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

Tunable, multi-modal, and multi-directional vibration energy harvester based on three-dimensional architected metastructures

Conventional vibration energy harvesters based on two-dimensional planar layouts have limited harvesting capacities due to narrow frequency bandwidth and because their vibratory motion is mainly restricted to one plane. Three-dimensional architected structures and advanced materials with multifunctional properties are being developed in a broad range of technological fields. Structural topologies exploiting compressive buckling deformation mechanisms however provide a versatile route to transform planar structures into sophisticated three-dimensional architectures and functional devices. Designed geometries and Kirigami cut patterns defined on planar precursors contribute to the controlled formation of diverse three-dimensional forms. In this work, we propose an energy harvesting system with tunable dynamic properties, where piezoelectric materials are integrated and strategically designed into three-dimensional compliant architected metastructures. This concept enables energy scavenging from vibrations not only in multiple directions but also across a broad frequency bandwidth, thus increasing the energy harvesting efficiency. The proposed system comprises a buckled ribbon with optional Kirigami cuts. This platform enables the induction of vibration modes across a wide range of resonance frequencies and in arbitrary directions, mechanically coupling with four cantilever piezoelectric beams to capture vibrations. The multi-modal and multi-directional harvesting performance of the proposed configurations has been demonstrated in comparison with planar systems. The results suggest this is a facile strategy for the realization of compliant and high-performance energy harvesting and advanced electronics systems based on mechanically assembled platforms

Design of high-performance Triboelectric Nanogenerators (TENGs) for energy harvesting applications

The growing concerns around the long-term viability of the fossil fuel-based energy and its associated environmental cost are necessitating new research paradigms for energy generation and harvesting. An attractive and effective way to respond to the current energy crisis is through the harvesting of ambient mechanical energy from our environment. The conventional mechanical energy harvesting technologies are highly dependent on either the use of rare earth magnetic materials, high precision microfabrication techniques or composed of brittle materials, which are required to be driven at very high resonant frequencies, not frequently encountered beyond an industrial setting. Recently, triboelectric nanogenerators (TENG), based on the triboelectrification and electrostatic induction effects, have been demonstrated as a novel harvesting technique to collect and transform ambient mechanical energy into electric power. Unlike the other mechanical energy harvesters, the low-cost TENGs fabricated using commodity polymers and facile fabrication techniques, operate at low frequencies (1-10 Hz) with a high energy conversion efficiency. One of the key areas in TENG research is the enhancement of their electrical output to make them suitable for either making a self-powered system viable or powering small portable electronics directly. Except for the judicious use of tribo-materials or the tribo-layer architecture optimisation, the rest of the methods for enhancing the TENG output are reliant on expensive equipment and complicated processing, that undermine the advantages of TENGs and may not provide the required stability and reliability. This PhD study aims to establish novel strategies to enhance output performance of TENG by developing new tribo-materials and phenomena such as coupling of tribo-piezoelectric effects to showcase potential applications of the TENG devices. The research work conducted and the achievements are summarized as follows. Firstly, a novel output performance improvement strategy of utilising stress-induced polarization effect of the piezoelectric materials was proposed. An interfacial layer of piezoelectric zinc oxide (ZnO) nanosheets was deposited to generate additional piezoelectric charge induced by the vertical contact-separate generation cycle. This extra piezoelectric charge is injected into the upper polydimethylsiloxane (PDMS) tribo-negative layer for the enhancement of the surface charge density from ~110 μC.m-2 to ~225.7 μC.m-2. The introduction of the ZnO and Zn-Al:Layered Double Hydroxides (LDH), as charge injection layer and anionic clay, enhanced the instantaneous power output from ~11 W.m-2 to 47 W.m-2. Subsequently, based on a similar principle, a novel composite of lead-free perovskite, zinc stannate (ZnSnO3), and a fluoropolymer, poly(vinylidene fluoride), PVDF, was proposed for the stress-polarisation tribo-negative behaviour with a simplified structure. The PVDF-ZnSnO3 composite membranes were realised through a facile phase-inversion technique leading to higher piezoelectric constant (76.3 pm.V-1) and β-phase (72%) for the composites. When applied to the TENG devices, the PVDF-ZnSnO3 membranes allowed spontaneous polarisation effects which led to significant enhancement of the electrical outputs, with maximum peak-to-peak voltage and effective transferred current density of ~600 V and ~206 µC.m-2, respectively. The surface charge enhancement and distribution of the composite membrane were also probed and demonstrated through the electrostatic force (EFM) and piezoelectric force microscopy (PFM). To overcome the difficulty in processing of the currently known most tribo-negative material, polytetrafluoroethylene (PTFE), an emulsion electrospinning technique incorporating polyethene oxide (PEO) was introduced. It was observed that the subsequent thermal removal of PEO led to a significant degradation in the surface charge density of the obtained PTFE nanofibrous membranes, which was overcome using a facile negative ion-injection process. The measured electrical outputs, with a maximum peak-to-peak voltage output of ~900 V and charge density of ∼149 μC.m−2, demonstrated the excellent effect of the enhanced contact area to the improvement of the outputs. The work eliminates the demonstrated need for surface micro structuring using reactive ion etching of PTFE surfaces by introducing a relatively simple, costeffective, and environmentally friendly technique for fabricating fibrous fluoropolymers tribonegative layer for the energy harvesting applications. Finally, a unique mouldable material, aniline formaldehyde resin (AFR) was synthesised and characterised. The synthesised AFR, as a resinous polymer with significant amine (-NH2) groups acquires the most surface positive charge, is applied as a tribo-positive material. The heatpressed AFR thin-film based TENG was subsequently tested to demonstrate its outstanding performance serving as a tribo-positive layer compared to the Polyamide 6 (PA6) and polyethene oxide (PEO), as one of the most common used tribo-positive materials. In addition, a Kelvin Probe Force Microscopy (KPFM) was subsequently employed to study the surface potential of the produced AFR layer and the surface potential change of the contact layers during the energy generation cycles. All of the produced high-performance TENGs (power output ranging from 9 - 47 W.m-2) have the potential to be utilised further in enabling self-powered systems and can serve as a new alternative energy harvesting source of great significance

Advance in Energy Harvesters/Nanogenerators and Self-Powered Sensors

This reprint is a collection of the Special Issue "Advance in Energy Harvesters/Nanogenerators and Self-Powered Sensors" published in Nanomaterials, which includes one editorial, six novel research articles and four review articles, showcasing the very recent advances in energy-harvesting and self-powered sensing technologies. With its broad coverage of innovations in transducing/sensing mechanisms, material and structural designs, system integration and applications, as well as the timely reviews of the progress in energy harvesting and self-powered sensing technologies, this reprint could give readers an excellent overview of the challenges, opportunities, advancements and development trends of this rapidly evolving field

Development of Acoustic Metamaterial Noise Barriers and Simultaneously Harvesting Energy Using Smart Materials

In our surroundings abundant energy, we either feel through component vibration or hear noises from acoustic sources. Harvesting these unused and untapped green energy in the form of ambient vibration, and acoustic sounds is an emerging field of research in recent years. Utilization of the energy within a wide band of the frequency spectrum originated from the vibrational sources alone stands as one of the most promising ways to power small electronic devices, smartphones, local structural health monitoring sensors, home, and workshop appliances. These abundant sources of green energy are available in almost all the engineering industries, workshops, manufacturing facilities, construction zones, and in our daily operations. Particularly aerospace, mechanical, and civil sectors have plenty of such scenarios where the energy used is lost through vibration and acoustic noises. Continuously running machinery in a workshop, ambient vibration in a manufacturing facility, vibrating wings of an aircraft, high dB aircraft noise near airports, noise in metallurgical plants, power plants, vehicle noise near a roadside facility, etc. are few examples of the ambient source of energy that can be harvested which are otherwise wasted. If a suitable mechanism is devised, the vibration and acoustic noise sources can be equipped to trap and reclaim the energy to create local power sources. Researchers proposed many such methods in the past two decades. However, only recently researchers including us proposed that carefully engineered metamaterials can also be used for energy harvesting. Metamaterials are man-made materials that behave uniquely and possess exclusively desired properties that are not found in natural materials. Usually, it is the combination of two or more materials and can be engineered to perform specific tasks that are not possible with traditional materials. These were initially discovered in photonics while working with electromagnetic radiation. An electromagnetic counterpart of wave propagation in mechanics, i.e. phononics with acoustic waves were found to be affected by the metamaterials. These acoustic metamaterials when carefully designed are also capable of affecting the wave propagation characteristics through fluids such as air. Many acoustic metamaterials have gone beyond its definition but still, characterize the waveguiding properties. They are classified under the passive modalities of acoustics to affect the sound and vibration mitigation. Incorporation of smart materials while constructing acoustic metamaterial, can enhance the multifunctionality of these materials in both passive and active ways. A prospective application field for such acoustic metamaterials is energy harvesting from low-frequency vibrations. Conventionally, passive acoustic metamaterials are visualized as noise barrier materials to filter roadside and industrial noises. This application can get extended to the aerospace application where mitigation of engine noise inside the cabin is challenging. Irrespective of their target applications, acoustic metamaterials integrated with smart materials can scavenge the very green energy that they are designed to absorb and mitigate. First, in this research work, a recently proposed method of creating Acoustoelastic Metamaterial (AEMM) is used to investigate further if that can be used to harvest energy from the industrial noise barriers. It is known that noise barriers are designed to minimize noise outside the boundary like the noise barriers seen beside the highways. Construction materials like concrete, steel, vinyl, wood, or earth mounds are used in the industrial sound barriers that can reduce the sound pressure level (dB) on the other side of the barriers. In this work, a novel metamaterial wall (MetaWall) is proposed to redefine the industrial sound isolation wall using the integrated AEMM units. In this part, wave isolation and energy harvesting capabilities of the acoustic metamaterial is fused to propose MetaWall unit bricks, which are made of rubber-metal-concrete composite, as an industrial building material. Secondly, it is proposed that such acousto-elastic metamaterial (AEMM) models can also be used in the aerospace industry to power the online NDE/SHM sensors, e.g. piezoelectric wafer active sensors which are widely used. Hence, further in this part, a rigorous study is made to find the actual power required by the online NDE / SHM sensors such that a similar amount of power can be harvested by the AEMM model and stored in a battery for scheduled scans. The ultimate goal of this second study is to minimize the size of the proposed AEMM model to make it suitable for aerospace applications on-board. With changes in the materials of the cell constituents, it is shown that the power outputs from a similar model can be significantly altered and further optimized. A parametric study is also performed to show the variation of the output power. Finally, based on the learning a plate-type metamaterial is proposed to harvest a required optimum amount of energy from the ambient vibration with dominant frequency as low as 100Hz. In the third section, a spiral-shaped acoustic metamaterial is proposed which has dual functionality of noise filtering and energy harvesting over a wider range of frequencies. A work in progress presented with a proposed timeline to complete the dissertation. This acoustic metamaterial has a comparatively high reflection coefficient closer to the anti-resonance frequencies, resulting in high sound transmission loss. The filtered noise is trapped inside the cell in the form of strain energy. The spiral design is also sensitive to the vibration due to trampoline shaped in highly flexible polymeric piezoelectric material attachments inside the cell. This also makes it capable of harvesting energy using vibration. This is a promising acoustoelastic metamaterial with multifunctionality properties for future applications. Hence, it is claimed that if metamaterials are employed to reduce or suppress the noise and make use of the trapped energy which is any way wasted could be harvested to power the local electronic devices. The new solution could make a transformative impact on the 21st century’s green energy solutions. Calculated placement of smart materials in the cell-matrix can help to extract the strain energy in the form of power. The acoustic metamaterial cell designs presented in this research have the capability of isolating noise and reducing diffraction by trapping sound in a wide range of frequencies and at the same time recover the trapped abundant energy in the form of electrical potential using piezoelectric materials

A Novel Design Development for Piezoelectric Energy Harvesting Device

As more and more small electronic equipment enters people's lives, the power supply demand for these small electronic devices is also increasing. For small electronic devices, batteries are usually used for power supply, but for remote areas, frequently changing batteries is a complex job. Energy harvesting is a good way to solve this problem, such as photovoltaic batteries. Piezoelectric energy harvesting, as a method of energy harvesting, can generate unconventional clean energy through mechanical vibrations present in the environment. Due to the advantages of simplicity in structure, and low manufacturing and maintenance costs, piezoelectric energy harvesting holds great potential, especially for developing countries. Firstly, the thesis summarizes and analyses various types of existing piezoelectric energy harvester designs, identifying their shortcomings and potential areas for development. This provides a theoretical foundation for future research. Secondly, a novel galloping piezoelectric energy harvesting design, "a reverse C shape with a tail design," is proposed. Experimental and simulation analysis in a wind tunnel demonstrates that this design achieves a 25-fold increase in power output compared to existing designs at a wind speed of 5m/s. Furthermore, at a wind speed of 7m/s, the power output reaches 2.15mW, which can effectively meet the daily power requirements of specific electronic devices, such as hearing aids. In addition, this thesis also studied each parameter of the design, such as the length of the tail, the thickness of the "C shape", the selection of the cantilever beam, etc., which determine the impact of each parameter on the power output. The end of this thesis provides theoretical support through simulation studies, and suggestions for future research are provided. Overall, this thesis provides a new design for piezoelectric energy harvesters and also provides a broader perspective and theoretical support for the future development of this type of energy harvester

Organic-Inorganic Nanomaterial Based Highly Efficient Flexible Nanogenerator for Self-Powered Wireless Electronics

As the world progresses towards artificial intelligence and the Internet of Things (IoT), self‐powered sensor systems are increasingly vital for sensing and detection. Nanogenerators, a new technology in energy research, enable the harvesting of normally wasted energy from the environment. This technology scavenges a wide range of ambient energies, meeting the ever-expanding energy demands as conventional fossil fuel sources are depleted. This research involves designing and fabricating high-performance flexible piezoelectric nanogenerators (PENGs) and triboelectric nanogenerators (TENGs), using novel organic-inorganic hybrid nanomaterials for wireless electronics. Structural health monitoring (SHM) is crucial in the aerospace industry to enhance aircraft safety and consistency through reliable sensor networks. PENGs are promising for powering wireless sensor networks in aerospace SHM applications due to their sustainability, durability, flexibility, high performance, and superior reliability. This research demonstrated a self-powered wireless sensing system based on a porous PVDF (polyvinylidene fluoride)-based PENG, which is ideal for developing auto-operated sensor networks. The porous PVDF film-based PENG, enhanced output current by ~ 11 times and output voltage by ~ 8 times, respectively, compared to a pure PVDF-based PENG. The PENG device generated sufficient electrical energy to power a customized wireless sensing and communication unit and transfer sensor data every ~ 4 minutes. This PENG could harness energy from automobile vibration, reflecting the potential for real-life SHM systems. Subsequently, a novel, self-assembled, highly porous perovskite (FAPbBr2I)/polymer (PVDF) composite film was designed and developed to fabricate high-performance piezoelectric nanogenerators (PENGs). The porous structure enlarged the bulk strain of the piezoelectric composite film, resulting in a 5-fold enhancement of the strain-induced piezo potential and a 15-fold amplification of the output current. This highly-efficient PENG achieved a peak output power density of 10 µW/cm2 and enabled to run a self-powered integrated wireless electronic node (SIWEN). The PENG was applied to real-life scenarios including wireless data communication, efficient energy harvesting from automobile vibrations as well as biomechanical motion. This low-temperature, full-solution synthesis approach could lead to a paradigm shift in sustainable power sources, expanding the realms of flexible PENGs. One of the remaining concerns is the highly soluble lead component, which is one of the constituents of the PENGs that poses potential adversary impacts on human health and the environment. To address this concern, lead-free organic-inorganic hybrid perovskite (OIHP) based flexible piezoelectric nanogenerators (PENGs) have been developed. The excellent piezoelectric properties of the FASnBr3 NPs was demonstrated with a high piezoelectric charge coefficient (d33) of ~ 50 pm/V through piezoelectric force microscopy (PFM) measurements. The device’s outstanding flexibility and uniform distribution properties resulted in a maximum piezoelectric peak-to-peak output voltage of 94.5 V, peak-to-peak current of 19.1 μA, and output power density of 18.95 μW/cm2 with a small force of 4.2 N, outperforming many state-of-the-art halide perovskite-based PENGs. For the first time, a self-powered RF wireless communication between smartphones and a nanogenerator solely based on a lead-free PENG was demonstrated and serves as a stepping-stone towards achieving self-powered Internet of Things (IoT) devices using environment-friendly perovskite piezoelectric materials. Likewise, triboelectric nanogenerators (TENGs) are also promising energy-harvesting devices for powering the next generation of wireless electronics. TENGs’ performance relies on the triboelectric effect between the tribonegative and tribopositive layers. In this study, a natural wood-derived lignocellulosic nanofibrils (LCNF) tribolayer was reported to have high tribonegativity (higher than polytetrafluoroethylene (PTFE)) due to the presence of natural lignin on its surface and its nanofibril morphology. LCNF nanopaper-based TENGs produced significantly higher voltage (160%) and current (120%) output than TENGs with PTFE as the tribonegative material. Assembling LCNF nanopaper into a cascade TENG generated sufficient output to power a wireless communication node to send a radio-frequency signal to a smartphone every 3 mins. This study demonstrates the potential of using LCNF as a more environmentally friendly alternative to conventional tribonegative materials based on fluorine-containing petroleum-based polymers. Overall, this thesis explores the design and development of highly efficient and flexible nanogenerators for self-powered wireless electronics. By combining highly electroactive nanomaterials with flexible polymer matrix structures, NGs with high electric output performance and flexibility were successfully obtained. The synthesizing process for the electroactive nanomaterials was carefully designed and adopted to sustain the inherent advantages of flexible electronics. The various type of high performance flexible NGs developed in this research work, including ZnO/PVDF porous PENGs, FAPbBr2I/PVDF based PENGs, FASnBr3/PDMS based PENGs, and LCNF nanopaper-based TENGs, provide promising solutions for energy harvesting and self-powered sensing

Proceedings of the 2018 Canadian Society for Mechanical Engineering (CSME) International Congress

Published proceedings of the 2018 Canadian Society for Mechanical Engineering (CSME) International Congress, hosted by York University, 27-30 May 2018