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Textile-based thermoelectric (TE) devices are being investigated to power smart textiles autonomously. While previous research has focused on a solid system where the required junctions are fabricated into the device, there has been limited attention given to replacing these TE systems reliably. This work looks at a newer approach to the construction and demonstration of a wearable thermoelectric structure that employs three-dimensional knitted spacers to increase the temperature difference where the TE junctions are detachable and disposable. This system features positive and negative junctions which can be removed while maintaining its excellent voltage generation in low ΔT and good Seebeck coefficients. A mathematical model simulates the potential energy outputs and maximum power points generated, which can be used to increase the device's performance for future wearable sensing applications. [ABSTRACT FROM AUTHOR]

Tin dioxide (SnO2) is an important transparent conductive oxide (TCO), highly desirable for its use in various technologies due to its earth abundance and non-toxicity. It is studied for applications such as photocatalysis, energy harvesting, energy storage, LEDs, and photovoltaics as an electron transport layer. Elemental doping has been an established method to tune its band gap, increase conductivity, passivate defects, etc. In this study, we apply density functional theory (DFT) calculations to examine the electronic and optical properties of SnO2 when doped with members of the oxygen family, namely S, Se, and Te. By calculating defect formation energies, we find that S doping is energetically favourable in the oxygen substitutional position, whereas Se and Te prefer the Sn substitutional site. We show that S and Se substitutional doping leads to near gap states and can be an effective way to reduce the band gap, which results in an increased absorbance in the optical part of the spectrum, leading to improved photocatalytic activity, whereas Te doping results in several mid-gap states. [ABSTRACT FROM AUTHOR]

Triboelectric nanogenerator (TENG) cathodic protection technology based on new energy harvesting represents a promising strategy owing to the low cost, low environmental pollution and simple installation. However, converting alternating current to pulsed direct current through a rectifier reduces the cathodic protection efficiency. Here, a multi-phase coupling TENG (RD-TENG) energy harvesting device with rotating disc is proposed for metal cathode anticorrosion. Through the rotation of the disk, high density current is generated to form a DC power supply. The current output pulse interval is reduced after full wave rectification, and the effect of a constant and stable direct current (DC) power supply can be achieved. The highly coupled superposition RD-TENG (3P5E) demonstrates a short-circuit current density (Isc) of 1.86 μA, an open circuit voltage (Voc) of 120 V, and a transferred charge (Qsc) of 50 nC. At low speeds, RD-TENG (3P5E) can effectively power up to six LED bulbs without any noticeable flickering. Furthermore, when 304 SS connected to RD-TENG (3P5E), the open circuit voltage and corrosion potential decreased by 102 mV and 122 mV respectively, indicating superior corrosion protection compared to systems without RD-TENG. In general, this advancement provides an important practical significance for TENGs in expanding the application of cathodic corrosion protection in the Marine industry. [ABSTRACT FROM AUTHOR]

The self-excited oscillation system, owing to its capability of harvesting environmental energy, exhibits immense potential in diverse fields, such as micromachines, biomedicine, communications, and construction, with its adaptability, efficiency, and sustainability being highly regarded. Despite the current interest in track sliders in self-vibrating systems, LCE fiber-propelled track sliders face significant limitations in two-dime nsional movement, especially self-rotation, necessitating the development of more flexible and mobile designs. In this paper, we design a spatial slider system which ensures the self-rotation of the slider propelled by a light-fueled LCE fiber on a rigid circular track. A nonlinear dynamic model is introduced to analyze the system's dynamic behaviors. The numerical simulations reveal a smooth transition from the static to self-rotating states, supported by ambient illumination. Quantitative analysis shows that increased light intensity, the contraction coefficient, and the elastic coefficient enhance the self-rotating frequency, while more damping decreases it. The track radius exhibits a non-monotonic effect. The initial tangential velocity has no impact. The reliable self-rotating performance under steady light suggests potential applications in periodic motion-demanding fields, especially in the construction industry where energy dissipation and utilization are of utmost urgency. Furthermore, this spatial slider system possesses the ability to rotate and self-vibrate, and it is capable of being adapted to other non-circular curved tracks, thereby highlighting its flexibility and multi-use capabilities. [ABSTRACT FROM AUTHOR]

With the rise of demand for smart wearable and flexible electronic devices in the modern world, high‐performance hybrid mechanical energy harvesters (HMEHs), which can easily convert biomechanical energy into electricity for powering a variety of portable electronic gadgets and operating smart sensors, have gained extensive interest. Herein, propose piezo/ferroelectric and dielectric niobium (Nb)‐doped bismuth titanate (Bi4Ti3‐xNbxO12, NBTO) plates, are proposed and synthesized by a molten‐salt synthesis technique, and they are further embedded into the poly(vinylidene fluoride‐co‐hexafluoropropylene) (NBTO/PVDF‐HFP) flexible composite film (CF) to construct a flexible HMEH. The prepared NBTO/PVDF‐HFP CFs reveal good piezo/ferroelectricity, β‐phase fraction, and dielectric properties, which can improve the electrical output performance of the HMEH. The 2 wt.% NBTO/PVDF‐HFP CF‐based HMEH exhibits high and stable electrical performance of ≈175 V, ≈5.8 µA, ≈76 µC m−2, and ≈2.02 W m−2, respectively. Furthermore, the durability and mechanical robustness analysis of the HMEH is conducted for several days. The real‐time applications of the HMEH are demonstrated by harvesting the biomechanical energy obtained from daily human activities and powering various portable electronics. Also, the HMEH integrated with an Arduino microcontroller unit is employed as a smart sensor switch for implementing smart home/building stair‐sensing applications and sending emergency e‐mail alerts. [ABSTRACT FROM AUTHOR]

Developing mechanical energy harvesters for electrical stimulation (ES) needed to augment cell behavior is a burgeoning area of interest. Mechanical energy harvesters that can generate electrical energy in electrolyte‐containing aqueous environments offer a unique solution for delivering ES to cells. In this work, a fully integrated ES assembly (FESA) is introduced that comprises coiled polydopamine (PDA) containing carbon nanotube yarn (CNT) harvesters, serving as ES generators, and poly(3,4‐ethylenedioxythiophene) coated carbon nanotube (PEDOT/CNT) sheets employed as a conductive scaffold. The PDA containing CNT (PDA/CNT) yarn, a novel twistron electrode, achieves an enhanced electrical power at a lower matching impedance than coiled CNT yarn to efficiently transfer ES to the conductive scaffold. The PEDOT used for the scaffold provides a suitable surface for cell adhesion and low resistance for effective ES transmission. In addition, the upscaled array of coiled PDA/CNT yarns provides an ES current density range up to 75.4 µA cm−2, which is much higher than for ES systems using different mechanical energy harvesters. This FESA is designed to provide an optimal level of ES for the proliferation and differentiation of chondrocytes. The findings illuminate the potential of chemically modified twistron energy harvesters as an innovative and effective strategy to promote biological response. [ABSTRACT FROM AUTHOR]

Due to their distinctive security characteristics, all-solid-state batteries are seen as a potential technology for the upcoming era of energy storage. The flexibility of nanomaterials shows enormous potential for the advancement of all-solid-state batteries' exceptional power and energy storage capacities. These batteries might be applied in many areas such as large-scale energy storage for power grids, as well as in the creation of foldable and flexible electronics, and portable gadgets. The most difficult aspect of creating a comprehensive nanoscale all-solid-state battery assembly is the task of decreasing the particle size of the solid electrolyte while maintaining its excellent ionic conductivity. Materials possessing nanoscale structural features and a substantial electrochemically active surface area have the potential to significantly enhance power characteristics and the cycle life. This might bring about substantial changes to existing energy storage models. The primary objective of this research is to summarize the latest advancements in utilizing nanomaterials for energy harvesting in various all-solid-state battery assemblies. This study examines the most complex solid–solid interfaces of all-solid-state batteries, as well as feasible methods for implementing nanomaterials in such interfaces. Currently, there is significant attention on the necessity to develop electrode–solid electrolyte interfaces that exhibit nanoscale particle articulation and other characteristics related to the behavior of lithium ions. [ABSTRACT FROM AUTHOR]

A novel wave energy harvester (WEH) that can recover energy in the direction of heave, sway, and surge is designed under the background of low recovery efficiency and complex installation of the existing wave energy harvester. The harvester consisted of four main components: energy input module, energy transfer module, energy conversion module, and energy store module. In the paper, to convert more wave energy into electrical energy and improve the energy conversion efficiency of WEH, the motion transfer module is divided into vertical and horizontal motion transfer modules, which are used to harvest vertical and horizontal wave energy, respectively. The vertical motion transfer module combined with the ball screw structure, planetary gear structure, and one-way gear units ensure the generator has high speed. The horizontal motion transfer module is mainly composed of three uniformly distributed one-way gear units, ensuring collect the wave energy in all horizontal directions. The dynamic model of the harvester is established, and the simulation experiment is carried out under wave conditions with periods of 2 s, 2.5 s, and 3 s, respectively. The simulation results show that when the wave period is 2 s, 2.5 s, and 3 s, the corresponding energy conversion efficiency of the WEH is 66.7%, 60.9%, and 57.1%, respectively. The proposed study provides a theoretical reference for modeling similar WEHs and can effectively balance energy supply and demand and further support the global agenda of UN-2030 for sustainable development, especially SDG-7. [ABSTRACT FROM AUTHOR]

Flexible electronic components such as wearable sensors, energy harvesting devices, and human health monitoring systems based on piezoelectric materials have garnered significant attention within the scientific community. In this study, PZT nanofibers were modified with dopamine hydrochloride prior to their integration into PVDF fibers, serving as piezoelectric reinforcements to enhance the mechanical and piezoelectric characteristics of composite fiber films. Subsequently, a facile hot-pressing method was employed to fabricate multilayered films characterized by a densely packed surface fiber arrangement and a loosely organized internal fiber orientation, which markedly improved the self-supporting ability and fiber density of the electrospun fiber films. A detailed investigation into the micro-morphology, crystallinity, and enhanced piezoelectric properties of the films was conducted. Notably, the composite fiber film containing 6 wt% PZT NFs exhibited a peak piezoelectric coefficient (d 33) of 29 pC/N, resulting in an output voltage of 13.8 V. This represents a 2.23-fold enhancement in d 33 value and a 4.6-fold increase in output voltage when compared to the pristine PVDF fiber film, which had a d 33 of 13 pC/N and an output voltage of 3 V. The power density achieved by the sensor is 0.73 μW/cm2. This performance is underpinned by a high piezoelectric coefficient, outstanding output characteristics, and robust stability, which collectively enhance the sensor's efficacy in various applications. This research presents an effective approach for augmenting the piezoelectric performance of PVDF-based composite films and paves the way for the advancement of piezoelectric energy harvesting applications. [ABSTRACT FROM AUTHOR]

Flexible piezoelectric ceramic composites (FPCCs) hold promising applications in fields such as flexible sensing and energy harvesting. However, the previous methods are difficult to achieve high-precision preparation of the FPCCs with complex structures, as well as the synergistic enhancement of piezoelectric performance and flexibility. In this study, by configuring a flexible resin matrix and employing a surface functionalization treatment on the piezoelectric ceramic particles, the flexibility and piezoelectric performance of the FPCCs are synergistically improved. Moreover, the addition of a light absorber, TiO 2 , significantly improves the 3D printing precision. The mechanical properties, piezoelectric performance, and printing precision of the FPCCs are analyzed. It is found that the printing error is less than 2 μm, the tensile fracture strength is 4.07 MPa, the elongation at break is 350 %, and the piezoelectric constant d 33 can reach 7.7 pC/N. In addition, the cyclic loading tests show that FPCCs with high-precision 3D complex microstructure have good recovery performance. This study not only enriches the formulation of FPCCs slurry for 3D printing, but also provides a research foundation for the multifunctional applications. [ABSTRACT FROM AUTHOR]

The study employed the water-based casting technique to prepare BST sheets, which were then combined with PDMS to BST composite sheets for wind energy harvesting. By adding 0.3–1.2 mol% Y 2 O 3 as an additive, the dielectric constant and the flexoelectric coefficient of the BST sheets were significantly enhanced. The Y 2 O 3 and BST powders were mixed to form a casting slurry with the appropriate viscosity, which was then cast into a sheet. After the sintering process, silver electrodes were coated on both surfaces of the sheet. To enhance the flexibility of the sheet, PDMS was applied to the silver-coated surfaces, creating a "sandwich structure" composite sheet. The flexoelectric properties of the composite sheets are characterized utilized the micro cantilever beam method. The energy harvesting experiments, conducted in a simulated wind tunnel environment, demonstrate that the composite sheets exhibit varying flexoelectric properties and energy conversion efficiencies, depending on their thickness. When the doping amount of Y 2 O 3 is 0.6mol%, the composite sheets with a BST layer thickness of 200 μm exhibit the highest flexoelectric coefficient of 1.1 μC/m; the composite sheets with a BST layer thickness of 100 μm exhibit the strongest current output capability of 4.2 nA. These findings indicate that the developed composite sheets could be promising for applications in renewable energy harvesting, particularly for capturing and converting wind energy into useable electrical power. [ABSTRACT FROM AUTHOR]

Near‐Infrared (NIR) phosphorescence at room temperature is challenging to achieve for organic molecules due to negligible spin–orbit coupling and a low energy gap leading to fast non‐radiative transitions. Here, we show a supramolecular host–guest strategy to harvest the energy from the low‐lying triplet state of C64 nanographene tetraimide 1. 1H NMR and X‐ray analysis confirmed the 1 : 2 stoichiometric binding of a Pt(II) porphyrin on the two π‐surfaces of 1. While the free 1 does not show emission in the NIR, the host–guest complex solution shows NIR phosphorescence at 77 K. Further, between 860–1100 nm, room temperature NIR phosphorescence (λmax=900 nm, τavg=142 μs) was observed for a solid‐state sample drop‐casted from a preformed complex in solution. Theoretical calculations reveal a non‐zero spin–orbit coupling between isoenergetic S1 and T3 of π‐stacked [1 ⋅ Pt(II) porphyrin] complex. External heavy‐atom‐induced spin–orbit coupling along with rigidification and protection from oxygen in the solid‐state promotes both the intersystem crossing from the first excited singlet state into the triplet manifold and the NIR phosphorescence from the lowest triplet state of 1. [ABSTRACT FROM AUTHOR]

AbstractVortex-bladeless wind power generators are revolutionary concepts that use wind vortex-induced vibration to generate electricity through oscillation and vibration. This unique approach allows for a simpler design, environmental friendliness, on-site production, and lower initial costs than traditional wind turbines. This article presents a vibration analysis on the rod of a vortex bladeless wind power generator for a sandwich Timoshenko beam with various face sheets, including carbon nanotube (CNT), graphene platelets (GPL), and carbon nanorods (CNR), and cores, including positive and negative Poisson’s ratios in honeycomb structure, porous material, and metal foam. The governing equations of motion are derived using Hamilton’s principle and solved using trigonometric functions for different boundary conditions. The results of this research are compared with previous studies, and the maximum error is 3.05%. This study examined the effects of various parameters on the dimensionless natural frequencies. To obtain the highest peak amplitude for maximum energy harvesting, to choose the best rod for the bladeless wind power generator among the four types of cores and three types of factsheet layers, the honeycomb core with a positive Poisson’s ratio and the GPL-reinforced composite with the SNUPD distribution are selected because they have the most deflection. Some researchers have worked in the field of sandwich beams. Still, in this study, the main goal is to investigate the Timoshenko sandwich beam by examining all types of cores and reinforcements to increase efficiency and optimize bladeless wind generators to achieve maximum power. [ABSTRACT FROM AUTHOR]

Due to their simplicity, relatively high efficiency, and scalability, point wave energy absorbers (PWAs) have emerged as one of the most popular and promising solutions for wave energy harvesting. Their fundamental operation principle is based on activating linear resonance to pump energy from the waves to the PWA. Thus, their effective operation bandwidth is restricted to the range of incident wave frequencies that are close to the natural frequency of the PWA. This key constraint is very challenging to meet given the high stiffness of the hydrostatic buoyancy force and the variability of the wave conditions. A direct result of not meeting this constraint is a substantial reduction in the efficacy and power transduction capabilities of the PWA. To overcome this problem, deliberate introduction of nonlinearities into the PWA design has been recently proposed and exploited in two forms: (i) introduction of a nonlinear multi-stable restoring force, and (ii) introducing and/or exploiting parametric instabilities. The premise is that such approaches may be able to (i) shift the response frequency of the PWA towards the energetic low-frequency waves, and (ii) reduce the sensitivity of the PWA to the uncontrollable spatio-temporal variations in the incident waves. This review critically assesses the feasibility of leveraging nonlinear phenomena to improve the performance of PWAs. Our findings strongly point towards the conclusion that a nonlinear restoring element does not improve the capture width ratio or effective bandwidth of the PWA when compared to an optimal linear design. Furthermore, since the nonlinearity often results in aperiodic and coexisting competing responses, it adds additional layers of complexity during performance optimization and full-scale implementation. Nonetheless, the nonlinearity can be utilized as an effective means to passively shift the effective bandwidth of the PWA towards the energetic low-frequency wave content, and to decrease the sensitivity of the PWA to the wave parameters under irregular waves whose parameters drift with time. [ABSTRACT FROM AUTHOR]

The primary goal of this study is to develop and test a small-scale horizontal-axis underwater Ocean Current Turbine (OCT) by creating a mathematical model for coupled dynamics aided by a Blade Element Momentum (BEM) simulation-integrated experimental approach. This research is motivated by the urgent need for sustainable energy sources and the vast potential of ocean currents. By integrating mathematical modeling with the experimental testing of scaled model OCTs, this study aims to evaluate performance accurately. The experimental setup involves encapsulating a 3D-printed turbine model within a watertight nacelle which is equipped with sensors for comprehensive data recording during towing tank tests. Through these experiments, we seek to establish correlations between the generated power, force, and rotational speed of the turbine's Permanent Magnet DC (PMDC) motor, which determines the turbine's capability to extract dynamic energy inflow. Moreover, this research aims to provide valuable insights into the accuracy and applicability of theoretical predictions in real-world scenarios by comparing the experimental results with BEM simulations. This combined approach not only advances our understanding of hydrokinetic energy conversion, but also contributes to the development of reliable and efficient renewable energy technologies that address global energy challenges while mitigating environmental impacts. [ABSTRACT FROM AUTHOR]

In this investigation, a magnetically coupled double-spring design is presented for harvesting low-level non-stationary random vibrational energy. The sensor relies on multimodal coupling between the translation and rotation of a two-spring magnet and coil system to widen the harvesting bandwidth. Energy methods are used to develop a model to characterize the electromechanical response of the system, the solution of which is obtained using stochastic techniques based on a particle swarm algorithm. This approach provides an efficient method to estimate system parameters that otherwise are difficult or impossible to determine with independent measurements. The experimental results demonstrate agreement with the theoretical predictions over a limited bandwidth. The sensor can effectively harvest non-stationary vibration energy down to 10−4 g within a limited bandwidth of 130–150 Hz. The sensor prototype has an operational volume of 2.6 c m 3 with a calculated power density of 0.2 W / c m 3 . The sensor's small size results in a coupling efficiency of approximately 6% across the tested bandwidth. [ABSTRACT FROM AUTHOR]

The results of measurements of the efficiency of energy harvesting from commonly available general-purpose telecommunications systems, divided into typical bands available under European conditions, have been presented in this paper. Specially designed harvesters were used, dedicated to powering autonomous semi-passive Radio Frequency Identification (RFID) tags. For the assumed resistive loads, the achievable output voltage values of the harvesters were measured across a wide spectrum of electromagnetic field strengths, simulating real conditions. The performance and dynamics of the energy storage process with fixed parameters were studied at an intermediate stage, before the energy conditioning process. The harvesters were treated as typical energy sources with unknown but variable parameters, so their dynamic parameters and instantaneous energy supply were also analyzed. These activities will enable the final development of a power supply system with parameters acceptable for the planned applications and whose efficiency will be maximized under the given conditions. For this purpose, the energy harvesting systems were designed, a suitable laboratory stand was built, and the elaborated circuits were measured to determine the expected parameters of energy harvesting. [ABSTRACT FROM AUTHOR]

This paper proposes a microwave rectifier designed for the popular 5G band, featuring impedance dispersion compensation and a cross-type impedance matching network. The rectifier has an ultra-high power conversion efficiency. The compensation network employs two parallel transmission lines to counteract the nonlinear shift of the diode input impedance caused by frequency variation. Additionally, the cross-over impedance matching network enhances matching and minimizes losses. After rigorous theoretical analysis and simulation, the rectifier is fabricated. Experimental results show significant conversion efficiency in the 5G band (across 4–6.5 GHz). At an input power of 12 dBm, the rectifier achieves more than 60% efficiency between 4.8 and 6.4 GHz and more than 70% between 5.2 and 6.2 GHz, with a peak efficiency of 78.1%. Moreover, the rectifier maintains more than 50% efficiency over a wide input power range of 5 to 14 dBm. [ABSTRACT FROM AUTHOR]

Sustainable and environment‐friendly polymer composite smart paints/coatings with polyurethane (PU) derived from castor‐oil (CO) as the matrix and barium titanate (BTO) microparticles as piezo‐active inclusions (2, 4, 6, 8, and 10 vol.%) have been prepared employing ultrasonication and solvent casting, followed by contact DC poling method. Relative dielectric constants varied from 5.26 ± 0.37 for pristine COPU to 8.9 ± 0.36 for COPU/10 vol.% BTO composite, at a frequency of 1 kHz. Piezoelectric strain constant d33 of the poled films varied from 0.0 pC/N for pristine castor‐oil based polyurethane (COPU) to 1.2 pC/N for COPU/10 vol.% BTO (CPBT‐5) composite. Tensile tests showed that the elastic modulus varied from 1.98 ± 0.003 MPa for pristine COPU to 5.13 ± 0.02 MPa for COPU/10 vol.% BTO composite. Dynamic mechanical analysis confirmed the viscoelastic nature of the smart paints. Measurement of current–voltage response under different compressive loads indicates that COPU/10 vol.% BTO composite can generate a current of ~28 nA and voltage of ~8 V under a dynamic compressive load of 40 N, applied at a frequency of 1 Hz. These experiments were complemented by Fourier transform infra‐red spectroscopy and scanning electron microscopy. In addition, finite element analyses based on periodic boundary conditions have been performed to predict the effective electro‐elastic properties of these piezoelectric smart composite coatings. Highlights: Castor‐oil‐based PU piezoelectric composites with BTO inclusions were developed.Increase in BTO content up to 10 vol.% increases dielectric constant by ~1.7 times.COPU/BTO composites exhibit significantly increased piezoelectric response.Elastic and viscoelastic properties are also enhanced with increasing BTO content.Finite element models show a good match with experimental results. [ABSTRACT FROM AUTHOR]

Solar energy holds promise as a sustainable and environmentally friendly source of power. In this study, we focus on improving the thermal efficiency of parabolic trough solar collectors (PTSCs) by investigating the performance of three different binary micropolar nanofluids – micropolar‐Casson, micropolar‐Maxwell, and micropolar‐Williamson – when used as heat transfer fluids within these collectors, with engine oil as the base fluid. The problem studied revolves around enhancing the heat transfer characteristics within PTSCs, crucial for maximizing energy conversion efficiency in solar power generation. By exploring the behavior of these nanofluids under various flow conditions, we aim to optimize the design and operation of PTSC systems for improved performance and sustainability. The importance of this research lies in its potential to significantly enhance the efficiency of solar energy harvesting, thereby contributing to the transition toward cleaner energy sources and reducing dependence on fossil fuels. Additionally, the findings have implications for diverse applications, including solar aviation, solar‐powered maritime vessels, solar thermal power plants, industrial process heating, and solar‐driven water pumping mechanisms, where improved heat transfer efficiency is paramount for enhancing overall system performance and reducing operational costs. Furthermore, the investigation delves into the influence of various factors governing the flow of these binary micropolar nanofluids within PTSC setups, including aspects such as velocity, thermal characteristics, entropy generation, skin friction, drag force, and local Nusselt number. The results notably reveal substantial enhancements in thermal efficiency, with maximal relative enhancements quantified as 22.1768%, 19.3662%, and 17.7349% for micropolar‐Casson, micropolar‐Maxwell, and micropolar‐Williamson nanofluids, respectively. [ABSTRACT FROM AUTHOR]

Triboelectric nanogenerators (TENGs) have emerged as promising portable and sustainable energy sources in daily life, harvesting energy from human motion, water, and wind. However, they still face limitations in aspects such as contact area, deformability, wettability, and manufacturing method. Here, a wearable TENG incorporating an anisotropic domino structure based on a fluorinated elastomer blend is presented. Because of its thin, elongated structure with broad sides, the TENG achieves substantially larger contact areas and high bendability. Introducing a fluorinated elastomer into the polydimethylsiloxane matrix via a simple blending process not only enhances the triboelectric performance but also reduces surface energy and improves the stretchability of elastomers. The anisotropic arrangement of dominoes, in synergy with the fluorinated elastomer, mimics the surface physicochemical properties of natural rice leaves, resulting in anisotropic superhydrophobic wetting behavior with a self‐cleaning effect and controlled directional water flow for efficient water energy harvesting. Therefore, the TENG functions as an energy‐harvesting leaf that captures energy from wind and water droplets, as well as a wearable energy‐harvesting wristband that generates power from human motions such as touching, shaking, and hand washing. [ABSTRACT FROM AUTHOR]

In light of the crucial role of marine ecosystems and the escalating environmental conservation challenges, it is essential to conduct marine monitoring to help implement targeted environmental protection measures efficiently. Energy harvesting technologies, particularly triboelectric nanogenerators (TENGs), have great potential for prolonging the lifespan and enhancing the reliability of sensors in remote areas. However, the high internal resistance, low current, and friction-induced abrasion issues of TENGs limit their performance in practical applications. This work presents a rolling mode triboelectric nanogenerator that utilizes multi-tunnel grating electrodes and the opposite-charge-enhancement mechanism to harvest wave energy efficiently. The device achieves significant instantaneous and root mean square power density of 185.4 W/(m3·Hz) and 10.92 W/(m3·Hz), respectively. By utilizing stacked devices and an exclusively designed power management module, a self-powered ocean sensing system including computing and long-range wireless communication (0.8 km) capabilities was developed. Laboratory and in-situ ocean tests were conducted to assess and validate the system. This work offers a potential solution for the challenging deployment of marine self-powered sensing nodes. Limited current output hinders triboelectric nanogenerators for maritime applications. Authors design a rolling-mode TENG with multi-tunnel grating electrodes, achieving 185.4 W/(m3·Hz) power density. They demonstrate a self-powered ocean sensing system for water quality monitoring and wireless communication. [ABSTRACT FROM AUTHOR]

Plants and animals produce highly evolved, hierarchical systems that combine physicochemical material parameters with functional micro‐ and nanostructures to manage energy, motion, and species survival. These systems, besides providing cues on bottom‐up manufacturing of technological structures, can give insight on strategies for efficient energy management. Here is reported the observation of an optically interconnected network formed by the cells of the leaves of the Macodes petola jewel orchid that provides light harvesting and redistribution across its surface. The planar redistribution of light incident on the leaf is enabled by the distinctively rounded shape of the outer epidermal cells and by their arrangement in a short‐range ordered hexagonal lattice. Successful replication of a live leaf in a free‐standing biopolymer film validates the observation and opens avenues for the exploration of non‐traditional energy harvesting interfaces that are soft, conformal, and curvilinear. [ABSTRACT FROM AUTHOR]

The shift from traditional bulky electronics to smart wearable devices represents a crucial trend in technological advancement. In recent years, the focus has intensified on harnessing thermal and mechanical energy from human activities to power small wearable electronics. This vision has attracted considerable attention from researchers, with an emphasis on the development of suitable materials that can efficiently convert human body energy into usable electrical form. Metal–organic frameworks (MOFs), with their unique tunable structures, large surface areas, and high porosity, emerge as a promising material category for human body energy harvesting due to their ability to be precisely engineered at the molecular level, which allows for the optimization of their properties to suit specific energy harvesting needs. This article explores the progressive development of MOF materials, highlighting their potential in the realm of self-power devices for wearable applications. It first introduces the typical energy harvesting routes that are particularly suitable for harvesting human body energy, including thermoelectric, triboelectric, and piezoelectric techniques. Then, it delves into various research advances that have demonstrated the efficacy of MOFs in capturing and converting body-generated energy into electrical energy, emphasizing on the conceptual design, device fabrication, and applications in medical health monitoring, human–computer interaction, and motion monitoring. Furthermore, it discusses potential future directions for research in MOF-based self-powered devices and outlines perspectives that could drive breakthroughs in the efficiency and practicality of these devices. [ABSTRACT FROM AUTHOR]

AbstractTo automate the approach of assessing the health and efficacy of large structural systems globally through structural health monitoring systems, a vast network of sensors that must be mounted throughout the entire structure and connected to a continuous power supply is necessary. Clusters of wires need to be placed throughout the structures to support the network, or batteries must be changed frequently, adding to the network’s high maintenance expenses. The present study investigates the scope of powering such low-energy devices with a localized renewable energy source based on smart piezoelectric components such as PZT-patched energy harvesting systems. This paper analyses the performance of the PZT patch mounted on different structures that are predominantly activated in d31 mode. A vibration testing rig is manufactured to perform experiments for investigating the effect of material properties, natural frequencies, vibrating structural mass, and their interaction with the output power of a PZT transducer. Optimal mass, material, and structural configurations are attempted to be identified experimentally. The hypothesis, predictions, and results are evaluated further based on a converged finite element model. Subsequently, we introduce a novel concept of chiral fractal substrates in piezoelectric energy harvesters, wherein a significant improvement is noticed in the energy output along with increased frequency-band programmability. The power output of such architected and optimized energy harvesters holds the potential to serve as a reliable and sustainable alternative to conventional batteries, effectively providing a renewable source of power to energize and sustain low-power micro-electro-mechanical systems (MEMS) and devices. [ABSTRACT FROM AUTHOR]

Magneto‐mechano‐electric (MME) energy harvesters (EHs) have emerged as a promising solution for powering Internet of Things (IoT) sensor networks by capturing ambient stray magnetic fields in urban circumstance. Despite significant advancements, achieving milliwatt‐level power generation from extremely weak (<1 Oe) and randomly oriented magnetic fields remains challenging. Drawing inspiration from the configuration of cross‐shaped spider legs, this study introduces an innovative X‐shaped MME‐EH featuring fourfold symmetric architecture with symmetrically distributed magnets at each end, enabling near‐isotropic in‐plane omnidirectional energy harvesting. Under extremely weak magnetic fields 0.75 and 0.3 Oe at 60 Hz, the device achieves a record‐high output power of 7.31 and 1.67 mWRMS, respectively, representing a 362% improvement in normalized power over the state‐of‐the‐art results. The theoretical model attributes these gains to the synergistic enhancement effect of the second bending mode and the dual‐mode structure, collectively improving both magnetomechanical and electromechanical coupling by augmenting the magnetic moments and suppressing the clamp loss. The device further demonstrates robust real‐world applications, efficiently powering a wireless IoT sensor system by harvesting multidirectional magnetic field energy from household appliances. This work opens new avenues for developing efficient multimodal MME‐EHs capable of harnessing omnidirectional, weak magnetic fields for widespread IoT applications. [ABSTRACT FROM AUTHOR]

Photocatalysis is a zero-carbon route for energy generation by scavenging photon energy from sunlight to convert renewable feedstock into hydrogen gas. Photocatalytic reaction relies on semiconductor performances to absorb photons and generates photoinduced electron and hole pairs. This review analyses recent studies on synthesis methods and modification strategies of g-C 3 N 4 to improve hydrogen production, emphasizing the effect of surface area, crystallinity, band gap energy, and electron-hole pairs separation and transfer. The effect of precursor and synthesis temperature of g-C 3 N 4 synthesized using the pyrolysis method is discussed in developing polymeric g-C 3 N 4 structures, encompassing the type of solvent, temperature, and the use of catalysts. Structural modification of g-C 3 N 4 via heat treatment, exfoliation, protonation, and ionic solvent methods aim to improve the crystallinity and surface area while optimizing the structural defect is also reviewed. Modification of electronic properties is divided into metal impregnation - generated Schottky junction and surface plasmon resonance effect, metal and non-metal doping, and heterojunction formation to improve the absorption in the visible light region, separation and transfer of electron-hole pairs. The mechanism of heterojunction is also discussed to provide details on the transfer and separation process of photogenerated charge carriers. [ABSTRACT FROM AUTHOR]

Flexoelectricity is the universal electric polarization of dielectrics upon exertion of a non‐uniform strain gradient. With the advancement of nano‐technology and miniaturization of electronic devices, flexoelectricity holds the promise to address the power requirements for such device operation. The direct flexoelectric effect in liquid crystal (LC) embedded poly(vinylidene fluoride) (PVDF) polymer films is examined for the first time by the application of external strain on the films. Physical characterizations such as Differential Scanning Calorimetry (DSC), dielectric spectroscopy, X‐ray diffraction, and field emission scanning electron microscopy (FESEM) are carried out to study the composite films' intrinsic and extrinsic properties like dielectric, crystallinity, and morphologies. The value of the flexoelectric coefficient (μ12) increases with the concentration of LC incorporation. At 3 wt%, μ12 attains a maximum value of 68 nC m−1, which is more than a threefold increase compared to that of the pure PVDF film. The role of Maxwell–Wagner–Sillars (MWS) polarization in determining flexoelectric polarization in polymer composites is also discussed. Moreover, the influence of the microstructure and domain size formation in determining the flexoelectric response are discussed in detail to infer the behavior of the flexoelectric coefficients of the films. Potential device applications based on this phenomenon have been proposed for future research in sensing and actuation. [ABSTRACT FROM AUTHOR]

Although batteries are a highly popular energy source in biosensors, batteries can be an economic limitation for low‐cost sensing applications and pose significant challenges in miniaturization, biocompatibility, and disposal. To surmount such issues, "self‐powered sensors" gain the spotlight thanks to their energy harvesting from the environment through embedded miniaturized systems. In this review, the recent developments in self‐powered devices are summarized with a specific focus on the integration of supercapacitors with sensors and biosensors. The working principles of microsupercapacitors, fabrication methods, their integration with biosensors, and their ultimate applications (i.e., biomedical monitoring and analytical biomarker detection) are described. Different energy harvesting systems are summarized and their integration with self‐powered sensors or biosensors is highlighted. The limitations and challenges of the existing approaches and the future of supercapacitor‐integrated sensing systems are also critically discussed. [ABSTRACT FROM AUTHOR]

Energy harvesting from energy sources is a rapidly developing cost-effective and sustainable technique for powering low-energy consumption devices such as wireless sensor networks, RFID, IoT devices, and wearable electronics. Although these devices consume very low average power, they require peak power bursts during the collection and transmission of data. These requirements are satisfied by the use of energy-storage devices such as batteries or supercapacitors (SCs). Batteries offer significantly higher energy density but are subject to regular replacement, thermal runaway risk, and environmental concerns. On the other hand, SCs provide over a million-fold increase in capacitance compared to a traditional capacitor of the same volume. They are considered as the energy-storing devices that bridge the gap between conventional capacitors and batteries. They also offer fast charging times, a long lifecycle, and low equivalent series resistance (ESR). Most importantly, they are capable of handling the high transient currents produced by energy harvesters and provide a stable power source for external loads. This study encompasses a brief exploration of the three fundamental SC types. Then, the discussion delves into the integration of SCs into energy harvesting applications. The collective knowledge presented aims to guide future research endeavors fostering the development of novel energy harvesting systems using SCs. [ABSTRACT FROM AUTHOR]

The need to globalize and implement the fourth industrial revolution has led to increased interest in research on renewable energy harvesting equipment. Wind and solar have been the fastest growing sources of energy and have been used to reduce our dependency on fossil fuels for energy. The Savonius wind turbine is an attractive option for regions with high turbulence intensity and low wind speeds due to its advantages over other small-scale vertical-axis wind turbines. These advantages include its simple design, satisfactory performance at lower speeds, and ability to turn independent of the wind flow direction. However, Savonius wind turbines face several challenges. The most significant one being the negative torque generated during operation. This negative torque is caused by the interaction between the exhaust air and the returning blade, thus reducing efficiency, as the turbine has to overcome this additional force. To improve on the efficiency, various assessments and optimization techniques have been employed. These focus on the geometric parameters of the Savonius wind turbine as well as installation augmentation techniques. This article reviews and reports on several combinations of parametric performance-influencing adjustments and power augmentation techniques applied to Savonius wind turbines. The article concludes by proposing future research directions. [ABSTRACT FROM AUTHOR]

In this paper, an array piezoelectric energy harvester (APEH) is designed for energy collection from water hydraulic system. The APEH is arranged in a spatial axial array, exhibiting excellent insulation and waterproof properties. The effects of connection modes and pressure pulsation parameters on the output performance of APEH are investigated through theoretical analysis, simulation and experiment. The results show that the output electric energy of each piezoelectric disk is consistent, and it is generated by the deformation caused by pressure pulsation. The connection modes show significant differences at different resistances. Series and parallel connections have the same maximum output power. The parallel connection has a smaller optimal resistance and has advantages in practical engineering applications. Both the pressure amplitude and the pulsation frequency affect the output voltage and power and increasing the pulsation frequency leads to the decrease of optimal resistance. By employing parallel connection, APEH can achieve higher output at lower load resistances. When the resistance is 12 kΩ, the average power and power density are reach as 997.63 μ W and 2.54 μ W mm−3, respectively. In summary, the APEH proposed in this paper offering a viable solution for energy recovery in water hydraulic systems and the sustainable power supply of the sensors, along with providing relevant theoretical references and practical schemes. [ABSTRACT FROM AUTHOR]

In the current electromechanical model of cantilevered piezoelectric energy harvesters, the assumption of uniform electric field strength within the piezoelectric layer is commonly made. This uniform electric field assumption seems reasonable since the piezoelectric layer looks like a parallel-plate capacitor. However, for a piezoelectric bender, the strain distribution along the thickness direction is not uniform, which means the internal electric field generated by the spontaneous polarization cannot be uniform. In the present study, a non-uniform electric field in the piezoelectric layer is resolved using electrostatic equilibrium equations. Based on these, the traditional distributed parameter electromechanical model is corrected and simplified to a practical single mode one. Compared with a traditional model adopting a uniform electric field, the bending stiffness term involved in the electromechanical governing equations is explicitly corrected. Through comparisons of predicted power output with two-dimensional finite element analysis, the results show that the present model can better predict the power output performance compared with the traditional model. It is found that the relative corrections to traditional model have nothing to do with the absolute dimensions of the harvesters, but only relate to three dimensionless parameters, i.e., the ratio of the elastic layer's to the piezoelectric layer's thickness; the ratio of the elastic modulus of the elastic layer to the piezoelectric layer; and the piezoelectric materials' electromechanical coupling coefficient squared, k 31 2 . It is also found that the upper-limit relative corrections are only related to k 31 2 , i.e., the higher k 31 2 is, the larger the upper-limit relative corrections will be. For a PZT-5 unimorph harvester, the relative corrections of bending stiffness and corresponding resonant frequency are up to 17.8% and 8.5%, respectively. An inverse problem to identify the material parameters based on experimentally obtained power output performance is also investigated. The results show that the accuracy of material parameters identification is improved when considering a non-uniform electric field. [ABSTRACT FROM AUTHOR]

The piezoelectric and flexoelectric techniques are of great interest among the scientific fraternity, especially for the design of vibration-based micro/nano energy harvesters. The development of such energy harvesters in the micro/nanoscale has a huge potential, mostly in wireless networks and IoT-based applications. The present work thus formulates novel nanostructure-based analytical models of energy harvesters with asymmetric proof mass considering nonlocal flexoelectricity, geometrical nonlinearity, mid-plane stretching, harmonic base, and axially restraint forces. Using non-classical Euler-Bernoulli nanobeam and Hamilton's principle, governing differential equation of motion has been derived. Analytical solutions have been obtained to compute the eigenfrequencies and subsequent modes of vibration concerning various systems' physical and geometric variables. Nonlinear steady-state voltage and power characteristics thereafter have been investigated and studied their local stability and bifurcation for primary and sub-harmonic resonant conditions. The influences of performance factors associated with asymmetrically proof mass, nonlocal elasticity, and time-dependent base and restraint forces on the nonlinear voltage and power output using frequency characteristics criterion. These results have been validated with the findings using COMSOL-2D, and interestingly, mean voltage and power responses from linear models are found to be highly consistent with findings in COMSOL 2D. The present outcome shows how the asymmetric proof mass and nanoscale effect create disparities in harvesting energy performance and, simultaneously, how important their role is to avoid any undesirable structural instability. The present studies together can strengthen the significance of size-dependency and asymmetric proof mass while designing a nanoscale generator in the presence of harmonic excitation. [ABSTRACT FROM AUTHOR]

This study extensively characterizes the out‐of‐plane stiffness and energy harvesting capabilities of a newly proposed anti‐trichiral hierarchical auxetic honeycomb structure, both mechanically and deformationally. By introducing a design concept based on the anti‐trichiral honeycomb (ATCH), a structure with superior out‐of‐plane load‐carrying capacity and excellent auxeticity is achieved. To validate the finite element model, compression simulations are conducted. Comparative investigations into the morphing characteristics and energy harvesting performance between the novel structure and the ATCH are performed. Additionally, the influence of various parameters on the comprehensive performance of the novel auxetic structure is explored. It has been found that the angle φ is most sensitive to the auxetic properties, while the ratio k significantly impacts energy absorption. This research advances the design of novel auxetic structures for potential applications in protective engineering. [ABSTRACT FROM AUTHOR]

Solar radiation impacts diverse aspects of city life, such as harvesting energy with PV panels, passive heating of buildings in winter, cooling the loads of air-conditioning systems in summer, and the urban microclimate. Urban digital twins and 3D city models can support solar studies in the process of urban planning and provide valuable insights for data-driven decision support. This study examines the calculation of solar incident radiation at the city scale in Sofia using remote sensing data for the large shading context in a mountainous region and 3D building data. It aims to explore the methods of geometry optimisation, limitations, and performance issues of a 3D computer-aided design (CAD) tool dedicated to small-scale solar analysis and employed at the city scale. Two cases were considered at the city and district scales, respectively. The total face count of meshes for the simulations constituted approximately 2,000,000 faces. A total of 64,379 roofs for the whole city and 4796 buildings for one district were selected. All calculations were performed in one batch and visualised in a 3D web platform. The use of a 3D CAD environment establishes a seamless process of updating 3D models and simulations, while preprocessing in Geographic Information System (GIS) ensures working with large-scale datasets. The proposed method showed a moderate computation time for both cases and could be extended to include reflected radiation and dense photogrammetric meshes in the future. [ABSTRACT FROM AUTHOR]

The application of carbon nanotube (CNT) yarns as thermoelectric materials for harvesting energy from low‐grade waste heat including that generated by the human body, is attracting considerable attention. However, the lack of efficient n‐type CNT yarns hinders their practical implementation in thermoelectric devices. This study reports efficient n‐doping of CNT yarns, employing 4‐(1, 3‐dimethyl‐2, 3‐dihydro‐1H‐benzimidazole‐2‐yl) phenyl) dimethylamine (N‐DMBI) in alternative to conventional n‐dopants, with o‐dichlorobenzene emerging as the optimal solvent. The small molecular size of N‐DMBI enables highly efficient doping within a remarkably short duration (10 s) while ensuring prolonged stability in air and at high temperature (150 °C). Furthermore, Joule annealing of the yarns significantly improves the n‐doping efficiency. Consequently, thermoelectric power factors (PFs) of 2800, 2390, and 1534 µW m−1 K−2 are achieved at 200, 150, and 30 °C, respectively. The intercalation of N‐DMBI molecules significantly suppresses the thermal conductivity, resulting in the high figure of merit (ZT) of 1.69×10−2 at 100 °C. Additionally, a π‐type thermoelectric module is successfully demonstrated incorporating both p‐ and n‐doped CNT yarns. This study offers an efficient doping strategy for achieving CNT yarns with high thermoelectric performance, contributing to the realization of lightweight and mechanically flexible CNT‐based thermoelectric devices. [ABSTRACT FROM AUTHOR]

This paper puts forward a new vertical-tunneling-attributed dual-material double-gate heterojunction-TFET (VTDMDG-HTFET). The device structure of VTDMDG-HTFET includes Si 0. 7 Ge 0. 3 material for the designing of source region. The mechanism of vertical tunneling in VTDMDG-HTFET provides superior electric field at tunneling interface and leads to improved transfer characteristics. VTDMDG-HTFET also includes metal gate work-function engineering approach to facilitate high ON-current and small OFF-current. Application of high- k dielectric material HfO˙2 in the form of gate oxide enhances the capacitive-coupling at channel-source interface. Moreover, the work includes the comparison of proposed VTDMDG-HTFET with the conventional vertical-tunneling based dual-material double-gate-TFET (VTDMDG-TFET). It has been observed from the simulation results that SiGe source-based VTDMDG-HTFET offers better DC characteristics in terms of superior ON-current, smaller OFF-current, steeper subthreshold-slope, lower threshold voltage, higher transconductance along with smaller drain-induced barrier-lowering (DIBL) effects as compared to its counterpart silicon-source-based VTDMDG-TFET. In this work, reliability of VTDMDG-HTFET has also been examined and compared with VTDMDG-TFET in terms of temperature sensitivity and effect of different interface trap charges. The device simulation and investigations have been carried out using technology computer aided design (TCAD) tool. Moreover, device circuit mixed-mode simulation analysis is carried out for conventional and proposed device based resistive load inverters. A comparison is performed between both the inverters in terms of prorogation delay and switching threshold voltages. Further, the mixed mode simulation analysis is also performed for the proposed device based inverter under the influence of different interface trap charges (ITCs). Study shows that reliability performance of the proposed device is better as compared to its counterpart conventional device. Hence, vertical tunneling and SiGe source-based VTDMDG-HTFET can be a better choice for various applications such as analog/RF, analog and digital electronic circuits, energy harvesting, gas-sensing and memory devices. [ABSTRACT FROM AUTHOR]

Vibration isolation for low frequency excitation and the power supply for low power monitoring sensors are important issues in bridge engineering. The main problem is how to effectively combine the vibration isolator with the energy harvester to form a multi-functional structure. In this paper, a system called quasi-zero stiffness energy harvesting isolator (QZS-EHI) with triple negative stiffness (TNS) is proposed. The TNS structure consists of linear springs, rigid links, sliders, and ring permanent magnets. Newton’s second law and Kirchhoff’s law construct dynamic equations of the QZS-EHI, and a comparison is made to contrast it with other QZS and linear isolators. The comparison field includes the QZS range, amplitude-frequency relationship, force transmissibility, and energy harvested power. The isolator can be applied to many engineering fields such as bridges, automobiles, and railway transportation. This paper selects bridge engineering as the main field for the dynamic analysis of this system. Considering the multi-span beam bridge, this paper compares different situations including the bridge with QZS-EHI support, with linear stiffness isolator support, and with single beam support. All results show that the QZS-EHI is not only better than the traditional isolator with linear stiffness under both harmonic and stochastic excitation, but also better than some QZS isolators with double or single negative stiffness in bridge vibration isolation and energy harvesting. Theoretical analysis is verified to correspond to the simulation analysis, which means the proposed QZS-EHI has practical application value. [ABSTRACT FROM AUTHOR]

With the gradual miniaturization of electronic devices and the increasing interest in wearable devices, flexible microelectronics is being actively studied. Owing to the limitations of existing battery systems corresponding to miniaturization, there is a need for flexible alternative power sources. Accordingly, energy harvesting from surrounding environmental systems using fluorinated polymers with piezoelectric properties has received significant attention. Among them, polyvinylidene fluoride (PVDF) and PVDF co-polymers have been researched as representative organo-piezoelectric materials because of their excellent piezoelectric properties, mechanical flexibility, thermal stability, and light weight. Electrospinning is an effective method for fabricating nanofibrous meshes with superior surface-to-volume ratios from polymer solutions. During electrospinning, the polymer solution is subjected to mechanical stretching and in situ poling, corresponding to an external strong electric field. Consequently, the fraction of the piezoelectric β-phase in PVDF can be improved by the electrospinning process, and enhanced harvesting output can be realized. An overview of electrospun piezoelectric fibrous meshes composed of PVDF or PVDF co-polymers to be utilized is presented, and the recent progress in enhancement methods for harvesting output, such as fiber alignment, doping with various nanofillers, and coaxial fibers, is discussed. Additionally, other applications of these meshes as sensors are reviewed. [ABSTRACT FROM AUTHOR]

This work aims to develop an experimental investigation into the effectiveness of the sliding-mode approach for hybrid vibration-based energy harvesting. A proposed sliding-mode triboelectric-electromagnetic-piezoelectric energy harvesting model involves a cantilever beam with a tip mass exposed to magnetic and frictional forces. The experimental findings indicate that the system can achieve its peak inter-well oscillation output within a low-frequency range of 4Hz–6Hz. Friction has a lesser impact on the open-circuit voltage output at an excitation acceleration of 1.5g compared with 1g. The distribution of tri-stability changes with the presence of friction. This model provides a deeper understanding of the influence of the dry friction coefficient (0.2–0.5) on the interactive behaviors of different generator units. [ABSTRACT FROM AUTHOR]

In recent years, significant strides have been made in the inverse design of metamaterial perfect absorbers (MPAs) using deep learning techniques. However, this progress has been hindered by the functional homogeneity arising from the structural uniformity of the inverse-designed MPAs. In this paper, we address this limitation by designing reconfigurable MPAs (RMPAs) with three distinct structures and propose a residual parallel neural network (RPNN) that incorporates the optimized residual fully connected neural network (RFC-NN) for the inverse design of multifunctional MPAs. The trained RPNN accurately predicts the structural parameters and their corresponding absorption spectra with remarkable precision, yielding R2 values of 0.9981 and 0.9928, respectively. With this model, we successfully inverted the design of MPAs with three functions: broadband absorption, dual-band absorption, and triple-band absorption properties. A particularly noteworthy achievement was the realization of absorption bandwidth shifts using liquid crystal (LC) materials. Our RPNN showcases its proficiency in designing RMPAs with multifunctionality, all within a single network model. This marks a significant advancement over previous research methodologies. The proposed methodology holds great promise in diverse applications such as solar energy harvesting, detection, and filtration. [ABSTRACT FROM AUTHOR]

This research investigates the design of a nanostructured metamaterial absorber, featuring a core composition of nickel (Ni) metallic patch surrounded by an inductive grid. The proposed Ni-based nano-absorber exhibits a remarkable absorption bandwidth, spanning both visible and short-infrared wavelengths, with an impressive average absorption efficiency of 90% from 400 to 2000 nm. This study comprehensively examines the absorption characteristics of the nano-absorber across a range of incident angles and polarization states of optical light. Notably, the absorber demonstrates a polarization-insensitive response due to the inherent four-fold symmetry within its nanoresonator design and gives a sizeable absorption for various incident angles. Furthermore, the paper also investigates the surface electric field for a deeper understanding of its performance. Additionally, an equivalent circuit model has been developed for the proposed nanostructured absorber, and a comparison between the simulated and analytical absorption shows a close agreement between them. The simple and easily fabricable design of this absorber makes it a promising candidate for diverse applications, encompassing energy harvesting, solar cells, photodetectors, etc. Furthermore, the straightforward and versatile geometry of the proposed nano-absorber can be readily adapted for use in different operating frequency spectra, including microwave and terahertz ranges. [ABSTRACT FROM AUTHOR]

Harvesting electricity from ubiquitous atmospheric moisture has drawn growing research attention. Despite great advances, moisture generators still suffer from performance decay during long‐term service. Recently, self‐oscillating actuators driven by humidity gradience have attracted great interests, which may give a clue to harvest energy persistently via electromagnetic induction. In order to combine high electric conductivity with self‐oscillating actuators, bimorph composites of 2D conductive MXene with liquid metal (i.e., EGaIn) are designed. In presence of marine alginate, EGaIn droplets can be encapsulated by MXene nanosheets in their suspension. And simple liquid‐casting can produce biomorph actuating films with top MXene‐rich layer and bottom EGaIn‐rich layer of self‐sintered EGaIn droplets. When exposing to a humidity gradience (e.g., 20% cm−1), this biomorph actuator can oscillate persistently with an actuating speed of ≈260° s−1 and a frequency of ≈0.5 Hz, while without any human intervention. Under a magnetic field (e.g., intensity ≈0.5 T), this self‐oscillating behavior can generate an alternating faradic current with an amplitude of at least 1360 µA m−2. Thus, this study may not only provide an alternative pathway for producing self‐oscillating and conductive actuators, but also offer a new strategy for persistent energy harvest from atmospheric moisture. [ABSTRACT FROM AUTHOR]

The multilayer composite film system was designed in this study. The multilayer composite film was constructed by alternating electrospinning of MXene doped with polyacrylonitrile (PAN) nanofilm and thermoplastic polyurethane (TPU) nanofilm as piezoelectric functional layer. After utilizing nanofilm material, the piezoelectric sensor was prepared and subsequently examined for its piezoelectric sensitivity, piezoelectric output, and mechanical characteristics. MXene/PAN/TPU multilayer composite films showed good piezoelectric output performance. The final experimental data showed that the piezoelectric sensor of the MXene/PAN/TPU-based system achieved 0.16 kPa−1 piezoelectric sensitivity, 150ms/140ms response time and recovery time, good output voltage and output current, and good output stability. In human biological motion detection, the generator produced a maximum output voltage of 30 V when pressed by the palm. Tests such as palm pressing, finger tapping, and footstomping demonstrated the potential of piezoelectric sensors in human energy harvesting and motion monitoring. Multilayer composite films had flexible mechanical properties and sensitive piezoelectric response and had broad application prospects in piezoelectric sensors and piezoelectric nanogenerators. [ABSTRACT FROM AUTHOR]

As the Internet of Things (IoTs) rapidly gain popularity, the demand for self-powered flexible electronic devices is continuously rising, particularly in the intelligent sports field. Hence, we introduced a silicone tube-based triboelectric nanogenerator (ST-TENG) designed for mechanical energy harvesting and tennis training monitoring. The ST-TENG, with its innovative tubular structure, effectively harvests low-frequency mechanical energy and converts it into electrical energy. At a working frequency of 6 Hz, the ST-TENG achieved an open-circuit voltage (Voc) of 122.51 V, a short-circuit current (Isc) of 15.05 µA, and a transfer charge (Qsc) of 33.74 nC. The ST-TENG demonstrates high sensitivity and accuracy in capturing subtle motion details, providing comprehensive data on various aspects of an athlete's performance. The ST-TENG demonstrated excellent responsiveness to pressure and bending, making it suitable for real-time motion monitoring in tennis. Integrating the ST-TENG into the clothing and equipment of tennis players effectively monitored wrist, waist, and foot movements, providing detailed motion data. This research paves the way for developing highly efficient, self-powered wearable sensors that can significantly enhance the accuracy and sustainability of real-time athletic training monitoring. [ABSTRACT FROM AUTHOR]

Flexible wearable intelligent monitoring devices are playing an increasingly important role in the field of smart sports. In this work, we report a fully encapsulated flexible triboelectric nanogenerator (FEF-TENG) by utilizing 3D printing technology for harvesting mechanical energy and swimming posture monitoring. Experimental results show that the open-circuit voltage (Voc), short-circuit current (Isc), and transferred charge (Qsc) of the FEF-TENG increase significantly with bending angles, reaching peak values of 78.82 V, 3.51 µA, and 31.08 nC at 90°, respectively. The FEF-TENG device can be integrated into swimming gear to monitor elbow and knee postures, demonstrating its capability for real-time bio-mechanical analysis and performance tracking. This integration of 3D printing technology and TENG design not only optimizes the structural and material properties of the device but also simplifies the manufacturing process, making it highly suitable for advanced applications in smart sports and wearable electronics. [ABSTRACT FROM AUTHOR]

This study reports the room temperature testing of an InGaAs/InP photodetector, biased under linear sweep and/or parametric bias voltage for both modulated, and unmodulated 1550 nm wavelength illuminations. Charge transport of the photo-generated carriers is probed under absorber's electric field manipulations via parametric control of applied bias, readout element, and light intensity. The device exhibits three different illumination intensity dependent current signatures. Speed of the employed device is enhanced under relatively stronger electric fields ensuring higher drift, and reduced transit times. A three order reduction in the gain setting of the readout element results in ∼ 235 times large peak-current under 20 times smaller pulsed illumination of 0.2 μ W . This electric field enhancement decreases rise, and fall times under pulsed illumination from 225 ns to 115 ns , and 1.553 μ s to 1.143 μ s , respectively. But, the large photodetection plausibility, and reduced transit times ensuring relatively fast speed comes at the expense of ~ 5 order high noise activity in the device. It is also inferred that, overall noise spectrum of the device is not decided by simple generational processes in the absorber, but through the actual proportion of photo-generated carriers taking part in the real charge transport. [ABSTRACT FROM AUTHOR]

With the development of the Internet of Things (IoT), IoT nodes with limited energy and computing capability are no longer able to address increasingly complex computational tasks. To address this issue, an Unmanned Aerial Vehicle (UAV)-assisted Wireless Power Transfer (WPT) Mobile Edge Computing (MEC) system is proposed in this study. By jointly optimizing variables such as energy harvesting time, user transmission power, user offloading time, CPU frequency, and UAV deployment location, the system aims to maximize the number of computation bits by the users. This optimization yields a challenging non-convex optimization problem. To address these issues, a two-stage alternating method based on the Lagrangian dual method and the Successive Convex Approximation (SCA) method is proposed to decompose the initial problem into two sub-problems. Firstly, the UAV position is fixed to obtain the optimal values of other variables, and then the UAV position is optimized based on the solved variables. Finally, this iterative process continues until the algorithm convergences, and the optimal solution for the given problem is obtained. The simulation results indicate that the proposed algorithm exhibits good convergence. Compared to other benchmark solutions, the proposed approach performs optimally in maximizing computation bits. [ABSTRACT FROM AUTHOR]

[Display omitted] Phase change materials (PCMs) offer significant advantages in energy conversion and storage by facilitating the storage and release of thermal energy during phase transition processes. However, challenges such as leakage during PCM phase transitions and poor light absorption properties have constrained their application in the field of photothermal energy storage. In this study, Montmorillonite (Mt) and molybdenum disulfide (MoS 2) has been used to design and synthesize hybrid aerogels (MoS 2 /Mt) boasting high mechanical strength and excellent photothermal conversion performance. These aerogels are then used to encapsulate polyethylene glycol (PEG) to prepare composite PCMs with outstanding solar-thermal conversion and storage performances. The results show that the synthesized MoS 2 /Mt-PEG composite PCMs exhibit high enthalpies of melting and solidification of 169.16 J/g and 170.78 J/g, respectively, while the aerogel supporting material has a high compressive modulus of 1.96 MPa. Moreover, the composite material displayed excellent thermal stability and leakage resistance after undergoing 30 melting-cooling cycles. Furthermore, the incorporation of MoS 2 imparted outstanding light absorption properties to the MoS 2 /Mt-PEG composite, resulting in a high light absorption and photothermal conversion-storage efficiency of 93.4 % and 96.47 %, respectively. Synthesized composite PCMs also demonstrate outstanding performance in solar-thermal-electricity conversion, achieving a voltage output of 458 mV under illumination conditions and maintaining a sustainable voltage output even after removing the light source. Thus, the composite PCMs prepared in this work can meet the requirements of high enthalpy, effective leakage prevention, efficient solar-thermal conversion and solar-thermal-electricity conversion performance, thereby presenting potential applications in practical solar energy collection, conversion, and storage. [ABSTRACT FROM AUTHOR]