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  3. 3. PIEZOELECTRIC MATERIAL: 5.1 Power Walking With Energy Floors 5.2 Piezoelectric road harvests traffic energy to generate electricity 5.3 Public Areas Chapter 6: RESULTS & CONCLUSION Chapter 7: REFERENCES 3
  4. 4. 1 INTRODUCTION 1.1 OBJECTIVE Our main aim is to produce light out of the force or stress applied on the piezoelectric sensor. This can solve many problems regarding the dependency on the replenishing sources of energy, by harvesting energy, since the world is in need of energy. This produced light could be the solution for: 1. Growing need for renewable sources of energy, 2. Reduce dependency on battery power, 3. Lights can be used in automobiles, footwear, etc.. Today, the energy harvesting from light, thermal, magnetic or mechanical energy in the ambient environment is an important research topic. With recent progresses in wireless, sensor systems are being popularly used in various areas, including human body care, bridge or engine early health monitoring etc. . However, replacement of small power supplies and batteries in sensor systems would be a tedious task. Therefore, it is quite interesting to supply a small amount of power for sensor systems from environmental energy. In addition, because of the shortage in energy sources, people are also seeking environmental energy to replace part of the electric energy used in daily life. Therefore, another interesting application is to harvest the mechanical energy from highway or railway for generating electric energy, which may supply a small to medium amount of power for powering road lights or even electric motors if there are enough vehicles/trains running. One of the most effective methods for power harvesting systems is to use piezoelectric materials to convert mechanical vibration or strain energy to electric energy based on the piezoelectric effect. During the past ten years, there has been an 4
  5. 5. explosion of research in the area of harvesting energy from ambient vibrations by using the direct piezoelectric effect. Piezoelectric materials are very good prospects for mechanical energy conversion because they have a good electromechanical coupling effect. Piezoelectric energy harvesting devices are also much simpler than, for example electromagnetic or electrostatic devices. For these reasons, piezoelectric energy harvesting devices have attracted much attention. Conventional piezoelectric harvesting devices are based on a piezoelectric unimorph or bimorph cantilever configuration i.e., one or two piezoelectric elements laminated with one long elastic plate, and they are operated in bending mode. In general, piezoelectric cantilever type harvesters generate only a very small power output, and they cannot work under pressure. In 2004, Uchino’s group at Pennsylvania State University developed a piezoelectric cymbal transducer which operated in flextensional mode for vibration energy harvesting, which could work well under a small force load. 1.2 PIEZOELECTRIC EFFECT There are certain materials that generate electric potential or voltage when mechanical strain is applied to them, they tend to change their dimensions. This is called piezo electric effect. This effect was discovered in the year 1880 by Pierre and Jacques Curie. The piezoelectric transducers work on the principle of piezoelectric effect. When mechanical stress or forces are applied to some materials along certain planes, they produce electric voltage. The voltage output obtained from these materials due to piezoelectric effect is proportional to the applied stress or force. 5
  6. 6. 1.3 NEED OF ENERGY HARVESTING • Growing need for renewable sources of energy • Proposes several potentially inexpensive and highly effective solutions • Reduce dependency on battery power • Complexity of wiring • Increased costs of wiring • Reduced costs of embedded intelligence • Increasing popularity of wireless networks • Limitations of batteries • Reduce environmental impact 1.4 PIEZOELECTRIC MATERIAL (Material with Piezo properties): 1.4.1 Naturally occurring crystals: Berlinite (AlPO4), Cane sugar, Quartz, Rochelle salt, Topaz, Tourmaline Group Minerals, and dry bone (apatite crystals) 1.4.2 Man-made ceramics: Barium titanate (BaTiO3), Lead titanate (PbTiO3), Lead zirconate titanate (Pb[ZrxTi1-x]O3 0<x<1) - More commonly known as PZT, Potassium niobate (KNbO3), Lithium niobate (LiNbO3), Lithium tantalate (LiTaO3), Sodium tungstate (NaxWO3), Ba2NaNb5O5, Pb2KNb5O15 1.4.3 Polymer: Polyvinyledene fluoride (PVDF) 6
  7. 7. 2 LITERATURE SURVEY 2.1 PYROELECTRIC EFFECT When the temperature of the material is changed, an electric potential appears between the terminals: this is called the pyroelectric effect. 2.2 PIEZOELECTRIC FILMS Piezoelectricity can be obtained by orienting the molecular dipoles of polar polymers such as PVDF in the same direction by subjecting films to an intense electric filed: this is the polarization. The polarized electrets are thermodynamically stable up to about 90°C. PVDF is particularly suitable for the manufacture of such polarized films because of its molecular structure (polar material), its purity – which makes it possible to produce thin and regular films – and its ability to solidify in the crystalline form for polarization. 2.3 PROPERTIES OF PVDF PIEZOELECTRIC FILMS Flexibility (possibility of application on curved surfaces) High mechanical strength Dimensional stability High and stable piezoelectric coefficients over time up to approximately 90°C Characteristic chemical inertness of PVDF Continuous polarization for great lengths spooled onto drums Thickness between 9 microns and 1 mm. 2.4 COMPONENTS USED Piezo electric cells. Sensors Actuators One aluminium metal sheet. LED,s DC converter Amplifier Wires Piezo Electric Cells 7
  8. 8. 2.4.1 Piezoelectric Cell The piezoelectric cell is what allows us to convert the mechanical energy to electrical energy thus, utilizing our wasted energy. The piezoelectric inputs the energy from the input signal and outputs the signal to our circuit system. We will buy this component as it is too physically advanced for us to construct and we do not have the tools to construct it. Fig 2.1 2.4.2 Sensors The principle of operation of a piezoelectric sensor is that a physical dimension, transformed into a force, acts on two opposing faces of the sensing element. Depending on the design of a sensor, different "modes" to load the piezoelectric element can be used: longitudinal, transversal and shear Detection of pressure variations in the form of sound is the most common sensor application, e.g. piezoelectric microphones (sound waves bend the piezoelectric material, creating a changing voltage) and piezoelectric pickups for Acousticelectric guitars. A piezo sensor attached to the body of an instrument is known as a microphone. Piezoelectric sensors especially are used with high frequency sound in ultrasonic transducers for medical imaging and also industrial nondestructive testing (NDT). 8
  9. 9. Fig 2.2 2.4.3 Actuators As very high electric fields correspond to only tiny changes in the width of the crystal, this width can be changed with better-than-μm precision, making piezo crystals the most important tool for positioning objects with extreme accuracy — thus their use in actuators. Multilayer ceramics, using layers thinner than 100 μm, allow reaching high electric fields with voltage lower than 150 V. These ceramics are used within two kinds of actuators: direct piezo actuators and Amplified piezoelectric actuators. While direct actuator's stroke is generally lower than 100 μm, amplified piezo actuators can reach millimeter strokes. 2.4.4 DC Converter Our converter, an AC/DC converter, inputs an AC source and outputs a DC source. We need a DC source because if we decide to power an energy storage device we will need to provide that with a DC source. Our AC/DC converter is built from a bridge rectifier type schematic (see schematic) since an AC/DC IC was not available. This block is also responsible for protecting our circuit from reverse currents, through the use of diodes. This block receives its signal from the piezoelectric. However, there is a lot of communication within the block as this is where the real circuitry that runs our system is built. It is at this block that we no longer have mechanical energy, but electrical energy, which is output to whatever our output may be, whether an LED sign or energy storage device. 9
  10. 10. 2.4.5 Amplifier Here we amplify the current since we are expecting it to be very small. . Since we have a capacitor bank this dissipation will last longer than if we simply had a direct connection to our converter and amplifier. Thus, our LEDs, or whatever our output source is, will have power supplied for a long period of time. We can also test the efficiency of our energy storage by simply monitoring the time that the output device runs for to see whether or not our storage elements actually behaves the way we expect it to and prolongs the ―ON‖ period of our LEDs longer than if the LEDs, or other output Storing and amplifying our energy can be achieved with a circuit that contains capacitors and an op-amp. We may also use a few super capacitors; however we feel that the best approach will be a capacitor bank. We will need to test the components to find out which chips are suitable with our circuit since we need capacitors that are properly rated for our system requirements. We will test this by measuring our power usage with PSPICE simulations as well as direct measurements from our piezoelectric rods to see the voltage produced. Combining this information we will have an exact idea of what value of capacitors we will need to use in our capacitor bank. Our capacitor bank will be a certain number of capacitors connected in parallel. Fig 2.3 Each capacitor will take in a small amount of current at a time, this is distributed amongst the capacitors fairly evenly, although not exact since no capacitor has the exact same value. Then our output device, the LEDs will be powered by the current dissipating from our capacitors device, was connected straight to our converter and amplifier. Our 10
  11. 11. amplifier is very simple. Its purpose is to amplify the current, thus also reducing the voltage, so that we have more power at our output since we need a higher current to drive any device than the current we get directly from the piezoelectric rods. We can test our energy device as mentioned above and we can test our amplifier through simulating it in PSPICE to see what the best resistor combination would be to give us the right current for our output. 2.5 PIEZOELECTRIC TECHNOLOGIES According to How Stuff Works, piezoelectric materials create a positive and a negative End when work is done to deform their original shape. The International Harvest Tribune Claims that ―energy harvesting‖, more commonly referred to as ―crowd farming‖, has been in Existence for as long as 10 years. An electrical charge flows across the material once pressure is relieved from them. While they usually provide very low currents, they can generate extremely high voltages. Harvesting energy from piezoelectric flooring is said to be impractical in residential applications due to the high cost of implementation and small amount of electricity generated in these settings. Common piezoelectric materials include quartz, Rochelle salt, and some ceramics. The New York Times also claims that harvesting energy from piezoelectric materials is inefficient, converting only a small amount of kinetic energy into electricity. The Christian Science Monitor claims that a single footstep could potentially generate enough electricity to power two 60-watt incandescent bulbs for one second, while the International Herald Tribune claims that the technology were implemented in a busy train station that the energy captured could power 6,500 LED lights for an unspecified amount of time. 2.6 LED TECHNOLOGY Light-emitting diodes, or LEDs, show promise for replacing traditional lighting sources. According to the Christian Science Monitor, the European Union has banned the sale of incandescent light bulbs because of their inefficiencies, with BBC News stating that Australia has followed suit and banned them as well. Specifically, they cite that the standard incandescent light bulb converts only about five percent of the electricity it uses into usable 11
  12. 12. light, with the rest being converted into heat. LEDs are approximately four times more efficient than incandescent light bulbs and currently as efficient as fluorescent lighting without the environmentally harmful mercury content that they contain according to Purdue University. LEDs also carry the benefit of providing high visibility in signs, some of which can be seen from up to 1.5 kilometers away, claims Wallstreet Pit. The New York Times states that a new LED sign in New York City will be bright enough to be readable even during high noon. Philips claims that their current state-of-the-art Luxeon K2 LEDs have outputs of at least 200 lumens at 12 volts DC with a current as little as 350 mA. Further, they dim far less than traditional lighting sources, with some experiencing only a 10% loss of light output after as many as 1,000 hours, and last for as long as 15 years under normal usage conditions. Several cities are considering switching from high pressure sodium lighting to LED lighting, including a pilot program of 34,000 street lamps slated for testing in Lansing, Michigan. 2.7 PIEZOBASED POWER GENERATION After doing several experiments regarding piezobased power generation Umedal sought after a device that would eliminate the need to charge up portables before taking them anywhere. The device would charge the mobile device enroute while traveling. To accomplish this, they constructed a piezo-generator that transforms mechanical impact energy to electrical energy by using a steel ball which impacts the generator. The steel ball is initially 5mm above a bronze disk . The ball falls and strikes the center of the disk producing a bending vibration. The ball continues to bounce on the disk till it stops. The piezo patch converts the vibrational energy of the bouncing ball to electrical energy and stores a voltage in a capacitor. They performed analyses on two things. The first case was on the first impact. The second case was on multiple impacts from the ball. For the first case, higher voltage and capacitance affects the generator. A higher voltage decreases the time during which the current flows. If the capacitance is small, the voltage will go up quickly, limiting the time current will flow. On the other hand, if the capacitance is large, it takes time for the voltage to build up and allows the current to flow 12
  13. 13. for more time. For the second case, the capacitance affects multiple impacts the same way it does for a single impact. 3 SYSTEM DEVELOPMENT 3.1 ENGINEERING DESIGN PROCESS Fig 3.1 3.2 PVDF SENSOR PRICES LIST 13
  14. 14. Table 3.1 3.3 TYPES OF BUZZERS 3.3.1 AC BUZZER 3.3.2 DC BUZZER 14
  15. 15. Fig 3.2 3.4 PIEZO BUZZER SPECIFICATIONS Table 3.2 1
  19. 19. Fig 4.1 4.2 WORKING 0 The piezoelectric transducers work on the principle of piezoelectric effect. 0 When mechanical stress or forces are applied to some materials along certain planes, they produce electric voltage. 0 This electric voltage can be measured easily by the voltage measuring instruments, which can be used to measure the stress or force. 0 By applying the mechanical load to piezoelectric path,the energy converts into electrical energy. 0 When a capacitor is connected to electric board,the energy get stored in the capacitor. 0 The electric board is connected to the LED module which emits light. 0 Finally the photo diode measures the intensity of light. 0 The voltage output obtained from these materials due to piezoelectric effect is proportional to the applied stress or force. 5
  20. 20. 0 The output voltage can be calibrated against the applied stress or the force so that the measured value of the output voltage directly gives the value of the applied stress or force. 0 The voltage output obtained from the materials due to piezoelectric effect is very small and it has high impedance. 0 To measure the output some amplifiers, auxiliary circuit and the connecting cables are required. 0 An Electric potential is developed across the face, and this electric potential is used to produce electric current which is used to glow the lights, LED,s, and further this we can charge the battery of our mobile or cellphones by connecting the device to the cellphone via. some USB device. 0 The diagram showing that as the pressure is applied to the faces there is a generation of electric current which is indicated by the Galvanometer. Fig 4.2 Pressure is applied to the Faces there is a Generation of Electric Current which is indicated by the Galvanometer. 4.3 PRECAUTIONS FOR USE • Do not apply DC bias to the piezoelectric buzzer; otherwise insulation resistance may become low and affect the performance. • Do not supply any voltage higher than applicable to the piezo- electric buzzer. 6
  21. 21. • Do not use the piezoelectric buzzer outdoors. It is designed for indoor use. If the piezoelectric buzzer has to be used outdoors, provide it with waterproofing measures; it will not operate normally if subjected to moisture. • Do not wash the piezoelectric buzzer with solvent or allow gas to enter it while washing; any solvent that enters it may stay inside a long time and damage it. • A piezoelectric ceramic material of approximately 100µm thick is used in the sound generator of the buzzer. Do not press the sound generator through the sound release hole otherwise the ceramic material may break. Do not stack the piezoelectric buzzers without packing. • Do not apply any mechanical force to the piezoelectric buzzer; otherwise the case may deform and result in improper operation. • Do not place any shielding material or the like just in front of the sound release hole of the buzzer; otherwise the sound pressure may vary and result in unstable buzzer operation. Make sure that the buzzer is not affected by a standing waves or the spikes. • Be sure to solder the buzzer terminal at 350°C max.(80W max.)(soldering iron trip) within 5 seconds using a solder containing silver. • Avoid using the piezoelectric buzzer for a long time where any corrosive gas (H2S, etc.) exists; otherwise the parts or sound generator may corroded and result in improper operation. • Be careful not to drop the piezoelectric buzzer. 4.4 ESTIMATION OF ELECTRIC CHARGE OUTPUT FOR PIEZOELECTRIC ENERGY HARVESTING One method of power harvesting is to use piezoelectric materials, which form transducers that are able to interchange electrical energy and mechanical strain or force. Therefore, these materials can be used as mechanisms to transfer ambient motion (usually vibration) into electrical energy that may be stored and used to power other devices. By implementing power harvesting devices, portable systems can be developed that do not depend on traditional methods for providing power, such as the battery, which has a 7
  22. 22. limited operating life. A significant amount of research has been devoted to developing and understanding power harvesting systems . The power harvesting system used the energy generated by the PVDF to charge a capacitor and power a transmitter that could send information regarding the strain of the beam a distance of 2m. Their model has been experimentally verified using a 1-d beam structure with peak power efficiencies of approximately 20%. Most of the previous studies all realized that the energy generated by the piezoelectric material must be accumulated before it can be used to power other electronic devices. 4.5 ADVANTAGES 0 High frequency response: They offer very high frequency response that means the parameter changing at very high speeds can be sensed easily. 0 High transient response: The piezoelectric transducers can detect the events of microseconds and also give the linear output. 0 The piezoelectric transducers are small in size and have rugged construction. 4.6 LIMITATIONS 0 Some of the limitations of piezoelectric transducers are: 0 1) Output is low: The output obtained from the piezoelectric transducers is low, so external electronic circuit has to be connected. 0 2) High impedance: The piezoelectric crystals have high impedance so they have to be connected to the amplifier and the auxiliary circuit, which have the potential to cause errors in measurement. To reduce these errors amplifiers high input impedance and long cables should be used. 0 3) Forming into shape: It is very difficult to give the desired shape to the crystals with sufficient strength. 8
  23. 23. 5 RESULTS & CONCLUSIONS 5.1 RESULTS S.No. Force Applied Intensity of light 1 2 3 4 5 Table 5.1 5.2 FUTURE SCOPE Series Piezoelectric materials embedded on road to glow the road lights as shown : Fig 5.1 In this figure we see the piezoelectric cells are embedded on the whole road and these embedded piezoelectric cells are connected with external charge storing device with the help of connectors, and the charge so developed are then supplied to all the street lights as shown in the figure. Economically competitive with the traditional carbon-based energy production.  The electrical storage system, which is integrated in the roads, rail roads, and runways, does not take up any new public space and functions in all weather conditions. 9
  24. 24. Once embedded into road ways or railways, generators require minimal maintenance.  These solutions can also serve as information gatherers in future ―smart roads‖ measuring a truck or rail car’s weight in real time, send data back through a self-powered’ wireless connection. These could be used in weighing stations. 5.3 APPLICATIONS 5.3.1 Cigarette Lighter Pressing the button causes a spring-loaded hammer to hit a piezoelectric crystal, producing a sufficiently high voltage electric current that flows across a small spark-gap, thus heating and igniting the gas. Fig 5.2 5.3.2 Armed Forces The armed forces toyed with the idea of putting piezoelectric materials in soldier’s boots to power radios and other portable electronic gear. 5.3.3 Night Clubs Several nightclubs, mostly in Europe have already begun to power their strobes and stereos using the force of hundreds of people pounding on piezoelectric lined dance floors. 10
  25. 25. Fig 5.3 5.3.4 Gyms Several gyms, notable in Portland and a few other places are powered by a combination of piezoelectric set ups and generators set up on stationary bikes. Piezoelectric Powered Music Instruments Fig 5.4 5.3.5 Harvesting From Human Body Capitalizing on the friction and heat created by walking, running and even just wearing jeans, engineers from Michigan Technological University, Arizona State University 11
  26. 26. devised a way to use this type of generated energy to charge portable electronic devices, like iPods and mobile phones. Fig 5.5 5.3.6 Piezoelectric road harvests traffic energy to generate electricity Fig 5.6 Isreali engineers are about to begin testing a 100 metre stretch of roadway embedded with a network of Piezo Electric Generators (IPEG™). The piezoelectric effect converts 12
  27. 27. mechanical strain into electrical current or voltage and the system is expected to scale up to 400 kilowatts from a 1-kilometre stretch of dual carriageway. The IPEG™ is a pioneering invention in the field of Parasitic Energy harvesting and generates energy from weight, motion, vibration and temperature changes and will certainly have other parasitic energy harvesting applications in many fields. Initially though, the system can be configured to generate and store energy from roads, airport runways and rail systems at the same time as delivering real-time data on the weight, frequency and spacing between passing vehicles. The harvested energy can be transferred back to the grid, or used for specific public infrastructure purposes such as lighting and widespread use of the system would enable far greater scrutiny and hence understanding of the behaviour of road vehicles. As such, the embedding of piezoelectric generators to create "smart roads" could eventually become an integral part of traffic management systems. The harvesting system of parasitic mechanical energy from roadways is based on the piezoelectric effect converts mechanical strain into electrical current or voltage. The harvested energy can be transferred back to the grid, or used for specific road infrastructure purposes. The infrastructure captures and stores energy for reuse. The generators are mounted with electronic cards supplying the storage system. The laying of the present system, (embedding the generators and electronic cards in to the roadway), can be done during paving of new roads or in the course of the maintenance work in existing roadways, so it’s entirely retrofittable to any road, and the heavier the vehicle, and the greater the number of vehicles, the greater the return, all the way to electricity production on an industrial scale. This means that parasitic energy of busy roads, railroads and runways near population centres can be converted into electrical energy that can run public lighting, or fed back into the grid. 5.3.7 Power Walking With Energy Floors Power walking isn’t just a health craze - it could produce electrifying results! 13
  28. 28. Fig 5.7 Energy Floors, a Netherlands-based company, wants to be a player in the sustainable energy market. They don’t just talk the talk, they walk the walk … literally. Their products, the Sustainable Energy Floor and Sustainable Dance Floor, convert footsteps into electricity. As a person steps on an Energy Floor tile, the tile flexes about 10 mm. That movement is converted into electricity - 15 Watts on average, and up to 25 Watts peak. The tiles are modular; connect 40 tiles together and the network can generate up to 1 kW. They wouldn’t give me details on the generator, except to say that it’s not piezoelectric. Based on the diagram below, it looks like a rack-and-pinion that drives a small permanent magnet generator. Fig 5.8 14
  29. 29. In addition to the tiles, the system includes a controller module that directs the flow of electricity. The 12V output can light LEDs (as in the Sustainable Dance Floor or a lighted walkway), power an external low-voltage device, or charge a battery. 5.3.8 Public Areas Blocks that light up when activated entice people to step on them. Put a few at each shopping mall and you have a playground that lets kids burn off their excess energy and turn it into electricity. Set them up in front of the stage at a Phish concert and you might generate enough electricity to power the amps during one of Trey Anastasio’s guitar solos. (Okay maybe that one is a little ambitious.) Fig 5.9 But it’s not just a high-tech toy. Energy Floors recently partnered with the Russian Railway Research Institute, which hopes to put Energy Floors on railroad platforms and high-traffic walkways. 15
  30. 30. Fig 5.10 They’ll also investigate the use of this technology to harvest energy from the movement of cars and trains. Frankly, I think piezoelectric transducers might be better for those applications. They’re less efficient than electromagnetic generators, but they might be more durable under heavy vehicular traffic. Fig 5.11 In keeping with the company’s sustainable focus, the floor tiles are made from recyclable materials. They have a 30 year expected lifetime. 16
  31. 31. 5.4 CONCLUSION When the pressure is applied on the face of the device, there is a deformation of charge carriers inside the crystals which will result in Electric field, and therefore an Electric potential is developed across the face, and this electric potential is used to produce electric current which is used to glow the lights, LED,s, and further this we can charge the battery of our mobile or cell phones by connecting the device to the cell phone via. some USB Device. The ability of piezoelectric equipment to convert motion from human body into electrical power is remarkable. It is a great hope that energy harvesting will rule the next decade in the technical field. We thereby conclude upon the project by generating light out of the stress applied on the piezoelectric material.This can solve many problems regarding the dependency on batteries, also to harvest energy , since the world is in need of energy. 17
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