Energy Harvesting System Research Articles

An ultraflexible energy harvesting-storage system for wearable applications

The swift progress in wearable technology has accentuated the need for flexible power systems. Such systems are anticipated to exhibit high efficiency, robust durability, consistent power output, and the potential for effortless integration. Integrating ultraflexible energy harvesters and energy storage devices to form an autonomous, efficient, and mechanically compliant power system remains a significant challenge. In this work, we report a 90 µm-thick energy harvesting and storage system (FEHSS) consisting of high-performance organic photovoltaics and zinc-ion batteries within an ultraflexible configuration. With a power conversion efficiency surpassing 16%, power output exceeding 10 mW cm–2, and an energy density beyond 5.82 mWh cm–2, the FEHSS can be tailored to meet the power demands of wearable sensors and gadgets. Without cumbersome and rigid components, FEHSS shows immense potential as a versatile power source to advance wearable electronics and contribute toward a sustainable future.

Efficient rectifier with wide input power range for 5G applications

This article presents three efficient rectifiers for radio frequency energy harvest-ing (RFEH) systems operating at the fifth generation (5G) band (3.5 GHz). Eachrectifier operates at various input power levels (high, low, and across a widepower range). The high and low-power rectifiers feature a single serial topologyusing HSMS-2860 and SMS-7630 Schottky diodes, respectively, along with mi-crostrip lines to implement the input and output filters and the impedance match-ing network. At an radio frequency (RF) power level of 15 dBm, the high-powerrectifier harvests 67.4% to direct current (DC) power with a 300Ωload resistorand an output voltage of 2.5V. The low-power rectifier achieves its maximumpower conversion efficiency (PCE) at -2 dBm, reaching 45% efficiency with a1200Ωload. The rectifier with a extended input power range comprises twobranches of subrectifiers functioning at both high and low power levels. De-pending on the power level, the considered subrectifier harvests radio frequencypower into DC power, while the other subrectifier is deactivated. Across a powerspan of 32.5 dB (ranging from -13 to 19.5 dBm), the rectifier maintains an effi-ciency above 30%. The proposed rectifiers are efficient and suitable for imple-mentation in 5G-enabled RFEH systems.

AoI-aware transmission control in real-time mmwave energy harvesting systems: a risk-sensitive reinforcement learning approach

The evolution of enabling technologies in wireless communications has paved the way for supporting novel applications with more demanding QoS requirements, but at the cost of increasing the complexity of optimizing the digital communication chain. In particular, Millimeter Wave (mmWave) communications provide an abundance of bandwidth, and energy harvesting supplies the network with a continual source of energy to facilitate self-sustainability; however, harnessing these technologies is challenging due to the stochastic dynamics of the mmWave channel as well as the random sporadic nature of the harvested energy. In this paper, we aim at the dynamic optimization of update transmissions in mmWave energy harvesting systems in terms of Age of Information (AoI). AoI has recently been introduced to quantify information freshness and is a more stringent QoS metric compared to conventional delay and throughput. However, most prior art has only addressed average-based AoI metrics, which can be insufficient to capture the occurrence of rare but high-impact freshness violation events in time-critical scenarios. We formulate a control problem that aims to minimize the long-term entropic risk measure of AoI samples by configuring the “sense & transmit” of updates. Due to the high complexity of the exponential cost function, we reformulate the problem with an approximated mean-variance risk measure as the new objective. Under unknown system statistics, we propose a two-timescale model-free risk-sensitive reinforcement learning algorithm to compute a control policy that adapts to the trio of channel, energy, and AoI states. We evaluate the efficiency of the proposed scheme through extensive simulations.

Design and Development of an Unmanned/Autonomous Ocean Surface Vehicle using Self-Sustaining Dual Renewable Energy Harvesting System

Design and Development of an Unmanned/Autonomous Ocean Surface Vehicle using Self-Sustaining Dual Renewable Energy Harvesting System

A light-fueled self-rolling unicycle with a liquid crystal elastomer rod engine

Active materials hold substantial potential for self-sustaining motion, however, the dependency on movable light or extensive area illumination in current structures often restricts the design and practical deployment of such active machines. In this study, we report a novel zero-energy-mode, self-rolling unicycle equipped with a liquid crystal elastomer rod engine, which fueled by a fixed, small-area light source. By employing an elaborate dynamic model for liquid crystal elastomer, we derive the lateral curvature of the liquid crystal elastomer rod and the driving moment necessary for the unicycle's self-rolling. The study results demonstrate that the self-rolling of the unicycle is driven by a moment induced by the shift in the center of gravity of the curved liquid crystal elastomer rod. Our numerical simulations indicate the presence of a supercritical Hopf bifurcation point delineating the transition between the self-rolling mode and the static mode within the unicycle system. Additionally, the rolling velocity of the unicycle relies on a handful of key system parameters, notably including light intensity, light penetration depth, length of the liquid crystal elastomer rod, rolling friction coefficient, total mass of the unicycle, and wheel radius of the unicycle. The experimental validation of a self-rolling unicycle with zero-energy-mode has been conducted. The self-rolling unicycle constructed in this paper has excellent characteristics of simple structure, zero-energy-mode, horizontal constant light source, and small area light source, providing valuable insights for the utilization of photoresponsive liquid crystal elastomer rods in soft robotics, medical devices, energy harvesting systems, and actuators.

Ge quantum well channel P-MOSFET for 2.45 GHz wireless weak energy harvesting

Wireless energy harvesting is an important application of microwave wireless energy transmission system, but due to the weak energy of RF signals in the 2.45 GHz band, its rectification efficiency is not ideal. As one of the core rectifier components of wireless weak energy harvesting system, the performance of MOSFET determines the rectification efficiency of the system, and its optimized design to improve the rectification efficiency is an important direction of current research in the field. In view of this, this paper proposes and designs Ge quantum well channel PMOS for wireless weak energy harvesting at 2.45 GHz, aiming to improve the rectification efficiency of wireless weak energy harvesting systems. Starting from adjusting the structural physical parameters of the MOS tubes, the absolute value of the threshold voltage is reduced in the weak energy density region, which in turn improves the rectification efficiency of the device. Then, the novel diode connection with the introduction of substrate bias effect is compared with the conventional connection using an ADS simulation circuit, and the simulation results show that the leakage current is smaller and the rectification efficiency is higher under the novel connection. On this basis, a Ge quantum well channel PMOS device is proposed. Compared with the Ge surface channel, the hole mobility of the quantum well channel will be greatly improved, and its rectification efficiency can also be improved. The device is connected to the rectifier circuit with a novel connection and simulated using Silvaco's Mixedmode module. The results show that the rectification efficiencies of the Ge quantum well channel MOS reach 13.53 % and 32 % at low input powers of −20.34 dBm and −6.28 dBm, respectively, which are 3.3 and 1.14 times higher than those of the conventional surface channel MOS.

Design and optimization of piezoelectric energy harvesting systems for enhanced performance in wireless sensor networks

Design and optimization of piezoelectric energy harvesting systems for enhanced performance in wireless sensor networks

Design and analysis of a machine learning-optimized multi-layered absorber for renewable energy applications

Harvesting solar energy into other useful energy sources are essential now a days, hance there are many systems available for that, such as solar absorbers, solar PV, etc. In this study, we have investigated four different solar absorber designs. Out of that four, the Hash-Shaped Solar Absorber (HSSA) structure is more effective for absorbing solar radiation and converting it into heat energy. With the broad response range this structure absorb more than 90 % of the radiation in observed range (100–5000 nm). The HSSA structure demonstrates absorption > 99 % at specific wavelength peaks, including 170 nm, 550 nm, 1790 nm, 2750 nm, 3090 nm, and 3700 nm within the solar spectrum. With this the HSSA structure is having more than 93 % absorption in the 3000–4000 nm range, whereas more than 97 % absorption is achieved in the visible region. Further, the HSSA structure is treated with the Machine Learning model as the parameter optimization. The greatest R2 value for this structure is 0.999592with a test size of 0.25, and the mean squared error is 1.79801 × 10−4. The ML reduces time (takes ¼ of the traditional time) and other simulation requirements. Additionally, the structure is polarization insensitive and up to 60° incident angle insensitive. Due tothese characteristics, the HSSA structures find usage in variousapplications, including solar thermal energy harvesting systems, plasmonic sensors, and detectors.

Pendulum-based hybrid system for multidirectional energy harvesting

Pendulum-based hybrid system for multidirectional energy harvesting

Effect of scandium concentration on the performances of cantilever based AlN unimorph piezoelectric energy harvester with silicon nitride substrate

Microelectromechanical systems (MEMS) offer its ability to sense, control and actuate on sub-micron scale and exhibit its effect on macro scale. To implement any specific MEMS system, small, efficient and long-lifespan micro power sources are required. Piezoelectric energy harvester (PEH) along with radioactive source is one of the most promising approaches to harness electrical energy at micro to millimeter range. In this report, a scandium (Sc) doped Aluminium Nitride (AlN) unimorph piezoelectric energy harvester has been demonstrated. Unimorph piezoelectric layer is built on Silicon Nitride (Si3N4) substrate platform that act as cantilever beam and that can be vibrated by inbuilt radioactive system. In particular, Si3N4 as cantilever material and the impact of Sc doping concentration on electrical and mechanical properties of AlN piezoelectric thin film materials have been studied in MATLAB simulation platform. Results obtained from numerical study suggests that the proposed energy harvester model composed of AlScN unimorph piezoelectric (with 10% Sc doping concentration, Sc-10%) layer and Si3N4 cantilever can yield a maximum power output of ~ 19.33 μW and overall mechanical energy conversion efficiency of ~ 91.07%. These are the maximum output power and mechanical energy conversion efficiency numerically obtained from Sc doped AlN piezoelectric energy harvester systems to the best of our knowledge.

Application of Piezoelectricity on Running Tracks: A Prototype for the Realization of Sustainable and Efficient Energy

Electrical energy has become a basic necessity today. As the population increases, the amount of electricity demand is also increasing. Therefore, many innovations are needed to meet these needs. One of the innovations in energy harvesting systems is the use of piezoelectricity. This research aims to create a piezoelectric-based running track prototype to produce environmentally friendly electrical energy. The arrangement of piezoelectric sensors used in this research is a parallel circuit. The research method used is the Research and Development method. The test results on the physical activities of walking, running, and jumping show that the prototype system that has been made has worked well and produces a fairly stable electric voltage even though it is still in a small amount. the difference in activity and body weight that presses the prototype produces different electric voltages. For walking activity, the prototype is able to produce a maximum voltage output of 0.83V, running activity has a maximum output of 5.83V and the maximum voltage output of jumping activity is 7.88V. The use of energy is done by storing the energy obtained from the piezoelectric in the battery, which can later be monitored directly by the voltage sensor, bluetooth module, HC-05, and RTC module the data will be sent to the cell phone so that the piezoelectric output voltage can be recorded and monitored. The electrical energy output generated by the piezoelectric is able to charge the battery and switch on the LED light at 2.5 V.

Two orientation effects and large anisotropy of parameters in piezo-active 2–1–2 composites based on [0 1 1]-poled crystals

The results of a comparative study on piezo-active 2–1–2 composites with two ferroelectric components are discussed. The composite structure combines elements of 2–2 (laminar) and 1–3 (fibrous) connectivity patterns. The first component in each composite is domain-engineered [0 1 1]-poled single crystal with macroscopic mm2 symmetry and high piezoelectric activity. The second component is a poled ferroelectric ceramic that is represented by parallel rods in the shape of an elliptic cylinder with a large ratio of semi-axes at its base. The first orientation effect is appreciable due to rotations of the main crystallographic axes X and Y around Z || OX 3 by an angle α in each crystal layer. Rotation of the ceramic rod bases by an angle γ in a polymer medium leads to the second orientation effect in the 2–1–2 composite. The two orientation effects contribute to a large anisotropy of electromechanical coupling factors k3j∗ , energy-harvesting figures of merit (FOM) (Q3j∗)2 and modified FOM F3j∗σ for a stress-driven harvester. The large level of (Q32∗)2 , (Q33∗)2 , F32∗σ and F33∗σ (these parameters are of the order of 10−11–10−10 Pa−1) indicates that the studied composites are suitable for piezoelectric sensors, transducers and energy-harvesting systems. New m—α diagrams put forward in the present study show regions wherein the large anisotropy of the effective parameters ( |k33∗ / k3f∗|⩾5 , (Q33∗/Q3f∗ )2 ⩾10 and F33∗σ/F3f∗σ⩾10 , f = 1 and 2) is achieved when changing the volume fraction m of the single crystal and the rotation angle α. As a result, the leading role of the first orientation effect is emphasised.

Branch spiral beam harvester for uni-directional ultra-low frequency excitations

In recent years, there has been a growing interest in piezoelectric energy harvesting systems, particularly for their potential to recharge or replace batteries in energy-efficient electronic devices and wireless sensor networks. Nonetheless, the conventional linear piezoelectric energy harvesters (PEH) face limitations in ultra-low frequency vibrations (1–10 Hz) due to their narrow operating bandwidth and higher resonance frequencies. To address this, researchers explored compact shaped geometries, with spiral PEH being one such design to lower resonance frequencies by reducing structural stiffness. While trying to achieve this lower resonance frequency, spiral designs overlooked that they were spreading the stress across the structure. This was a significant drawback because it reduced the structure's ability to stress the piezoelectric transducer. The issue remains unaddressed, limiting the power generation of spiral beam harvesters. Furthermore, spiral structures also fail to broaden the operating bandwidth, posing additional constraints on their effectiveness. This study introduces a novel solution – the “branch spiral beam harvester,” combining the benefits of both spiral and branch beam designs. The integration of the branch beam concept into the spiral structure aimed to broaden the effective frequency range and establish a concentrated stress area for the placement of the piezoelectric transducer. Finite Element Analysis (FEA) was employed to assess operating bandwidth and stress distribution, while experimental studies evaluated voltage and power generation. Once the workability was confirmed, a statistical optimisation method was introduced to tailor the harvester for specific frequencies in the ultra-low frequency range. Results indicated that the branch spiral beam harvester exhibits a wider operating bandwidth with six natural frequencies in the ultra-low frequency range. It harnessed significantly higher output voltages and power compared to conventional linear PEH. This innovation presents a promising advancement in piezoelectric energy harvesting, offering improved performance without the need for proof masses or additional accessories.

A piezoelectric and electromagnetic vibration energy harvesting system based on spring pendulum structure and MPPT control

A piezoelectric and electromagnetic vibration energy harvesting system based on spring pendulum structure and MPPT control

Theoretical and experiment optimization research of a frequency up-converted piezoelectric energy harvester based on impact and magnetic force

Harvesting environmental vibrations to power electronic components is an essential approach for addressing the power supply challenge in MEMS. However, conventional vibration energy harvesting systems frequently suffer from limited frequency bandwidth and high-frequency deficiencies. This paper proposes a novel up-frequency structure for piezoelectric vibration energy harvesting (VEH) that relies on both nonlinear magnetic force and piecewise linear force. The proposed VEH’s nonlinear dynamic characteristics are analyzed theoretically, and an experimental prototype machining and vibration test platform are constructed. Theoretical and experimental results are compared and analyzed by conducting basic experiments and key parameter optimization experiments. The research results demonstrate that the proposed VEH can efficiently harvest vibration energy in low-frequency and wide-band environments. Regarding the system parameters, higher vibration acceleration results in increased output voltage and wider working frequency bandwidth. Reducing the gap distance enhances piecewise linear vibration, which broadens the working frequency bandwidth. Furthermore, the proposed VEH’s ability to harvest low-frequency vibrations can be enhanced by reducing the magnet distance, thereby reducing the linear resonance frequency of the system. The findings of this study offer valuable insights for advancing the engineering application of MEMS self-power supply technology.

A theoretical characterization of osmotic power generation in nanofluidic systems

Water desalination and fluid-based energy harvesting systems utilize ion-selective nanoporous materials that allow preferential transport of ions that are oppositely charged to the surface charge, resulting in the creation of an electrical current. The resultant current forms due to a potential drop or a concentration gradient (or both) applied across the system. These systems are electrically characterized by their current-voltage, I−V\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$I-V$$\\end{document}, response. In particular, there are three primary characteristics: the ohmic conductance, GOhmic=I/V\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${G}_{{{{{\\rm{Ohmic}}}}}}=I/V$$\\end{document}, the zero-voltage current, IV=0\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${I}_{V=0}$$\\end{document}, and the zero-current voltage, VI=0\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${V}_{I=0}$$\\end{document}. To date, there is no known self-consistent theory for these characteristics. Here, we present simple self-consistent expressions for each of these characteristics that provide remarkable insights into the underlying physics of water desalination and energy harvesting systems. These insights can be used to interpret (and reinterpret) the numerical and experimental measurements of any nanofluidic system subject to an arbitrary concentration gradient as well as improve their design.

Multifunctional Aspects of Mechanical and Electromechanical Properties of Composites Based on Silicone Rubber for Piezoelectric Energy Harvesting Systems.

Energy harvesting systems fabricated from rubber composite materials are promising due to their ability to produce green energy with no environmental pollution. Thus, the present work investigated energy harvesting through piezoelectricity using rubber composites. These composites were fabricated by mixing titanium carbide (TiC) and molybdenum disulfide (MoS2) as reinforcing and electrically conductive fillers into a silicone rubber matrix. Excellent mechanical and electromechanical properties were produced by these composites. For example, the compressive modulus was 1.55 ± 0.08 MPa (control) and increased to 1.95 ± 0.07 MPa (6 phr or per hundred parts of rubber of TiC) and 2.02 ± 0.09 MPa (6 phr of MoS2). Similarly, the stretchability was 133 ± 7% (control) and increased to 153 ± 9% (6 phr of TiC) and 165 ± 12% (6 phr of MoS2). The reinforcing efficiency (R.E.) and reinforcing factor (R.F.) were also determined theoretically. These results agree well with those of the mechanical property tests and thus validate the experimental work. Finally, the electromechanical tests showed that at 30% strain, the output voltage was 3.5 mV (6 phr of TiC) and 6.7 mV (6 phr of MoS2). Overall, the results show that TiC and MoS2 added to silicone rubber lead to robust and versatile composite materials. These composite materials can be useful in achieving higher energy generation, high stretchability, and optimum stiffness and are in line with existing theoretical models.

Variable-Length Pendulum-Based Mechatronic Systems for Energy Harvesting: A Review of Dynamic Models

The ability to power low-power devices and sensors has drawn a great deal of interest to energy harvesting from ambient vibrations. The application of variable-length pendulum systems in conjunction with piezoelectric or electromagnetic energy-harvesting devices is examined in this thorough analysis. Because of their changeable length, such pendulums may effectively convert mechanical vibrations into electrical energy. This study covers these energy-harvesting systems’ basic theories, design concerns, modeling methods, and performance optimization strategies. This article reviews several studies that look at dynamic models, the effects of damping coefficients, device designs, and excitation parameters on energy output. The advantages and disadvantages of piezoelectric and electromagnetic coupling techniques are demonstrated by comparative research. This review also looks at technical advances and future research prospects in variable-length, pendulum-based energy harvesting. An expanded model for an energy harvester based on a variable-length pendulum derived from the modified, swinging Atwood machine is more specifically presented. This model’s numerical simulations, estimated current and voltage outputs, and produced power from the electromagnetic and piezoelectric devices integrated at various points in a 4-DOF variable-length pendulum model all indicate encouraging results. This necessitates extra study, changes, and optimizations to improve the usefulness of the proposed model. Finally, important dynamic models on developing variable-length, pendulum-based energy harvesters for usage in a range of applications to create sustainable energy are summarized.

A semi-analytical electromechanical model for energy harvesting of plate with acoustic black hole indentations

Acoustic black hole (ABH) has been proved to be helpful for the energy harvesting of beam. Since thin plates are more widely used in practical engineering, it is of great significance to explore the energy harvesting with ABH effect applying to thin plate. Therefore, a piezoelectric plate with ABH indentations is designed and a standard full-wave rectifier circuit connected to the energy harvester in this paper. A semi-analytical electromechanical model is proposed for the energy harvesting system and Gaussian basis functions are used to solve the coupled electromechanical equations. The harvested power is calculated with the proposed method and the acceptable accuracy could be found through the validation against finite element simulation. Finally, a comprehensive analysis has been performed and numerical results show the system parameters (such as piezoelectric layer parameters, ABH parameters, and circuit parameters) have a significant influence on the energy harvesting.

A Magnetically Coupled Piezoelectric Ocean Wave Energy Harvester for Self-Powered Low-Power Appliances

The ocean contains abundant wave energy, which can be used as a new regenerative energy for power generation and provide energy for self-powered low-power appliances, realizing in situ energy utilization. Then, it can effectively promote the sustainable development strategy of the ocean and bring huge energy and social and environmental benefits. This paper proposes a magnetically coupled piezoelectric ocean wave energy harvester (MPWEH) system for wave energy harvesting. The MPWEH system includes four modules: energy harvesting, force magnification, piezoelectric power generation, and energy storage module. The energy harvesting module moves up and down in the tube body with the wave, effectively capturing and absorbing the wave energy and transforming the harvesting module’s motion into the interaction repulsive force between magnets. Then, the force magnification module amplified the magnetic force and applied it to the polarization direction of the piezoelectric ceramic to self-power the low-power appliances. This research carried out the feasibility verification experiment with the MPWEH prototype, and the results show that when the period is 3[Formula: see text]s, and the amplitude is 2[Formula: see text]m, the maximum voltage can reach 15[Formula: see text]V, and the maximum power can reach 12.85[Formula: see text]mW. Take Jiaozhou Bay Bridge as an example. The MPWEH system’s energy harvesting potential is studied, and the annual power generation of all the acquisition devices can reach 55.72[Formula: see text]kWh, which can be enough energy to supply the sensors on the cross-sea bridge.