Transmissive Labyrinthine Acoustic Metamaterial‐Based Holography for Extraordinary Energy Harvesting

Conventional energy sources are continuously depleting, and the world is actively seeking new green and efficient energy solutions. Enormous amounts of acoustic energy are dissipated daily, but the low intensity and limited efficiency of current harvesting techniques are preventing its adoption as a ubiquitous method of power generation. Herein, a strategic solution to increase acoustic energy harvesting efficiency using a specially designed metamaterial is implemented. A scalable transmissive labyrinthine acoustic metamaterial (LAM) is designed, developed, and employed to maximize ultrasound (40 kHz) capture over its large surface area (>27 k mm2), which is focused onto a piezoelectric film (78.6 mm2), thus magnifying incident sound pressure by 13.6 times. Three different piezoelectric films – two commercial and one lab-made nanocomposite film are tested with LAM in the acoustic energy harvesting system. An extraordinary voltage gain of 157–173% and a maximum power gain of 272% using the LAM compared to the case without the LAM are achieved. Multipoint focusing using holographic techniques, showcasing acoustic patterning to allow on-demand simultaneous harvesting in separate locations, is demonstrated. Our versatile approach for high-intensity acoustic energy harvesting opens future opportunities to exploit sound energy as a resource to contribute toward global sustainability

Hot pressed K0.5Na0.5nbo3 material for piezoelectric transformer for energy harvesting

An optimized method of vibration Energy Harvesting is based on a step-down transformer that regulates the power flow from the piezoelectric element to the desired electronic load. Taking into account parameters of the whole system, the “optimal” voltage gain the piezoelectric transformer can be determined where the harvested power is maximized for the actual level of mechanical excitation. Consequently the piezoelectric transformers can be used to boost up the conversion of mechanical strain into electrical power with considerable potential in Energy Harvesting applications. Nowadays however, the most important factor is usage of lead free material for its construction. Additional desired parameters of such ceramics include high value of piezoelectric coefficients, low dielectric losses and reasonable power density. This work for first time proposes a lead free K0.5Na0.5NbO3 (KNN) material implementation for stack type of piezoelectric transformer that is designed for load efficiency optimization of vibration energy harvester

Available Technologies and Commercial Devices to Harvest Energy by Human Trampling in Smart Flooring Systems: a Review

Technological innovation has increased the global demand for electrical power and energy. Accordingly, energy harvesting has become a research area of primary interest for the scientific community and companies because it constitutes a sustainable way to collect energy from various sources. In particular, kinetic energy generated from human walking or vehicle movements on smart energy floors represents a promising research topic. This paper aims to analyze the state-of-art of smart energy harvesting floors to determine the best solution to feed a lighting system and charging columns. In particular, the fundamentals of the main harvesting mechanisms applicable in this field (i.e., piezoelectric, electromagnetic, triboelectric, and relative hybrids) are discussed. Moreover, an overview of scientific works related to energy harvesting floors is presented, focusing on the architectures of the developed tiles, the transduction mechanism, and the output performances. Finally, a survey of the commercial energy harvesting floors proposed by companies and startups is reported. From the carried-out analysis, we concluded that the piezoelectric transduction mechanism represents the optimal solution for designing smart energy floors, given their compactness, high efficiency, and absence of moving parts

A Nail-Size Piezoelectric Energy Harvesting System Integrating a MEMS Transducer and a CMOS SSHI Circuit

Piezoelectric vibration energy harvesting has drawn much interest to power distributed wireless sensor nodes for Internet of Things (IoT) applications where ambient kinetic energy is available. For certain applications, the harvesting system should be small and able to generate sufficient output power. Standard rectification topologies such as the full-bridge rectifier are typically inefficient when adapted to power conditioning from miniaturized harvesters. Therefore, active rectification circuits have been researched to improve overall power conversion efficiency, and meet both the output power and miniaturization requirements while employing a MEMS harvester. In this paper, a MEMS piezoelectric energy harvester is designed and cointegrated with an active synchronized switch harvesting on inductor (SSHI) rectification circuit designed in a CMOS process to achieve high output power for system miniaturization. The system is fully integrated on a nail-size board, which is ready to provide a stable DC power for low-power mini sensors. A MEMS energy harvester of 0.005 cm3 size, co-integrated with the CMOS conditioning circuit, outputs a peak rectified DC power of 40.6 µW and achieves a record DC power density of 8.12 mW/cm3 when compared to state-of-the-art harvesters

Energy harvesting efficiency of piezoelectric flags in axial flows

International audienceSelf-sustained oscillations resulting from fluid-solid instabilities, such as the flutter of a flexible flag in axial flow, can be used to harvest energy if one is able to convert the solid energy into electricity. Here, this is achieved using piezoelectric patches attached to the surface of the flag, which convert the solid deformation into an electric current powering purely resistive output circuits. Nonlinear numerical simulations in the slender-body limit, based on an explicit description of the coupling between the fluid-solid and electric systems, are used to determine the harvesting efficiency of the system, namely the fraction of the flow kinetic energy flux effectively used to power the output circuit, and its evolution with the system's parameters. The role of the tuning between the characteristic frequencies of the fluid-solid and electric systems is emphasized, as well as the critical impact of the piezoelectric coupling intensity. High fluid loading, classically associated with destabilization by damping, leads to greater energy harvesting, but with a weaker robustness to flow velocity fluctuations due to the sensitivity of the flapping mode selection. This suggests that a control of this mode selection by a careful design of the output circuit could provide some opportunities to improve the efficiency and robustness of the energy harvesting process

Numerical Analysis of a Roadway Piezoelectric Harvesting System

Highways, streets, bridges, and sidewalks with heavy traffic dissipate a considerable amount of waste mechanical energy every day. Piezoelectric energy harvesting devices are a very promising technology that can convert the waste mechanical energy to clean and renewable energy to enhance the sustainability of infrastructures. Research efforts in large-scale energy harvesting have led to the advancement of piezoelectric devices to the point that large-scale implementation is starting to become more feasible. The energy harvested by these devices can be used in many ways such as providing heating or cooling, melting ice, monitoring structural conditions in bridges and tunnels, and powering wireless sensors. Additionally, these devices contain an off-grid power system meaning that it has a standalone battery connected to it. This is highly beneficial in areas where city power sources are not readily available. The objective of this thesis is to study the energy harvesting potential of a dual-mode piezoelectric generator to develop a roadway piezoelectric harvesting system with ultra-high-power density and efficiency. The dual-mode harvester is made up of APC 855 with two different modes, 33-mode and 15-mode. In order to structurally optimize the design, finite element analysis was performed using ANSYS Mechanical and APDL. Static and transient simulations for each model with detailed input conditions were evaluated to determine the optimal configuration. Two different vehicle sizes were evaluated to assess the load effect on the harvested power. In addition, open circuit and closed-circuit models with different resistance values were compared to determine the resistance that produces the highest energy. Furthermore, a comparison between the different polarization directions for the 15-mode harvester was investigated to determine the optimal polarization direction

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

Fluid-solid-electric lock-in of energy-harvesting piezoelectric flags

The spontaneous flapping of a flag in a steady flow can be used to power an output circuit using piezoelectric elements positioned at its surface. Here, we study numerically the effect of inductive circuits on the dynamics of this fluid-solid-electric system and on its energy harvesting efficiency. In particular, a destabilization of the system is identified leading to energy harvesting at lower flow velocities. Also, a frequency lock-in between the flag and the circuit is shown to significantly enhance the system's harvesting efficiency. These results suggest promising efficiency enhancements of such flow energy harvesters through the output circuit optimization.Comment: 8 pages, 8 figures, to appear in Physical Review Applie

Piezoelectric wind power harnessing – an overview

As fossil energy resources deplete, wind energy gains ever more importance. Recently, piezoelectric energy harvesting methods are emerging with the advancements in piezoelectric materials and its storage elements. Piezoelectric materials can be utilized to convert kinetic energy to electrical energy. Utilization of piezoelectric wind harvesting is a rather new means to convert renewable wind energy to electricity. Piezoelectric generators are typically low cost and easy to maintain. This work illustrates an overview of piezoelectric wind harvesting technology. In wind harvesting, piezoelectric material choice is of the first order of importance. Due to their strain rate, robustness is a concern. For optimum energy harvesting efficiency resonant frequency of the selected materials and overall system configuration plays important role. In this work, existing piezoelectric wind generators are grouped and presented in following categories: leaf type, rotary type, rotary to linear type and beam type wind generators

Influence and optimization of the electrodes position in a piezoelectric energy harvesting flag

Fluttering piezoelectric plates may harvest energy from a fluid flow by converting the plate's mechanical deformation into electric energy in an output circuit. This work focuses on the influence of the arrangement of the piezoelectric electrodes along the plate's surface on the energy harvesting efficiency of the system, using a combination of experiments and numerical simulations. A weakly non-linear model of a plate in axial flow, equipped with a discrete number of piezoelectric patches is derived and confronted to experimental results. Numerical simulations are then used to optimize the position and dimensions of the piezoelectric electrodes. These optimal configurations can be understood physically in the limit of small and large electromechanical coupling.Comment: To appear in Journal of Sound and Vibratio