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

The Application of a Triboelectric Energy Harvester in the Packaged Product Vibration Environment

Smart packaging technology is growing every year, complemented by the development of micro-electronic devices. These two trends in innovation create unique capabilities for monitoring and tracking packaged products in transit. Developing in tandem with this momentum of invention and micro-scaling of technology is the need for innovative ways to power these devices. This paper details a novel system that harvests energy from the vibration inherent in the transportation of packaged products, stores it, and uses it to power sensors that measure the very same environment from which the energy is harvested. Also accomplished in this research is the exploration of the physical and electrical durability of the energy harvester, as well as its sensitivity to environmental relative humidity. A triboelectric energy harvester converts mechanical energy to electrical energy, which is then collected and used to charge a rechargeable energy cell. This energy cell may then be used to power small electronic devices for a myriad of applications, such as temperature and humidity sensors, accelerometers, or GPS tracking devices. This energy harvester is constructed in the form of a tier sheet to be used within a unit load, replacing a corrugate sheet with a device that achieves the same purpose, while enabling power generation. This research details a unique use of the triboelectric energy harvesting method in its application in packaged product distribution, as well as conditions, such as physical durability of the harvester and humidity of its immediate environment. The triboelectric energy harvester developed is experimentally validated for use in generating power sufficient to charge a coin cell battery capable of powering various field data recorders, the requirements of which are detailed in this manuscript

Investigation of Nonlinear Piezoelectric Energy Harvester for Low-Frequency and Wideband Applications

This paper proposes a monostable nonlinear Piezoelectric Energy Harvester (PEH). The harvester is based on an unconventional exsect-tapered fixed-guided spring design, which introduces nonlinearity into the system due to the bending and stretching of the spring. The physical–mathematical model and finite element simulations were performed to analyze the effects of the stretching-induced nonlinearity on the performance of the energy harvester. The proposed exsect-tapered nonlinear PEH shows a bandwidth and power enhancement of 15.38 and 44.4%, respectively, compared to conventional rectangular nonlinear PEHs. It shows a bandwidth and power enhancement of 11.11 and 26.83%, respectively, compared to a simple, linearly tapered and nonlinear PEH. The exsect-tapered nonlinear PEH improves the power output and operational bandwidth for harvesting low-frequency ambient vibrations

Bioinspired Designs and Biomimetic Applications of Triboelectric Nanogenerators

The emerging novel power generation technology of triboelectric nanogenerators (TENGs) is attracting increasing attention due to its unlimited prospects in energy harvesting and self-powered sensing applications. The most important factors that determine TENGs’ electrical and mechanical performance include the device structure, surface morphology and the type of triboelectric material employed, all of which have been investigated in the past to optimize and enhance the performance of TENG devices. Amongst them, bioinspired designs, which mimic structures, surface morphologies, material properties and sensing/power generation mechanisms from nature, have largely benefited in terms of enhanced performance of TENGs. In addition, a variety of biomimetic applications based on TENGs have been explored due to the simple structure, self-powered property and tunable output of TENGs. In this review article, we present a comprehensive review of various researches within the specific focus of bioinspired TENGs and TENG enabled biomimetic applications. The review begins with a summary of the various bioinspired TENGs developed in the past with a comparative analysis of the various device structures, surface morphologies and materials inspired from nature and the resultant improvement in the TENG performance. Various ubiquitous sensing principles and power generation mechanisms in use in nature and their analogous artificial TENG designs are corroborated. TENG-enabled biomimetic applications in artificial electronic skins and neuromorphic devices are discussed. The paper concludes by providing a perspective towards promising directions for future research in this burgeoning field of study

Development of Triboelectric Devices for Self-powered Sensing And Energy Harvesting Applications

Due to the bulky size and limited lifespan of batteries, remote charging and energy har- vesting from the environment are becoming two trends to power miniaturized electronics. Tri- boelectric nanogenerator (TENG) is an emerging technology to convert mechanical energy to electricitical energy by the coupling of triboelectrification and electrostatic induction. It has been widely applied to self-powered sensing and energy generation by virtue of the simpler device configuration and broader material choices compared to conventional energy conversion technologies, such as electromagnetic and piezoelectric energy harvesters. In this thesis, it is the first time to presented a self-powered on-line ion concentration monitoring system based on the impedance matching effect of TENG. Other than handcrafted TENGs, the rotary disc-shaped TENG (RD-TENG) was fabricated by the industrial printed circuit board (PCB) technology, which could realize sophisticated design and low-cost fabrica- tion. Flowing water, as the energy source, in the pipeline was utilized to drive the RD-TENG and generate an open-circuit voltage (VOC) of ∼210 VP−P. The impedance matching effect of TENG as the sensing mechanism was studied thoroughly. Based on the impedance matching effect, an alarm circuit was designed for the demonstration and the alarm LED can be success- fully lit up by the change of NaCl concentration with only 1×10−5 mol/L, which showed a high sensitivity. Compared to environmental monitoring, healthcare monitoring requires further miniatur- ized size and better compatibility with electronics. To satisfy the demands, a novel micro tri- boelectric energy harvester (μTEH) was developed. Based on the μTEH, a propotyped acoustic energy transfer system was built via an ultrasound link. For the very first time, TENG was fab- ricated by Micro-electro-mechanical systems (MEMS) technologies in batch process, giving better integrated circuit (IC) integration. More importantly, it is also the first time that the size of TENG is brought into microscale. We demonstrated a prototyped acoustic energy transfer system for implanted devices that could generate 50 nW power on load resistor under 1 MHz, 132 mW/cm2 incident acoustic power. The μTEH also achieved a signal-to-ratio (SNR) of 20.54 dB and exhibited promising potential for wireless communication by modulating the in- cident ultrasound. Finally, detailed optimization methods were proposed to improve the output power of the μTEHs in the future

Review of Contemporary Energy Harvesting Techniques and Their Feasibility in Wireless Geophones

Energy harvesting converts ambient energy to electrical energy providing numerous opportunities to realize wireless sensors. Seismic exploration is a prime avenue to benefit from it as energy harvesting equipped geophones would relieve the burden of cables which account for the biggest chunk of exploration cost and equipment weight. Since numerous energies are abundantly available in seismic fields, these can be harvested to power up geophones. However, due to the random and intermittent nature of the harvested energy, it is important that geophones must be equipped to tap from several energy sources for a stable operation. It may involve some initial installation cost but in the long run, it is cost-effective and beneficial as the sources for energy harvesting are available naturally. Extensive research has been carried out in recent years to harvest energies from various sources. However, there has not been a thorough investigation of utilizing these developments in the seismic context. In this survey, a comprehensive literature review is provided on the research progress in energy harvesting methods suitable for direct adaptation in geophones. Specifically, the focus is on small form factor energy harvesting circuits and systems capable of harvesting energy from wind, sun, vibrations, temperature difference, and radio frequencies. Furthermore, case studies are presented to assess the suitability of the studied energy harvesting methods. Finally, a design of energy harvesting equipped geophone is also proposed

Energy Harvesters and Self-powered Sensors for Smart Electronics

This book is a printed edition of the Special Issue “Energy Harvesters and Self-Powered Sensors for Smart Electronics” that was published in Micromachines, which showcases the rapid development of various energy harvesting technologies and novel devices. In the current 5G and Internet of Things (IoT) era, energy demand for numerous and widely distributed IoT nodes has greatly driven the innovation of various energy harvesting technologies, providing key functionalities as energy harvesters (i.e., sustainable power supplies) and/or self-powered sensors for diverse IoT systems. Accordingly, this book includes one editorial and nine research articles to explore different aspects of energy harvesting technologies such as electromagnetic energy harvesters, piezoelectric energy harvesters, and hybrid energy harvesters. The mechanism design, structural optimization, performance improvement, and a wide range of energy harvesting and self-powered monitoring applications have been involved. This book can serve as a guidance for researchers and students who would like to know more about the device design, optimization, and applications of different energy harvesting technologies

Smart Materials and Devices for Energy Harvesting

This book is devoted to energy harvesting from smart materials and devices. It focusses on the latest available techniques recently published by researchers all over the world. Energy Harvesting allows otherwise wasted environmental energy to be converted into electric energy, such as vibrations, wind and solar energy. It is a common experience that the limiting factor for wearable electronics, such as smartphones or wearable bands, or for wireless sensors in harsh environments, is the finite energy stored in onboard batteries. Therefore, the answer to the battery “charge or change” issue is energy harvesting because it converts the energy in the precise location where it is needed. In order to achieve this, suitable smart materials are needed, such as piezoelectrics or magnetostrictives. Moreover, energy harvesting may also be exploited for other crucial applications, such as for the powering of implantable medical/sensing devices for humans and animals. Therefore, energy harvesting from smart materials will become increasingly important in the future. This book provides a broad perspective on this topic for researchers and readers with both physics and engineering backgrounds

Advanced Energy Harvesting Technologies

Energy harvesting is the conversion of unused or wasted energy in the ambient environment into useful electrical energy. It can be used to power small electronic systems such as wireless sensors and is beginning to enable the widespread and maintenance-free deployment of Internet of Things (IoT) technology. This Special Issue is a collection of the latest developments in both fundamental research and system-level integration. This Special Issue features two review papers, covering two of the hottest research topics in the area of energy harvesting: 3D-printed energy harvesting and triboelectric nanogenerators (TENGs). These papers provide a comprehensive survey of their respective research area, highlight the advantages of the technologies and point out challenges in future development. They are must-read papers for those who are active in these areas. This Special Issue also includes ten research papers covering a wide range of energy-harvesting techniques, including electromagnetic and piezoelectric wideband vibration, wind, current-carrying conductors, thermoelectric and solar energy harvesting, etc. Not only are the foundations of these novel energy-harvesting techniques investigated, but the numerical models, power-conditioning circuitry and real-world applications of these novel energy harvesting techniques are also presented