a shoe embedded with piezoelectric material (PVDF) into a wearable energy supplier.

PIEZOELECTRIC CRYSTAL:

Piezoelectricity is the ability of some materials (notably crystals, certain ceramics, and biological matter such as bone, DNA and various proteins) to generate an electric field or electric potential in response to applied mechanical strain. The effect is closely related to a change of polarization density within the material's volume. If the material is not short-circuited, the applied stress/strain induces a voltage across the material. However, if the circuit is closed the energy will be quickly released. So in order to run an electric load (such as a light bulb) on a piezoelectric device, the applied mechanical stress must oscillate back and forth. For example, if you had such a device in your shoes you could charge your cell phone while walking but not while standing.

PIEZO ELECTRIC MATERIALS: The materials which convert mechanical energy to electrical energy are called piezo electric materials. Examples: Quartz, Rochelle salt, cane sugar, etc.

PIEZO ELECTRIC EFFECT: This effect was first demonstrated by Pierre curie and Jacques curie. According to this effect due to the pressure the electricity is produced. When pressure is applied on piezoelectric material then mechanical energy is converted into electrical energy. This production of electrical energy is called as piezo electric effect.

PIEZO ELECTRICITY: The electricity produced due to the piezo electric effect is called as piezo electricity.

FOOTFALL PRESSURE: The pressure produced by the footfall on the ground is called is footfall pressure.

MECHANISM:

The nature of the piezoelectric effect is closely related to the occurrence of electric dipole moments in solids. The latter may either be induced for ions on crystal lattice sites with asymmetric charge surroundings (as in BaTiO₃ and PZTs) or may directly be carried by molecular groups. The dipole density or polarization may easily be calculated for crystals by summing up the dipole moments per volume of the crystallographic unit cell. As every dipole is a vector, the dipole density P is also a vector or a directed quantity. Dipoles near each other tend to be aligned in regions called Weiss domains. The domains are usually randomly oriented, but can be aligned during poling, a process by which a strong electric field is applied across the material, usually at elevated temperatures.

Of decisive importance for the piezoelectric effect is the change of polarization P when applying a mechanical stress. This might either be caused by a re-configuration of the dipole-inducing surrounding or by re-orientation of molecular dipole moments under the influence of the external stress. Piezoelectricity may then manifest in a variation of the polarization strength, its direction or both, with the details depending on

1. The orientation of  P within the crystal.

2. Crystal symmetry.

3. The applied mechanical stress.

Working Methodology:

For energy generation through piezoelectricity piezoelectric crystals made of PZT are arranged in a grid on the floor the unique piezoelectric and converse piezoelectric properties of crystalline PZT allow us to design an electro-mechanical device. By operating the device at its mechanical resonance frequency, we can get a useful electrical output out of it. The active element is the heart of the transducer as it converts the stress due to weight to electricity. The active element is basically a piece of polarized material (i.e. some parts of the molecule are positively charged, while other parts of the molecule are negatively charged) with electrodes attached to two of opposite faces. As the major aim of making the Electricity generating floor is to utilize the stress from to human foot fall and generate electricity the mechanical stress due to human weight is considered as the input power and the electricity generated through it is the output.

To create electricity, the EGF will compress up to 1mm when being stepped on. Because of the air gap and one free end of the piezo crystal it will be able to vibrate freely when stress is released. As a result efficient power generation occurs. This small compression is enough to activate the internal generator of that module producing up to 5 -7 Watts of sustained output per module. This system allows for the floor to be set up in a huge range of possible sizes, shapes and designs.

Circuit System Requirements:

·        PCB board

·        LED lights

·        Multimeter

·        Piezo-eletric transducer

·        Connecting wires

·        Switch

·        500 μf capacitor

·        100 ohm resistor

·        Soldering kit

Circuit Working:

To a piezo electric sensor a diode is connected in series to allow the flow of current in only in one direction. To this 1KΩ resistor is connected .to this a capacitor of 500µf is connected in parallel so as to store current that is generated from piezo electric sensor .the whole system is now connected to LED lights .a switch is connected to the circuit to control the flow of current. When the pressure or stress is applied to the piezo electric sensor, current is passed through the diode and some amount of charge is stored in the capacitor for further uses .actually connecting a capacitor in parallel gives us more current than connecting it in series. To measure the current in the circuit a multimeter is connected and the values are recorded and a LED light is connected to the circuit so that it glows as the currents passes through it.

APPLICATIONS:

This electricity generating floor can be installed in the places where there will be a lot floating of population.

1.     Railway stations: These will be always busy with passengers. (Fig 1)

2.     Dance clubs: This is the most important place because there will be a lot of pressure is produced. This current produced is used for sound systems.

3.     Foot wears soles equipped with piezoelectric pads. (Fig 2)

4.     Gym machinery: On the gym machinery like thread wheels these can be arranged to produce current which can be used in music system.

5.     Footpaths: As all the pedestrians are compulsory to walk on the footpaths this will be more use full.

6.     Roads: As heavy vehicles move more pressure is applied on piezoelectric material and this can produce large amount of current which can be used for traffic display boards

7.     Shopping mall: There will be a lot of customers always visiting.

8.     Railway stations: These will be always busy with passengers.

by
N.Nikhil
M.Gopi Reddy
P.Mahati Aditya