Power Harvesting Research Articles

A 2.4 GHz High-Efficiency Rectifier Circuit for Ambient Low Electromagnetic Power Harvesting

A novel 2.4 GHz high-efficiency rectifier circuit suitable for working under very-low-input electromagnetic (EM) power conditions (−20 to −10 dBm) is proposed for typical indoor power harvesting. The circuit features a SMS7630 Schottky diode in a series with a voltage booster circuit at the front end and a direct-current (DC)-pass filter at the back end. The voltage booster circuit consists of an asymmetric coupled transmission line (CTL) and a high-impedance microstrip line (of 100 Ω instead of 50 Ω) to significantly increase the potential at the diode’s input, thereby enabling the diode to operate effectively even in very-low-power environments. The experimental measurements show that the microwave direct-current (MW-DC) conversion efficiency of the rectifier circuit reaches 31.1% at a −20 dBm input power and 62.4% at a −10 dBm input power, representing a 7.4% improvement compared to that of the state of the art. Furthermore, the rectifier circuit successfully shifts the input power level corresponding to the peak rectification efficiency from 0 dBm down to −10 dBm. This design is a promising candidate for powering low-energy wireless sensors in typical indoor environments (e.g., the home or office) with low EM energy density.

Machine Learnable Language for the Chemical Space of Nanopores Enables Structure-Property Relationships in Nanoporous 2D Materials.

The synthesis of nanoporous two-dimensional (2D) materials has revolutionized fields such as membrane separations, DNA sequencing, and osmotic power harvesting. Nanopores in 2D materials significantly modulate their optoelectronic, magnetic, and barrier properties. However, the large number of possible nanopore isomers makes their study onerous, while the lack of machine-learnable representations stymies progress toward structure-property relationships. Here, we develop a language for nanopores in 2D materials, called STring Representation Of Nanopore Geometry (STRONG), that opens the field of 2D nanopore informatics. We show that STRONGs are naturally suited for machine learning via recurrent neural networks, predicting formation energies/times of arbitrary nanopores and transport barriers for CO2, N2, and O2 gas molecules, enabling structure-property relationships. The machine learning models enable the discovery of specific nanopore topologies to separate CO2/N2, O2/CO2, and O2/N2 gas mixtures with high selectivity ratios. We also enable the rapid enumeration of unique configurations of stable, functionalized nanopores in 2D materials via STRONGs, allowing systematic searching of the vast chemical space of nanopores. Using the STRONGs approach, we find that a mix of hydrogen and quinone functionalization results in the most stable functionalized nanopore configuration in graphene, a discovery made feasible by expedited chemical space exploration. Additionally, we also unravel the STRONGs approach as ∼1000 times faster than graph theory algorithms to distinguish nanopore shapes. These advances in the language-based representation of 2D nanopores will accelerate the tailored design of nanoporous materials.

Harvesting multidirectional wind energy based on flow-induced vibration triboelectric nanogenerator with directional tuning mechanism

Wind-induced vibration (WIV), as low-velocity wind energy utilization technology in agricultural environment, has significant advantages. Nevertheless, there is a mismatch between the variability of wind direction and the work mode of triboelectric nanogenerator (TENG), which leads to a sharp decline in the performance of triboelectric power generation. This work proposes a TENG based on multidirectional WIV (TENG-WIV), which mainly contains triboelectric power generation unit, guide-wing and triboelectric direction sensor. By introducing the directional tuning mechanism based on guide-wing, the TENG-WIV aims to break the constraints of single wind direction response and effectively respond to the wind direction within 360° range, thereby realizing multidirectional wind energy harvesting and sensor power supply. The empirical findings indicate that the output voltage and current of triboelectric power generation unit are in the ranges of 62–241 V and 0.25–1.21 μA, respectively, at the wind velocities of 1.23–5.13 m/s. At a wind velocity of 3.18 m/s, the unit achieves an out-power peak of 0.09 mW. Furthermore, the triboelectric direction sensor can respond to changes in 8 directions and has wind direction monitoring potentiality. The directional tuning mechanism endows flow-induced vibration energy harvesters with an all-around multidirectional sensitivity.

Upgrading Sustainable Pipeline Monitoring with Piezoelectric Energy Harvesting

This study presents the design and implementation of a piezoelectric power harvesting device to capture vibrational energy from pipelines to self-powered IoT devices. The device utilizes key components along with the PPA-1001 piezoelectric sensor, the STM32F103C8T6 microcontroller, and LTC-3588 energy harvesting power supply. Experimental results verified the system’s performance in harvesting power within a specific frequency range of 10 Hz to 50 Hz, with the foremost overall performance at 30 Hz. The device generated the highest voltage of 3.3 V, delivering a power output of 2.18 mW, which is sufficient to power low-power electronic devices. The device maintained solid performance across a temperature range of 40 °C to 50 °C, underscoring its robustness in various environmental situations. The findings highlight the capacity of this form of generation to offer a sustainable power source for remote pipeline tracking, contributing to stronger protection and operational efficiency.

A piezoelectric acoustic black hole absorber for rail vibration reduction and energy harvesting: Semi-analytical model

Theoretically, vibration energy can be converted and harvested during the process of vibration reduction, thus enabling a self-powered supply for sensor nodes. However, little research was reported on rail absorbers that combine vibration reduction and energy harvesting. Accordingly, this study aims to design an absorber based on the acoustic black hole (ABH) effect, termed the P-ABH absorber, that can simultaneously achieve broadband vibration reduction and energy harvesting. Firstly, the P-ABH absorber was preliminarily designed, and the semi-analytical model of the track with the P-ABH absorber was established by the Rayleigh-Ritz method. Secondly, the semi-analytical model was verified by the 3D finite element method, and the vibration reduction and energy harvesting performance were initially evaluated. The dimensions of the ABH structure, along with the sizes of the piezoelectric patches, were then determined. Finally, the vibration reduction and energy harvesting performances of the P-ABH absorbers fully deployed between each fastener were evaluated. The results demonstrated that the P-ABH absorber exhibited a wider vibration reduction bandwidth than the uniform piezoelectric absorber and the piezoelectric patches, with an increase in energy harvesting power by 27.47 % and 115.26 %, respectively. The vibration reduction and energy harvesting performance were significantly affected by the number of piezoelectric patches but little affected by the thickness and total length. When the P-ABH absorbers were fully attached to the rail, the overall mean square velocities at the three resonant frequencies, which required emphatic control, were reduced by 36.77 %, 98.37 %, and 3.52 %, respectively. Meanwhile, the energy harvesting performance was excellent. The P-ABH absorber presents a promising solution for improving the sustainability and cost-effectiveness of track systems.

Piezoelectric Scaffolds as Smart Materials for Bone Tissue Engineering.

Bone repair and regeneration require physiological cues, including mechanical, electrical, and biochemical activity. Many biomaterials have been investigated as bioactive scaffolds with excellent electrical properties. Amongst biomaterials, piezoelectric materials (PMs) are gaining attention in biomedicine, power harvesting, biomedical devices, and structural health monitoring. PMs have unique properties, such as the ability to affect physiological movements and deliver electrical stimuli to damaged bone or cells without an external power source. The crucial bone property is its piezoelectricity. Bones can generate electrical charges and potential in response to mechanical stimuli, as they influence bone growth and regeneration. Piezoelectric materials respond to human microenvironment stimuli and are an important factor in bone regeneration and repair. This manuscript is an overview of the fundamentals of the materials generating the piezoelectric effect and their influence on bone repair and regeneration. This paper focuses on the state of the art of piezoelectric materials, such as polymers, ceramics, and composites, and their application in bone tissue engineering. We present important information from the point of view of bone tissue engineering. We highlight promising upcoming approaches and new generations of piezoelectric materials.

Piezoelectric nanogenerators from sustainable biowaste source: Power harvesting and respiratory monitoring with electrospun crab shell powder-poly(vinylidene fluoride) composite nanofibers

Wearable piezoelectric nanogenerators (PENGs) are increasingly significant in healthcare and energy harvesting applications due to their ability to convert mechanical energy into electrical signals. In this study, we developed PENGs by incorporating crab shell powder (CS-NFs) into electrospun polyvinylidene fluoride (PVDF) nanofibers to enhance their piezoelectric properties. The PVDF-CS-NFs (PC-NFs) composites were evaluated for structural, thermal, and piezoelectric performance. The 1.5 wt% CS-NFs composite exhibited a notable improvement, with a maximum output voltage of 19 V under mechanical deformation, significantly higher than pristine PVDF NFs. Furthermore, the device demonstrated excellent sensitivity in real-time respiratory monitoring when applied to various body locations, including the chest, throat, and mask. Additionally, the PC-NFs-based PENGs were capable of charging a 2.2 µF capacitor to 2 V within 180 s and powering 56 LEDs. These results underscore the potential of using sustainable crab shell waste in biocompatible, eco-friendly piezoelectric devices for wearable sensors and energy harvesting applications.

A Self-Powered Enzymatic Glucose Sensor Utilizing Bimetallic Nanoparticle Composites Modified Pencil Graphite Electrodes as Cathode.

Enzymatic biofuel cells (EBFC) are promising sources of green energy owing to the benefits of using renewable biofuels, eco-friendly biocatalysts, and moderate operating conditions. In this study, a simple and effective EBFC was presented using an enzymatic composite material-based anode and a nonenzymatic bimetallic nanoparticle-based cathode respectively. The anode was constructed from a glassy carbon electrode (GCE) modified with a multi-walled carbon nanotube (MWCNT) and ferrocene (Fc) as a conductive layer coupled with the enzyme glucose oxidase (GOx) as a sensitive detection layer for glucose. A chitosan layer was also applied to the electrode as a protective layer to complete the composite anode. Chronoamperometry (CA) results show that the MWCNT-Fc-GOx/GCE electrode has a linear relationship between current and glucose concentration, which varied from 1 to 10mM. The LOD and LOQ were calculated for anode as 0.26mM and 0.87mM glucose, respectively. Also the sensitivity of the proposed sensor was calculated as 25.71 A/mM. Moreover, the studies of some potential interferants show that there is no significant interference for anode in the determination of glucose except ascorbic acid (AA), uric acid (UA), and dopamine (DA). On the other hand, the cathode consisted of a disposable pencil graphite electrode (PGE) modified with platinum-palladium bimetallic nanoparticles (Nps) which exhibit excellent conductivity and electron transfer rate for the oxygen reduction reaction (ORR). The constructed EBFC was optimized and characterized using various electroanalytical techniques. The EBFC consisting of MWCNT-Fc-GOx/GCE anode and Pt-PdNps/PGE cathode exhibits an open circuit potential of 285.0mV and a maximum power density of 32.25µWcm-2 under optimized conditions. The results show that the proposed EBFC consisting of an enzymatic composite-based anode and bimetallic nanozyme-based cathode is a unique design and a promising candidate for detecting glucose while harvesting power from glucose-containing natural or artificial fluids.

Potential of coupled array harvester in enhanced energy harvesting.

Harvesting energy from nonlinear systems has been at the centre of research in the energy harvesting community. Many such proposed systems are single nonlinear harvester. While these systems show an increase in bandwidth of harvesting frequency, overall, they are not effective enough in power generation. This article studies power harvesting and frequency bandwidth characteristics of an array of harvesters. Multiple harvesters are considered with linear and nonlinear coupling between the harvesters. The phenomena of internal resonance (IR) and stochastic resonance (SR) are reported. The IR in multiple coupled nonlinear harvesters is explored using multiple-scale analysis. A parametric study is conducted to demonstrate the effect of coupling strength, frequency mistuning, innate nonlinearity and other parameters. The parametric study helped establish effective ways to increase bandwidth. Moreover, a stochastically loaded linearly coupled bistable harvester array is numerically analysed to find the effect of coupling strength and array size on the phenomenon of SR and on the system's harvesting performance. Through these studies, the potential of multiple coupled nonlinear harvesters in enhanced energy harvesting is demonstrated under both harmonic and stochastic excitation.This article is part of the theme issue 'Celebrating the 15th anniversary of the Royal Society Newton International Fellowship'.

Reconfigurable MIMO-based self-powered battery-less light communication system

Simultaneous lightwave information and power transfer (SLIPT), co-existing with optical wireless communication, holds an enormous potential to provide continuous charging to remote Internet of Things (IoT) devices while ensuring connectivity. Combining SLIPT with an omnidirectional receiver, we can leverage a higher power budget while maintaining a stable connection, a major challenge for optical wireless communication systems. Here, we design a multiplexed SLIPT-based system comprising an array of photodetectors (PDs) arranged in a 3 × 3 configuration. The system enables decoding information from multiple light beams while simultaneously harvesting energy. The PDs can swiftly switch between photoconductive and photovoltaic modes to maximize information transfer rates and provide on-demand energy harvesting. Additionally, we investigated the ability to decode information and harvest energy with a particular quadrant set of PDs from the array, allowing beam tracking and spatial diversity. The design was explored in a smaller version for higher data rates and a bigger one for higher power harvesting. We report a self-powering device that can achieve a gross data rate of 25.7 Mbps from a single-input single-output (SISO) and an 85.2 Mbps net data rate in a multiple-input multiple-output (MIMO) configuration. Under a standard AMT1.5 illumination, the device can harvest up to 87.33 mW, around twice the power needed to maintain the entire system. Our work paves the way for deploying autonomous IoT devices in harsh environments and their potential use in space applications.

Ultrahigh-mobility microbial cytochrome nanowires generate power from humidity.

Mixed electronic-ionic conductors are crucial for various technologies, including harvesting power from humidity in a durable, self-sustainable, manner unrestricted by location or environment1,2. Biological proteins have been proposed as mixed conductors for 50 years3,4. Recently, Geobacter sulfurreducens pili filaments have been claimed to act as nanowires to generate power5,6. Here, we show that the power is generated by G. sulfurreducens-produced cytochrome OmcZ nanowires that show 20,000-fold higher electron conductivity than pili7. Remarkably, nanowires show ultrahigh electron and proton mobility (>0.25 cm2/Vs), owing to directional charge migration through seamlessly-stacked hemes and a charged, hydrogen-bonding surface, respectively. AC impedance spectroscopy and DC conductivity measurements using four-probe van der Pauw and back-gated field-effect-transistor devices reveal that humidity increases carrier mobility by 30,000-fold. Cooling halves the activation energy, thereby accelerating charge transport. Electrochemical measurements identify the voltage and mobilities required to switch pure electronic conduction to mixed conduction for power generation. The high aspect ratio (1:1000) and hydrophilic nanowire surface captures moisture efficiently to reduce oxygen reversibly, generating large potentials (>0.5 V) necessary to sustain high power. Our studies establish a new class of biologically-synthesized, low-cost and high-performance mixed-conductors and identify key design principles for improving power output using highly-tunable electronic and protein structures.

Vibration of multilayer cantilever beams towards piezoelectric power harvesters

This paper investigates the vibration characteristics of a commonly employed mechanical structure, the cantilever beam, concerning its potential for direct electricity harvesting from piezoelectric crystals. Piezoelectric materials are renowned for their ability to generate electric charges when subjected to mechanical stress. To ensure continuous current generation, these materials require sustained excitation by external forces, typically achieved through vibration. However, piezoelectric crystals lack sufficient elasticity, necessitating attachment to a structurally conducive and easily vibratable framework. The cantilever beam, renowned for its simplicity and widespread use, serves as an ideal platform for this purpose. Layers of piezoelectric material (PZT5H) are affixed to brass-based cantilever beams to create various multilayer configurations. External forces are then applied at the free end of the beam to induce vibration. Given that the harvested power from PZT5H crystals correlates with the mechanical stress they experience, achieving optimal deformation is paramount. This is accomplished by leveraging the resonance effect of vibration, wherein the vibration modes and natural frequencies of the multilayer PZT5H beams must be thoroughly characterized. To this end, numerical methods and Finite Element Analysis via Abaqus software are employed. The vibrations of the brass base layer, as well as single-sided and double-sided PZT5H beams, are analyzed across four distinct mode shapes and corresponding natural frequencies. The study culminates in a comprehensive examination of the relationship between natural frequencies and dimensional parameters of the beams. Ultimately, this research offers valuable insights into the vibration behavior of cantilever beams, laying the groundwork for the development of efficient power harvesting devices utilizing mechanical vibration sources or tailored to specific applications.

The Effect of Soaking Coconut and Atonic Water as a Growth Regulatory Substances on the Growth of Patchouli Plant Cuttings (Pogostemon cablin Benth)

Patchouli plants can be planted vegetatively, one of which is stem or branch cuttings. To multiply patchouli cuttings vegetatively, you can use coconut water and Atonik as natural growth regulators. Coconut water and Atonik are very easy to obtain and are used as natural growth regulators which can function as a plant growth booster, have harvest power, improve quality, increase plant yields, increase the photosynthesis process, increase protein synthesis and also increase the absorption of nutrients from within. The aim of this research was to determine the effect of providing appropriate growth regulators from coconut water and Atonik on the growth of patchouli plant cuttings. The place and time of this research was carried out at Los Shadows, Agronomy Laboratory, Plantation Plant Cultivation Study Program, Polytechnic Agricultural State Samarinda . This research was conducted for 4 months starting from November 2021 to February 2022. The method used was a Complete Random Treatment with 3 treatments, namely immersion using water for 10 minutes (P0), treatment using 1000 ml coconut water for 10 minutes (P1) , treatment using atonic 10 ml/ 990 ml water for 10 minutes (P2). The research results showed that the use of atonic growth regulator as a soaking agent intreatment P2 with a dose of 10 ml with a mixture of 990 ml of water and a soaking time of 10 minutes showed the success of cuttings with a greater number of shoots and roots compa.red to treatments P0 and P1. The P2 treatment showed the highest average number of shoots and roots with immersion in theatonic growth regulator with an average growth of 3.4 shoots in the first month and 8.5 in the second month, as well as an average number of roots of 9.2. beginning of planting until the end of the research. The results of the research showed that the use of the atonic soaking agent in the P2 treatment with a dose of 10 ml with a mixture of 990 ml of water and a soaking time of 10 minutes showed the success of cuttings with a greater number of shoots and roots. compared to treatments P0 and P1. The P2 treatment with atonic growth regulator soaking showed the highest average number of shoots, namely 3.4 shoots in month 1 and 8.5 shoots in month 2, 12.0 shoots. Meanwhile, the number of root was 10.4 in month 3 land.

Data-driven MPPT techniques for optimizing vehicular fuel cell performance in hybrid DC microgrid

This paper aims to apply data-driven maximum power point tracking (MPPT) techniques specifically tailored for fuel cell vehicle (FCV) supported hybrid DC microgrids to enhance the power harvesting capability of fuel cell (FC) stacks. Compared to existing MPPT techniques, the current study focuses on developing and evaluating data-driven approaches for maximum power extraction by dynamically determining the operating point of FC power sources through a Zeta converter. An in-depth analysis is conducted by considering parameters such as efficiency, tracking accuracy, response time, and robustness to variations in load demand and operating conditions. The performance results validate that the developed three-layer neural network (TNN)-based MPPT gives better performance findings than Gaussian process regression (GPR), support vector regression (SVR), decision tree regression (DTR), and bagging ensemble decision tree (BEDT). In the performance evaluation phase, a vehicular FC with a rating of 1.26 kW is designed and operated within the temperature range of 320 K to 343 K for hydrogen pressure values ranging from 1 bar to 1.8 bar. For these operational conditions, the prediction accuracy value of the proposed TNN method is 99.6% while the performance values GPR, SVR, DTR, and BEDT are 99%, 98.6%, 97.2%, and 96%. In addition, system efficiency is increased by 0.98%, 1.25%, 2.51%, and 3.02% compared to GPR, SVR, DTR, and BEDT, respectively.

Enhancing the performance of pyridyl carboxamide-N,N-dimethyl amino chalcone (PCC) as a dye sensitizer for dye-sensitized solar cells (DSSCs) through the incorporation of electron donor moieties

This study has focused on enhancing the performance of pyridyl carboxamide-N,N-dimethyl amino chalcone (PCC) as a sensitizer for dye-sensitized solar cells (DSSCs) by strategically incorporating electron donor moieties identified in a literature review. Our reviewing the previous reports highlights the pivotal role of electron donors in optimizing light harvesting, electron injection, and overall power conversion efficiency in organic dye sensitizers, particularly those following a donor-bridge-acceptor (D-π-A) architecture. The selected donor moieties, including dithieno[3,2-b:2′,3′-d]thiophene (DTT), benzodithiophene (BDT), triphenylamine (TPA), carbazole (CBZ), and triazatruxene (TAZ), are systematically introduced into the molecular structure of PCC (abbreviated as PCC-DTT, PCC-BDT, PCC-TPA, PCC-CBZ, and PCC-TAZ, respectively). The performance of these modified compounds is rigorously evaluated using density functional theory (DFT) methods. Validation results revealed that the most reliable method for PCC derivative characterization involved the combination of the functional B3PW91 with a 6-31G(d) basis set. The results indicate that the incorporation of certain donor moieties, particularly BDT, significantly enhances the electronic and optical properties of PCC, including lower HOMO energy levels, a narrow energy gap (Egap), enhanced absorption intensity, and a redshift in absorption peaks. Evaluation of photovoltaic properties including electron injection (ΔGinj), and open circuit voltage (Voc), indicated facilitating spontaneous electron injection from the dyes to the TiO2 conduction band. Notably, PCC-TAZ demonstrated the lowest electron regeneration (ΔGreg), suggesting a notable potential for efficient electron regeneration.

Resource allocation algorithm for downlink secure transmission in wireless EH cooperative networks with idle relay-assisted jamming

In wireless Energy Harvesting (EH) cooperative networks, we investigate the problem of secure energy-saving resource allocation for downlink physical layer security transmission. Initially, we establish a model for a multi-relay cooperative network incorporating wireless energy harvesting, spectrum sharing, and system power constraints, focusing on physical layer security transmission in the presence of eavesdropping nodes. In this model, the source node transmits signals while injecting Artificial Noise (AN) to mitigate eavesdropping risks, and an idle relay can act as a jamming node to assist in this process. Based on this model, we formulate an optimization problem for maximizing system secure harvesting energy efficiency, this problem integrates constraints on total power, bandwidth, and AN allocation. We proceed by conducting a mathematical analysis of the optimization problem, deriving optimal solutions for secure energy-saving resource allocation, this includes strategies for power allocation at the source and relay nodes, bandwidth allocation among relays, and power splitting for the energy harvesting node. Thus, we propose a secure resource allocation algorithm designed to maximize secure harvesting energy efficiency. Finally, We validate the correctness of the theoretical derivation through Monte Carlo simulations, discussing the impact of parameters such as legitimate channel gain, power splitting factor, and the number of relays on secure harvesting energy efficiency of the system. The simulation results show that the proposed secure energy-saving resource allocation algorithm effectively enhances the security performance of the system.

Fabrication of Electronically Conductive Protein‐Heme Nanowires for Power Harvesting (Small 29/2024)

Fabrication of Electronically Conductive Protein‐Heme Nanowires for Power Harvesting (Small 29/2024)

Novel ultrastable 2D MOF/MXene nanofluidic membrane with ultralow resistance for highly efficient osmotic power harvesting

Two-dimensional (2D) materials have shown great potential in harvesting osmotic power due to their high membrane selectivity, but the high resistance from tortuous pathways of 2D nanofluidic membranes still impedes the further improvement in output performance. Here, we report an innovative 2D MXCT (MXene/Cu-TCPP) lamellar membrane with ultralow resistance for highly efficient osmotic power generation. The incorporation of 2D Ti3C2Tx MXene with rich functional groups not only resolves the water-stability issue of 2D metal-organic framework (MOF) Cu-TCPP, but provides large surface charges for selective ion transport. The orderly sub-2 nm framework channels of Cu-TCPP provide much shorter permeation pathways for fast ion transport, thus endowing the MXCT membrane with ultralow resistance. Consequently, the MXCT membrane reaches an ultrahigh power output of ∼8.29 W/m2 by mixing seawater and river water, which is ∼275 % higher than that of the pristine MXene membrane. Additionally, it outperforms all the reported single-layer 2D nanosheet-based osmotic power generators under the same experimental conditions in terms of output power and internal resistance (9 kΩ). This work presents a reliable strategy for stabilizing 2D Cu-TCPP MOF in electrolytes, opening new avenues for designing promising 2D nanofluidic membranes for efficient blue energy harvesting and ionic devices.

Piezoelectric energy harvester for wind turbine blades based on bistable response of a composite beam in post-buckling

A bistable piezoelectric energy harvester (PEH) is presented for harvesting power from vibrations occurring at low frequencies, as is the case of wind turbine blades. The axial compressive prestress of a piezoelectric composite beam at post-buckling serves as the bistability source, leading to high mechanical to electric power conversion. An in-house harvesting circuit connected to the piezoelectric terminals is used for demonstration of its harvesting power capabilities. A finite element (FE) model is used to analyze and optimize the coupled nonlinear electromechanical response of the PEH, including structure and circuit. A physical prototype has been manufactured and tested for validation of the electromechanical design and the FE modeling approach. Predictions and measurements indicate an increase of harvested power with applied prestress up to a transition point, where a sudden drop in power occurs. Good comparison between numerical and experimental results verified the modeling approach, whereas deviations related to physical boundary conditions at large compressive forces affected the prediction of the transition point in harvested power. The harvester produced 1.32 mW of electrical power under tonal base excitation of 1 g at 8 Hz. Hence, the nonlinear PEH has demonstrated its capability to harvest energy at frequencies much lower than its first linear modal frequency and could thus serve as a promising solution for powering IoT devices and sensors in large vibrating structures.

Micro-electricity generation from wind-induced vibration with magnetostrictive material-based energy harvester

This study aimed to experimentally investigate flow-induced vibration of modified circular cylinders for wind-receiving mast of Vibration-Based Power Generator (VBPG). Specifically, it focused on vibration characteristics of tapered and stepped circular cylinders in VBPG mechanism. Tapering and inverting cylinder model proved effective in reducing Vortex-Induced Vibration (VIV) onset and peak amplitude concerning flow stream velocity. Some tapered cylinder models showed a broadening peak response (upper branch region), showing an extensive power harvesting range for VBPG device. The result showed that the maximum power harvesting of the model with a plain bluff cylinder was 8.45 mW, reduced by tapering bluff cylinder. The power coefficient of VBPG with a normal bluff cylinder was 4 %, but inversing stepped bluff cylinder yielded 5.45 %. It is related to VIV-onset parameter, which was lower than that the plain cylinder. In addition, it was discovered that there was an interdependency between frequency response and power generation capacity for VIV-type resonance. The generated power proved sufficient to illuminate a board with 54 LED lamps in a laboratory-scale test. Meanwhile, an outdoor performance test of harvester, conducted with variable wind speed (0 – 3.2 m/s), showcased the reliability of VBPG mechanism for independent power supply to wireless, remote sensor networks, or moderate scale of power supply. The field test model worked not only in variable wind speed, but also in chaotic wind direction.