ABSTRACTEnergy harvesting from ankle boot using polymer by piezoelectric mechanism. Day to day mankind is utilizing some kind of energy from the available environment like sun rays, wind, water, etc. likewise even from the actions of shoes itself we can harvest energy and make it useful for some applications.Day to day inventions teach us that even that small amount of energy can be utilized for the existing actions. This project describes about the energy harvesting. Harvest maximum energy from the shoes and at the same time without affecting the green environment. I am developing the boot which could enable us to harvest the energy by mechanical actions like running, bending, walking. This energy can be stored in a battery and used for some us applications like charging smartphones, also for activating GPS systems.Key words: shell patterns, stuck on construction, polymer based sensors, abaqus finite element analysis.

CHAPTER 1INTRODUCTIONENERGY HARVESTINGEnergy harvesting also known as power harvesting is the process by which energy is derived from external sources (e.g. solar power, thermal energy, wind energy, salinity gradients, and kinetic energy), captured, and stored for small, wireless autonomous devices, like those used in wearable electronics and wireless sensor networks.Energy harvesters provide a very small amount of power for low-energy electronics. Energy harvesting devices converting ambient energy into electrical energy have attracted much interest in both the military and commercial sectors. Energy can also be harvested to power small autonomous sensors such as those developed using MEMS technology. These systems are often very small and require little power, but their applications are limited by the reliance on battery power.There are many small-scale energy sourcesPhotovoltaics is a method of generating electrical power by converting solar radiation into direct current electricity using semiconductors that exhibit the photovoltaic effect. Photovoltaic power generation employs solar panels composed of a number of cells containing a photovoltaic material.Micro wind turbine are used to harvest wind energy readily available in the environment in the form of kinetic energy to power the low power electronic devices such as wireless sensor nodes.Piezoelectric crystals or fibers generate a small voltage whenever they are mechanically deformed. Vibration from engines can stimulate piezoelectric materials, as can the heel of a shoe, or the pushing of a button.Electroactive polymers (EAPs) have been proposed for harvesting energy. These polymers have a large strain, elastic energy density, and high energy conversion efficiency. The total weight of systems based on EAPs is proposed to be significantly lower than those based on piezoelectric materials.PIEZOELECTRIC CONCEPTDEFINITION: piezoelectricity, also called the piezoelectric effect, is the ability of certain materials to generate an AC (alternating current) voltage when subjected to mechanical stress or vibration, or to vibrate when subjected to an AC voltage, or both. The most common piezoelectric material is quartz. Certain ceramics, Rochelle salts, and some conductive polymers also exhibit this effect.Piezo buzzer exploits the piezoelectric property of the piezo electric crystals. The piezoelectric effect may be direct piezoelectric effect in which the electric charge develops as a result of the mechanical stressor reverse or indirect piezoelectric effect (Converse piezoelectric effect) in which a mechanical force such as vibration develops due to the application of an electric field.Piezoelectric materials have the ability to transform mechanical strain energy into electrical charge. Piezo elements are being embedded in walkways to recover the people energy of footsteps.Example for piezoelectric

EXISTING PIEZOELETRIC MATERIALS

PIEZOELECTRIC POLYMERSA piezoelectric polymer is a material having piezoelectricity. It is the ability of materials, which is the property that the polarization of a material change by applying stress and/or strain generated by changing polarization.POLYMERS THAT EXIHIBIT THE PIEZOELECTRIC PROPERTY

CHAPTER 2LITRETURE STUDYPawel Zylka-Current progress in ambient energy harvesting using piezoelectric materials and electro active polymers. This paper describes about the properties of the piezoelectric material and its working process while in swing and stance phase and also the values of the voltage impulse developed during the process. Jacob Munk-Stander(2006) Evaluation of Piezoelectric Film Sensors for In-Shoe Pressure Measurement. His paper describes about the shape, design and size of the piezoelectric material which is used in the project and also shows the sensor position in the bottom soles.Jin-rae cho (2009)Landing impact analysis of sports shoes using 3-D coupled foot-shoe finite element model. Implantation of the analytical approach gives the better results when compare to the trial and error method . so by using the finite element analysis software like ANSYS and ABAQUS gives the precise value when compared to the trial and error method.

CHAPTER 3SELECTION OF RAW MATERIALSThere are several types of raw materials available for the different parts of the shoes.They areOutsolePolyurethane(pu)Polyviniylchoride(pvc)Thermoplastic rubber(tpr)Ethyl vinyl acetate(eva)Micro cellular rubber(mcr)InsolePolyurethane(pu) foamPolyviniylchoride(pvc)Ethyl vinyl acetate(eva)UpperLeather materialSynthetic fibreMICRO CELLULAR RUBBER(MCR) OUTSOLE

Cellular rubbers are porous rubber qualities with all-round closed cells. They are manufactured in accordance with the expansion process using gas-developing agents. The cellular structure distinguishes cellular rubber (left picture) from sponge rubber skin/skin (right picture), which contains partly opened cells, and sponge rubber, consisting of completely opened cells. Thus cellular rubber in contrast to sponge rubber skin/skin does not require an outer skin in order to use it as a gasket or lining. POLYURETHANE INSOLEPolyurethane (PUR and PU) is a polymer composed of a chain of organic units joined by carbamate (urethane) links.Chemical structure of PU

Polyurethane polymers are traditionally and most commonly formed by reacting a di- or polyisocyanate with a polyol. Both the isocyanates and polyols used to make polyurethanes contain on average two or more functional groups per molecule.

POLYURETHANE FOAMS

LIST OF PU FOAM APPLICATIONLow-density flexible foam used in upholstery, bedding, and automotive and truck seatingLow-density rigid foam used for thermal insulation and RTM coresSoft solid elastomers used for gel pads and print rollersLow density elastomers used in footwearHard solid plastics used as electronic instrument bezels and structural partsFlexible plastics used as straps and bandsETHYLVINYL ACETATE INSOLEEthylene-vinyl acetate (EVA), also known as poly(ethylene-vinyl acetate) (PEVA), is the copolymer of ethylene and vinyl acetate. The weight percent vinyl acetate usually varies from 10 to 40%, with the remainder being ethylene.

Chemical structure of EVA

It is a polymer that approaches elastomeric materials in softness and flexibility, yet can be processed like other thermoplastics. The material has good clarity and gloss, low-temperature toughness, stress-crack resistance, hot-melt adhesive waterproof properties, and resistance to UV radiation. EVA has a distinctive vinegar odor and is competitive with rubber and vinyl products in many electrical applications.EVA INSOLE

PRESSURE SENSORS AND FLEX FORCE SENSORSPIEZOELECTRIC PRESSURE SENSORPiezoelectric Pressure Sensors measure dynamic pressures. They are generally not suited for static pressure measurements. Dynamic pressure measurements including turbulence, blast, ballistics and engine combustion under varying conditions may require sensors with special capabilities. Fast response, ruggedness, high stiffness, extended ranges, and the ability to also measure quasi-static pressures are standard features associated with PCB quartz pressure sensors.

FLEX FORCE PIEZOELETRIC SENSORPVDF FILMSThe piezo film sensors elements are rectangular elements of piezo film with pvdf screen printed electrodes. They are available in a variety of different sizes and thicknesses. The film element produces more than 10 millivolts per microstrain, about 60 dB higher than the voltage output of a foil strain gage. The capacitance is proportional to the area and inversely proportional to the thickness of the element. The series sensors are the simplest form of piezo film sensors, used primarily as dynamic strain gages and contact microphones for vibration or impact detection. They can be readily adhered to a surface with double-sided tape or epoxy. Lead attachment can be achieved by compressive clamping, crimps, eyelets, conductive epoxy or low temperature solders. These elements are supplied with a thin urethane coating over the active sensor area; the lead attachment legs are free of the insulating urethane coating.Pvdf coated flex sensors Polyvinylidene fluoride (PVDF) exhibits piezoelectricity several times greater than quartz. Unlike ceramics, where the crystal structure of the material creates the piezoelectric effect, in polymers the intertwined long-chain molecules attract and repel each other when an electric field is applied.PVDF is a specialty plastic material in the fluoropolymer family

Chemical formula for pvdf

Some properties about pvdfIt is used generally in applications requiring the highest purity, strength.Resistance to solvents, acids, bases and heat and low smoke generation during a fire event.It has low density (1.78 g/cm3)It has relatively low melting point around 177 C.Flexing angle of the sensor

CHAPTER 4BOOT DEVELOPMENTTwo major portions of the boot development are upper construction and customized outsole.

OUTSOLE DESIGN

SHELL PATTERNS AND UPPER

ENERGY GENERATING INSERTS These insert consist of series of layers combined with piezoelectric sensors to form insole like material. The maximum thickness of the insert is upto 5mm.

Materials used in inserts are Pu foam in different densities MCR rubber EVA INSOLES Pvdf polymer films pressure sensors Cellulose board Some wires Tapes

Construction of energy generating inserts

Final view of the energy generating inserts

CHAPTER 5Methodology Gait analysis To mark the position to place the sensor is important factor among these things. To determine that position gait analysis is needed.Gait analysis for walking

From the analysis, it is clearly seen that pressure distribution are mostly peak at heel and metatarsal region for the normal walking person. Even though precise position gives better output from sensors. Therefore the major position to place sensor are Heel region sudden impact regionMetatarsal region gradual flexing region

Heel region heel portion of the shoe receives the major heel strike or sudden impact for samml amount of time. Piezoelectric pressure sensor is effective for this regionMetatarsal region in this region flexing will occur which is gradual in nature when compared to the heel strike. Duration of pressure distribution is lightly more comparing to the heel region. Flex force sensor can be used. Normal walking with foam materialsTo ensure the protection of sensor, there certain things are followed Considering the weight subjects and impact strength of sensors. Pu based foams are used above the energy inserts in order to protect the sensor from physical damage and also to distribute the pressure uniformly all over the area.Trial and error methodWhole shoe flexing machineOnce the energy inserts are made and inserted in to the boot which can be tested using the whole shoe flexing machine.Whole shoe flexing machine

Footwear is clamped to the machine at the toe end using the appropriate toe clamp from one of five pairs supplied. The heel end is secured to the flexing bar. A predetermining counter is fitted and once the appropriate number of flexes has been registered, it will stop the machine so that the shoe can be inspected.The moving parts of the machine are covered by a hinged guard which is fitted with the latest safety device to prevent access while the machine is still in use. The machine is robust and non-corrosive materials are used where applicable in its construction.From this machine it can be tested how the sensor behaving as per the cyclic flexing of the shoe and small battery or capacitor is fixed to store the electrical impulse for the future charging.Real time methodWalking with respective weight subjectOnce trial and error method completed. Then the weight subject is chosen for the real time experiment.In which the subject is wear the boot with the energy generating inserts for the particular period of time like upto 6 hoursDuring the 6 hours the boot is under constant impact loading, bending, flexing.

CHAPTER 6TABULATON AND GRAPHICAL REPRESENTAIONMeasured values from the normal walkingWeight/thickness(MCR)Minimum voltage (V)Maximum voltage (V)

~60/without insert1.95.2

~60/5mm insert1.13.4

~60/10mm insert0.451.6

Graphical representation of measured voltage

Measured values from trial and error methodwhole shoe flexing machineshoe with energy harvesting inserts placed for flexing for the time period of 5 hours.voltage measured before flexing - 3.2vvoltage measured after flexing - 3.9vrechargeable (li-ion battery) was used as the storage device for the further application. measured values from real time methodwalking with respective weight subjectTo perform real time experiment, the energy insert is implemented into security boots.subject weight - ~70kgshoe size - 7EPaction performed - walking, standing, bendingtime taken - 5hours approx.current generation - discharging 2000mAHanalysis Voltage required for charging phones-3.7vWhile manual loadingVoltage detected in pvdf film -13v and above Voltage detected in solid sensor -9v and aboveWhile walkingVoltage detected in pvdf film -7vVoltage detected in solid sensor -4.5v

CHAPTER 7Conclusion It is clearly shows that the combined output of the pressure and flex sensors gives enormous amount of output which can be used of various purpose.But still this flex sensor is at high cost and low durability makes some barricade to this project.So using the pressure sensor on both heel and metatarsal region gives the better life and also equivalent output comparing to the previous one.From the generation of energy this can charge mobile phones, series of led light and also 60 watts bulb.Future scopeThere are many number of modification can be proposed in future like.Conducting polymers or electro active polymers which can be used as a outsole material for larger requirement of power.Increasing the area of the pvdf film can totally change the output.It is also proposed that this exiting technology can be converted into wireless charging concept.

CHAPTER 8REFERENCESubramania. A., (2006) Structural and electrochemical properties of micro-porous polymer blend electrolytes based on PVdF-co-HFP-PAN for Li-ion battery applications,Journal of power sources vol.153 PP 177-182Jason Tak-Man Cheung., (2006) Finite Element Modeling of the Human Foot and Footwear, Abaqus users conferenceJin-Rae Cho,. (2009) Landing impact analysis of sports shoes using 3-D coupled foot-shoe finite element model ,Journal of mechanical and technology vol.53 PP 2583- 2591Weihua Pu, Xiangming He., Preparation of PVDFHFP microporous membrane for Li-ion batteries by phase inversion, ,Journal of power sources vol.272 PP 11-14