Development and efficiency optimizing of the human body energy converters

Nowadays it is known that the human body is continuous source of many types of energy and the devices used for collecting energy taken from the environment also have the required capabilities for the collection of the energy produced by the Human body (HB), but very limited and with very low efficiency. Low power and high yield converters are particularly needed in these cases of collecting energy from human activity and its movements due to the small amount of energy generated this way. But this situation can be improved. Enhancing or focusing the human movements by using mechanical amplifiers applied to the piezoelectric element. By doing so the input of energy in the element increases. As such increasing its output, therefore producing more energy

Nd Doped Zinc Oxide Based Flexible PVDF Polymer Composite for Energy Harvesting and Sensory Application

Flexible Piezoelectric devices have garnered a lot of attention for their potential as energy harvesters and transducers. Zinc Oxide particularly has been doped with different metals and has been incorporated in functional polymers in order to produce flexible piezoelectric devices. In this work, a Neodymium doped Zinc Oxide based flexible piezoelectric energy harvester and sensory device has been developed. For that, neodymium doped zinc oxide has been synthesized using wet chemical co-precipitation method and then has been incorporated in Polyvinylidene Difluoride (PVDF) polymer matrix along with Multiwalled Carbon Nanotubes (MWCNT) to produce flexible piezoelectric films. Silver paste was applied on both sides of the piezoelectric film to produce a compact and flexible piezoelectric energy harvesting device. The piezoelectric outputs of the device were tested at variable tapping frequency ranging from 60 BPM to 240 BPM and pressure (10 to 40 psi). The device was also tested with conventional electronics like bridge rectifiers, capacitors, resistors, LEDs to show its potential as an energy harvester. Compared to other modified ZnO-PVDF based unpoled piezoelectric energy harvesters, this device has shown the most open-circuit output voltage. The device produced the highest piezoelectric open-circuit voltage of 75.8 V. It has also shown an optimum power density of 12.55 μw/cm2 at 1MΩ load impedance. Energy harvesting capacity was further tested by placing the device between the shoe soles during running and jogging. The device also demonstrated uniform signals when it was attached to a part of the body and a specific motion was repeated. This study endorses the potential of Nd-ZnO/PVDF/MWCNT based piezoelectric energy harvester as the most efficient Piezoelectric Nanogenerator (PENG) which shows superior power generation along with self-powered sensory applications

Solid state generators and energy harvesters for waste heat recovery and thermal energy harvesting

This review covers solid state thermal to electrical energy converters capable of transforming low grade heat directly into electricity for waste heat recovery and thermal energy harvesting. Direct solid state heat engines, such as thermoelectric modules and thermionic converters for spatial temperature gradients, are compared with pyroelectric energy harvesters and thermomagnetic generators for transient changes in temperature. Temperature and size limitations along with the maturity of the technologies are discussed based on energy density and temperature range for the different generator technologies. Despite the low energy conversion efficiency with solid state generators, electric power density ranges from 4 nW/mm2 to 324 mW/mm2. The most promising sector to implement changes while reducing the primary energy consumption and saving resources, is the processing industry along with stationary and mobile electronics

Piezoelectric energy harvesting utilizing metallized poly-vinylidene fluoride (PVDF)

The primary objective of the enclosed thesis was to identify and develop a viable concept for an autonomous sensor system that could be implemented onto the surface of a road. This was achieved by an analysis of combinations of materials, sensing methods, power sources, microsystems, energy storage options, and wireless data transmission systems; the sub-systems required for an autonomous sensor. Comparison of sensing methods for the application of an on-road, autonomous sensor yielded a piezoelectric material as the ideal choice. A 52μm thin film of poly- vinylidene fluoride (PVDF) was chosen and coated with Ag electrodes on both sides.This was due to many constraints imposed by the intended environment including: physical, electrical, thermal, and manufacturing characteristics. One major hurdle in providing an autonomous sensor is the power source for the sensing, encoding, and transmission of data. Research involved determining the option best suited for providing a power source for the combination of sensors and wireless telemetry components. An energy budget of 105μJ was established to determine an estimate of energy needed to wirelessly transmit data with the selected RF transmitter. Based on these results, several candidates for power sources were investigated, and a piezoelectric energy harvesting system was identified to be the most suitable. This is an ideal case as the sensor system was already based on a piezoelectric material as the sensing component. Thus, a harvesting circuit and the sensor can be combined into one unit, using the same material. By combining the two functions into a single component, the complexity, cost and size of the unit are effectively minimized. In order to validate the conclusions drawn during this sensor system analysis and conceptual research, actual miniaturized systems were designed to demonstrate the ability to sense and harvest energy for the applications in mind. This secondary aspect of the research was a proof-of-concept, developing two prototype energy harvesting/sensing systems. The system designed consisted of a PVDF thin film with a footprint of 0.2032 m x 0.1397m x 52μm. This film was connected to an energy-harvesting prototype circuit consisting of a full-wave diode bridge and a storage capacitor. Two prototypes were built and tested, one with a 2.2μF capacitor, the other with a 0.1mF capacitor. The film was first connected to an oscilloscope and impulsed in an open circuit condition to determine the sensor response to a given signal. Secondly, the energy harvesting circuits were tested in conjunction with the film to test the energy supply component of the system. Lastly, the film and both energy-harvesting systems underwent full scale testing on a road using a vehicle as the stimulus. Both systems showed excellent rectification of the double polarity input with an evident rise in voltage across the capacitor, meaning energy was harvested. Typical results from the tests yielded 600-800mV across the 2.2μF capacitor, harvesting only a few μJ of energy. The 0.1mF capacitor system yielded approximately 4V per vehicle axle across the capacitor, harvesting 400-800μJ of energy. This equates to 4-8 times the required energy for wireless data transmission of the measurement data, which was estimated by other research groups to be on the order of 105μJ for the given system, and therefore proves the concept both, for bench-top and full-scale on-road experiments under controlled laboratory conditions

Electrostatic Conversion for Vibration Energy Harvesting

This chapter focuses on vibration energy harvesting using electrostatic converters. It synthesizes the various works carried out on electrostatic devices, from concepts, models and up to prototypes, and covers both standard (electret-free) and electret-based electrostatic vibration energy harvesters (VEH).Comment: This is an author-created, un-copyedited version of a chapter accepted for publication in Small-Scale Energy Harvesting, Intech. The definitive version is available online at: http://dx.doi.org/10.5772/51360 Please cite as: S. Boisseau, G. Despesse and B. Ahmed Seddik, Electrostatic Conversion for Vibration Energy Harvesting, Small-Scale Energy Harvesting, Intech, 201

System-level simulation of a self-powered sensor with piezoelectric energy harvesting

This paper presents a complete system simulation of a self-powered communication module. The components are described with the Verilog-A language, that allows to merge the electrical and mechanical models of the system. The self-powered sensor system is composed by an energy harvesting piezoelectric generator that powers a RF transmitter. The simulations here presented compare between the case of a battery-less and battery-powered system. The results obtained with the simulation model implemented allow to show how design choices of the system change the periodicity of the transmission and the ability to recharge the battery.Peer Reviewe

Doctor of Philosophy

dissertationMicroelectromechanical systems (MEMS) resonators on Si have the potential to replace the discrete passive components in a power converter. The main intention of this dissertation is to present a ring-shaped aluminum nitride (AlN) piezoelectric microreson

Thermal and Mechanical Energy Harvesting Using Lead Sulfide Colloidal Quantum Dots

The human body is an abundant source of energy in the form of heat and mechanical movement. The ability to harvest this energy can be useful for supplying low-consumption wearable and implantable devices. Thermoelectric materials are usually used to harvest human body heat for wearable devices; however, thermoelectric generators require temperature gradient across the device to perform appropriately. Since they need to attach to the heat source to absorb the heat, temperature equalization decreases their efficiencies. Moreover, the electrostatic energy harvester, working based on the variable capacitor structure, is the most compatible candidate for harvesting low-frequency-movement of the human body. Although it can provide a high output voltage and high-power density at a small scale, they require an initial start-up voltage source to charge the capacitor for initiating the conversion process. The current methods for initially charging the variable capacitor suffer from the complexity of the design and fabrication process. In this research, a solution-processed photovoltaic structure was proposed to address the temperature equalization problem of the thermoelectric generators by harvesting infrared radiations emitted from the human body. However, normal photovoltaic devices have the bandgap limitation to absorb low energy photons radiated from the human body. In this structure, mid-gap states were intentionally introduced to the absorbing layer to activate the multi-step photon absorption process enabling electron promotion from the valence band to the conduction band. The fabricated device showed promising performance in harvesting low energy thermal radiations emitted from the human body. Finally, in order to increase the generated power, a hybrid structure was proposed to harvest both mechanical and heat energy sources available in the human body. The device is designed to harvest both the thermal radiation of the human body based on the proposed solution-processed photovoltaic structure and the mechanical movement of the human body based on an electrostatic generator. The photovoltaic structure was used to charge the capacitor at the initial step of each conversion cycle. The simple fabrication process of the photovoltaic device can potentially address the problem associated with the charging method of the electrostatic generators. The simulation results showed that the combination of two methods can significantly increase the harvested energy