Energy Harvesting Ability Research Articles

Global optimization of excitation directions for scavenging energy based on a cross-jointed L-shape multidirectional piezoelectric energy harvester

Energy harvesting technology can collect energy from environmental vibrations, but it is still challenging because the vibration from an environment is random and the directions vary. In this study, a novel cross-coupled L-shaped vibration piezoelectric energy harvester (CL-VPEH) was proposed to collect energy from different environmental vibration directions. This CL-VPEH consists of a vertical beam and a horizontal beam joint crosswise with two laminated piezoelectric layers. Finite element analysis was performed to study the voltage output and resonant frequency. A simplified lumped mass model of CL-VPEH under excitation from an arbitrary direction was built to describe its working principle and multi-directional energy-harvesting ability. The experimental results demonstrate that the CL-VPEH shows good agreement with the numerical and analytical solutions. The experimental results validate the CL-VPEH’s multidirectional energy harvesting ability. Using the lumped mass model, the performance of the CL-VPEH under every single-direction excitation is investigated. A weak power output area is found with a frequency range of 10 Hz − 25 Hz, which should be avoided in future applications of this kind of multiple-directional excitation energy harvesting.

Thermally nonlinear non-Fourier piezoelectric thermoelasticity problems with temperature-dependent elastic constants and thermal conductivity and nonlinear finite element analysis

In non-isothermal conditions, numerous experimental and theoretical investigations reveal that the elastic constants and thermal conductivity in piezoelectric solids depend on temperature distribution. This work aims to investigate thermally nonlinear non-Fourier piezoelectric thermoelasticity problems with temperature-dependent elastic constants and thermal conductivity. The nonlinear time-domain finite element method is developed to directly solve nonlinear finite element governing equations, which maximally avoids the precision losses within the applications of the integrated transformation method. As a numerical example, the developed method is applied to analyze nonlinear transient thermo-electromechanical responses of a two-dimensional orthotropic piezoelectric plate of crystal class mm2. The achieved results reveal that temperature-dependent thermal conductivity and elastic constants remarkably affect the structural dynamic responses, whilst thermal wave or elastic wave will travel faster and the electrical energy harvesting ability is significantly elevated.

Codesign of Single-Layer Dual-Polarized Dual Compressed High-Order Modes Differentially Fed Patch Antenna and Solar Cells for Green Communication

A codesign dual-polarized patch antenna operating in dual compressed high-order modes and solar cells is proposed for green communication. The solar cell patch antenna is proposed for enhancing gain, wideband communication, and powering for wireless sensors. First, to enhance the gain of the antenna and the ability of optical energy harvesting, the antenna resonates at the high-order compressed modes. Second, the solar cell works in the direct-current loop, and the antenna works in the radio frequency loop separately. A differentially coupling-fed structure and two rows of vias are employed, which are beneficial to bandwidth and prevent the two loops from interfering with each other. Intrinsic isolation is achieved without any extra circuits. Next, a parametric study is exhibited as the antenna optimization guideline. By measuring the prototype experimentally performances, the design approach and the principle are validated. The measured results photoelectric experiment confirmed the ability of the solar cell antenna to convert luminous energy into electrical energy. In the desired operating band (4.8–5 GHz), the radiation performance of the proposed dual-polarized solar cell antenna is higher than 8.6 dBi for 5G communication.

Effect of harvesting module design on the thermal performance and voltage generation of a thermoelectric oscillating heat pipe

A thermoelectric oscillating heat pipe (OHP) converts a temperature potential into electricity by exploiting its internal, cyclic fluid enthalpy. In this study, the energy harvesting ability of a tubular oscillating-magnet OHP (OMHP), a type of thermoelectric OHP that utilizes a floating, cylindrical magnet and externally-wrapped solenoid, was experimentally investigated over a range of heat inputs for evaluating how harvesting module design, e.g. size of induction magnet, number of solenoids, length of module, impacts its thermal and electrical performance. Two methods for constraining/positioning the floating cylindrical magnet, i.e. with internal posts or externally-located annular magnets (for repulsive forces), were considered. While using water as a working fluid at a 75% fill ratio, results demonstrate that the OMHPs operated as a traditional OHP, with effective thermal conductivities on-the-order of 5000 W/m K, while also generating electrical voltages up to ∼250 mV (peak-to-peak). The investigated OMHPs could accommodate up to 400 W of heat transfer while maintaining an average evaporator temperature below ∼100 °C; this heat transfer limit was found to decrease substantially when using internal posts over external annular magnets for magnet positioning. However, harvester modules with internal posts were found to produce significantly more electrical voltage due to the induction magnet’s increased freedom of motion in the absence of an external magnetic field. The heat transfer and electrical voltage generation needs for a given application must be balanced and this work will aid in designing the appropriate OMHP.

Improved Energy Harvesting Ability of C3h7nh3pbi3 Decorated Pvdf Nanofiber Based Flexible Nanogenerator

Improved Energy Harvesting Ability of C3h7nh3pbi3 Decorated Pvdf Nanofiber Based Flexible Nanogenerator

Perspectives on self-powered respiration sensor based on triboelectric nanogenerator

Triboelectric nanogenerators (TENGs) have attracted widespread attention in recent years due to outstanding energy converting capability enabled by the coupling between the triboelectric effect and electrostatic induction. The excellent energy harvesting ability of TENG under low frequency and slight amplitude endows a unique superiority for self-powered respiratory detection. This Perspective systematically reviews recent progress on TENG motivated self-powered respiratory sensors. First, based on the four working modes of TENG, two types of self-powered respiratory sensors are discussed, including physical behavior monitoring and chemical reagents detection. Furthermore, the sensing mechanism, sensitive materials, device structures, and related application were comprehensively analyzed. Finally, the existing problems and development opportunities of self-powered respiration monitoring based on the triboelectric effect are interpreted in detail.

G-C3N4/Ca2Fe2O5 heterostructures for enhanced photocatalytic degradation of organic effluents under sunlight

g-C3N4/Ca2Fe2O5 heterostructures were successfully prepared by incorporating g-C3N4 into Ca2Fe2O5 (CFO). As prepared g-C3N4/CFO heterostructures were initially utilized to photodegrade organic effluent Methylene blue (MB) for optimization of photodegradation performance. 50% g-C3N4 content in CFO composition showed an enhanced photodegradation efficiency (~ 96%) over g-C3N4 (48.15%) and CFO (81.9%) due to mitigation of recombination of photogenerated charge carriers by Type-II heterojunction. The optimized composition of heterostructure was further tested for degradation of Bisphenol-A (BPA) under direct sunlight, exhibiting enhanced photodegradation efficiency of about 63.1% over g-C3N4 (17%) and CFO (45.1%). The photoelectrochemical studies at various potentials with and without light illumination showed significant improvement in photocurrent response for g-C3N4/Ca2Fe2O5 heterostructures (~ 1.9 mA) over CFO (~ 67.4 μA). These studies revealed efficient solar energy harvesting ability of g-C3N4/Ca2Fe2O5 heterostructures to be utilized for organic effluent treatment.

Self-charging power textiles integrating energy harvesting triboelectric nanogenerators with energy storage batteries/supercapacitors

Lightweight and flexible self-charging power systems with synchronous energy harvesting and energy storage abilities are highly desired in the era of the internet of things and artificial intelligences, which can provide stable, sustainable, and autonomous power sources for ubiquitous, distributed, and low-power wearable electronics. However, there is a lack of comprehensive review and challenging discussion on the state-of-the-art of the triboelectric nanogenetor (TENG)-based self-charging power textiles, which have a great possibility to become the future energy autonomy power sources. Herein, the recent progress of the self-charging power textiles hybridizing fiber/fabric based TENGs and fiber/fabric shaped batteries/supercapacitors is comprehensively summarized from the aspect of textile structural designs. Based on the current research status, the key bottlenecks and brighter prospects of self-charging power textiles are also discussed in the end. It is hoped that the summary and prospect of the latest research of self-charging power textiles can help relevant researchers accurately grasp the research progress, focus on the key scientific and technological issues, and promote further research and practical application process.

Enhancing the Electromechanical Coupling in Soft Energy Harvesters by Using Graded Dielectric Elastomers.

Soft dielectric elastomers can quickly achieve large deformations when they are subjected to electromechanical loads. They are widely used to fabricate a number of soft functional devices. However, the functions of soft devices are limited to the failure modes of soft dielectric elastomers. In this paper, we use graded dielectric elastomers to produce a soft energy harvester with a strong ability of energy harvesting. Compared to the conventional energy harvester with homogeneous dielectric films, our new energy harvester is made of graded elastomers and can increase both the specific energy from 2.70 J/g to 2.93 J/g and the maximum energy from 6.3 J/g to 8.6 J/g by just using a stiffer outer radius. By optimizing the material parameters in graded dielectric films, the soft energy harvester can reach better performance, and our results can provide guidance for designing powerful energy harvesters.

Triboelectric Nanogenerator for Ocean Wave Graded Energy Harvesting and Condition Monitoring

Using triboelectric nanogenerators (TENGs) to harvest blue energy in the ocean is advanced technology at present. In wave environments, the wave magnitude is constantly changing, so designing a TENG that can adjust the energy harvesting ability is necessary. Herein, a graded energy harvesting triboelectric nanogenerator (GEH-TENG) is fabricated, in which double generation units can operate in different transmission states to adapt to wave changes. Under small waves, the GEH-TENG is in the primary transmission state. Once waves are large enough, it enters the secondary transmission state, realizing graded energy harvesting to enhance power generation performance. Experiments show that when the input frequency is 1.0 Hz and the amplitude is 120 mm, the GEH-TENG can generate 0.7 mJ of energy in a single operation cycle, which is 2.3 times of it without grading. Moreover, it can be placed on the shore to monitor ocean wave conditions. An idea of graded energy harvesting is proposed in this study, and the proposal provides useful guidance for practical applications of TENGs in ocean wave condition monitoring.

Integration of Aperture-Coupled Multipoint Feed Patch Antenna With Solar Cells Operating at Dual Compressed High-Order Modes

This letter presents an aperture-coupled multipoint feed patch antenna integrated with solar cells capable of powering to low-power wireless sensors. Meanwhile, the solar cells as part of radiators are located at the top of the structure, improving design integration. Multipoint feed structure is employed for wideband performance. To verify the proposed solar cell antenna radiation performance and optical energy harvesting abilities, a prototype aperture-coupled multipoint feed solar cell antenna is fabricated and measured. The simulation and measurement results agree well with each other, thus, demonstrating that its total size of only 1.31 λ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> × 1.31 λ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> × 0.06 λ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> (λ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> is the free-space wavelength at the center frequency) and the antenna has achieved a stable gain varied from 9.47 to 10.85 dBi over the operating band of 4.8-5 GHz of 5G communication.

Energy-collision-aware Minimum Latency Aggregation Scheduling for Energy-harvesting Sensor Networks

The emerging energy-harvesting technology enables charging sensor batteries with renewable energy sources, which has been effectively integrated into Wireless Sensor Networks (EH-WSNs). Due to the limited energy-harvesting capacities of tiny sensors, the captured energy remains scarce and differs greatly among nodes, which makes the data aggregation scheduling problem more challenging than that in energy-abundant WSNs. In this article, we investigate the Minimum Latency Aggregation Scheduling (MLAS) problem in EH-WSNs. First, we identify a new kind of collision in EH-WSNs, named as energy-collision, and design several special structures to avoid it during data aggregation. To reduce the latency, we try to choose the parent adaptively according to nodes’ transmission tasks and energy-harvesting ability, under the consideration of collisions avoidance. By considering transmitting time, residual energy, and energy-collision, three scheduling algorithms are proposed under protocol interference model. Under physical interference model, several approximate algorithms are also designed by taking account of the interference from the nodes several hops away. Finally, the theoretical analysis and simulation results verify that the proposed algorithms have high performance in terms of latency.

Space charge induced augmented dielectric permittivity and improved energy harvesting ability of nano-Ag decorated ZnSnO3 filled PVDF based flexible nanogenerator

Here we report the effect of conducting Ag decoration on ZnSnO3 filler surface on the dielectric and mechanical energy harvesting performance of the resulting PVDF based composite films. The room temperature dielectric permittivity significantly enhanced for Ag@ZnSnO3 loaded PVDF compared to that of the ZnSnO3 loaded PVDF films through the effect of improved space charge polarization after Ag decoration on ZnSnO3 filler. The dielectric permittivity of the composite films was found to be increased gradually with the increase in the Ag concentration on ZnSnO3 filler surface. All the films exhibited low value of dielectric loss (˂0.05 at 10 kHz) which proved their good applicability in flexible dielectrics. The improved polarization enhanced the mechanical energy harvesting performance of the composite films. The output peak to peak open circuit ac voltage (VOC) for Ag@ZnSnO3-PVDF (5A10ZS) (with maximum Ag concentration on ZnSnO3 in the present experiment) film after repeated human finger tapping on it was found to be increased to ~ 20 V from a value of ~3.5 V and 11 V for neat PVDF and ZnSnO3-PVDF (5ZS) films, respectively. A 10 μF capacitor was charged to ~3.8 V dc after rectification of output VOC from 5A10ZS sample by 270 s of applied stress on it. During discharging, this dc electrical signal was able to light up some LEDs (connected in parallel) together instantaneously which proved the real life applicability of the nanogenerator device in self-powered flexible electronics.

Environment Tolerant Conductive Nanocomposite Organohydrogels as Flexible Strain Sensors and Power Sources for Sustainable Electronics

AbstractConductive hydrogels (CHs) have been highlighted in the design of flexible strain sensors and stretchable triboelectric nanogenerators (TENGs) on the basis of their excellent physicochemical properties such as large stretchability and high conductivity. Nevertheless, the incident freezing and drying behaviors of CHs by using water solvent as the dispersion medium limit their application scopes significantly. Herein, an environment tolerant and ultrastretchable organohydrogel is demonstrated by a simple solvent‐replacement strategy, in which the partial water in the as‐synthesized polyacrylamide/montmorillonite/carbon nanotubes hydrogel is replaced with the glycerol, leading to excellent temperature toleration (−60 to 60 °C) and good stability (30 days under normal environment) without sacrificing the stretchability and conductivity. The organohydrogel exhibits an ultrawide strain sensing range (0–4196%) with a high sensitivity of 8.5, enabling effective detection and discrimination of human activities that are gentle or drastic under various conditions. Furthermore, the organohydrogel is assembled in a single‐electrode TENG, which displays excellent energy harvesting ability even under a stretchability of 500% and robustness to directly power wearable electronics in harsh cold conditions. This work inspires a simple route for multifunctional organohydrogel and promises the practical application of flexible and self‐powered wearable devices in extreme environments.

Eggshell membrane and expanded polytetrafluoroethylene piezoelectric‐enhanced triboelectric bio‐nanogenerators for energy harvesting

With the growing demand for wearable electronic devices, triboelectric nanogenerators (TENGs) provide an effective solution by harvesting human body motions and converting them into electricity. Tribomaterial is one key element for the output performance and application of TENGs. In this study, biomaterial eggshell membrane (ESM) was investigated for use as a piezoelectric-enhanced positive tribomaterial. ESM not only exhibits excellent piezoelectricity due to the amount of hydrogen bonds, but it is also biocompatible and pollution free. The piezoelectricities of raw eggshell membrane (RESM), heated eggshell membrane (HESM), and carbonized eggshell membrane (CESM) were analyzed and compared. Porous expanded polytetrafluoroethylene (ePTFE) was fabricated and used as a negative tribomaterial in the TENG due to its strong electron-acquisition ability. Pairing ESM with an ePTFE resulted in a novel piezoelectric-enhanced triboelectric bio-nanogenerator (P-TENG) with an excellent energy harvesting ability, high-efficiency output performance, and sensitive human motion monitoring. By comparing ePTFE paired with RESM, HESM, and CESM, the CESM/ePTFE P-TENG showed the best output performance due to CESM's piezoelectric enhancement. This bio-P-TENG as a wearable electric device has great potential in biomedical applications.

Enhanced energy harvesting ability of polydimethylsiloxane-BaTiO3-based flexible piezoelectric nanogenerator for tactile imitation application

The development of wearable piezoelectric nanogenerator (PENG) has recently drawn extensive attention, especially in selecting lead-free piezoelectric materials with high piezoelectric coefficients. Barium Titanate (BTO) is a kind of environment-friendly piezoelectric ceramics. PENGs derived from BTO based piezo-fillers have recently attracted broad concern. However, the exploration of flexible electrodes and the application of wearable PENGs functioned with imitating tactile have usually been ignored in the pursuit of high output performance. Herein, The porous piezoelectric fillers composed of 0.82Ba(Ti0.89Sn0.11)O3-0.18(Ba0.7Ca0.3)TiO3 are prepared by a freeze-drying method, and then the polydimethylsiloxane (PDMS) is filled into the micropores of the piezoelectric ceramics, forming a distinctive 3D interconnected structure with evenly distributed inorganic piezoelectric materials. Both doping and structure modification can boost the output performance of the BTO-based PENG, from which the rational doping plays a major role in enhancing the electrical output in the current PENG system. To realize fully flexible piezoelectric nanogenerator (PENG), sliver nanowires network integrated with PDMS is adopted as the flexible electrodes, which was fabricated by the techniques combining vacuum filtration with subsequent dry transfer process. The PENG can deliver a maximum open-circuit voltage (VOC) of 39 V and short-circuit (ISC) current of 2.9 μA under a vertical force of 35 N at 2 Hz, with the maximum instantaneous power of 24.2 μW. Moreover, the device can effectively exhibit electric output signal whenever subjected to external pressing or bending stress. The output performance of the PENG at via vertical pressing stress is higher than that bending stress, which is also confirmed by COMSOL simulation. The PENG can not only be employed to harvest biomechanical energy such as digital joints movement, but also display a potential for a tactile perception. This work has established a deep association between lead-free ceramic and wearable imitated touch reception sensors by virtue of flexible PENG, which will paint a magnificent picture for flexible electronics.

Energy Efficiency Maximization for Symbiotic Radio Networks With Multiple Backscatter Devices

Driven by the limited radio spectrum resources and the high energy consumption of wireless devices, symbiotic radio (SR) has recently been proposed to support passive Internet-of-Things (IoT) networks, where a primary transmitter (PT) transmits information to a primary reader (PR), while passive backscatter devices (BDs) modulate their own information on the received primary signal and backscatter the modulated signal to the same PR by adjusting their reflection coefficients. Existing works on SR have mainly studied the case of a single BD while without considering the BD's energy harvesting (EH) ability. In this paper, we aim to maximize the energy efficiency (EE) of an SR system that includes multiple BDs each being able to harvest energy while backscattering, by jointly optimizing the PT transmission power and the BDs' reflection coefficients and time division multiple access (TDMA) time slot durations for both the parasitic SR (PSR) and commensal SR (CSR) cases. To solve the formulated non-convex optimization problems, we propose a Dinkelbach-based iterative algorithm that builds on the block coordinated decent (BCD) method and the successive convex programming (SCP) technique. Simulation results show that the proposed algorithm converges fast, and the system EE is maximized when the BD that can provide the highest EE is allocated the maximum allowed time for backscattering while guaranteeing the throughput requirements for both the primary link and the other backscatter links.

Light Energy Driven Nanocommunications With FRET in Photosynthetic Systems

Chlorophylls and carotenoids, key components of photosynthetic systems, are proposed for molecular communications at the nanoscale with the mechanism of resonance energy transfer. Both types of pigments are introduced focusing on their exceptional properties like energy harvesting, ultra-low energy consumption during transmissions, picoseconds delays, an ability for signal conversions, and bio-compatibility. The theoretical considerations are supported by two spectroscopic experiments on the photosystem II complex. The first experiment aims at the description of the photosystem II including calculation of the energy transfer efficiency between carotenoids and chlorophylls. In the second one, the photochemical efficiency is estimated, showing how effective the chlorophylls are in further energy processing. With the experimentally determined values, communication and energetic performance are analyzed, the probability of channel blockage is calculated and the energy consumption per bit is estimated. Treating carotenoid molecules as transmitters, chlorophylls as receivers, and the energy transfer between them as a way to encode information, a throughput up to 1 Gbit/s is achievable with a bit error rate below 10^-3, average transmission delays about 20 ps, and energy consumption c.a. 2.0x10^-18 J/bit. These results indicate a high potential of photosynthetic systems for nanocommunications and other related applications, due to suitable energetic characteristics in terms of energy harvesting abilities and low consumption for data transmissions.

Energy efficiency maximization strategy for Sink node in SWIPT-enabled sensor-cloud based on optimal stopping rules

Leveraging energy harvesting abilities in wireless network devices has emerged as an effective way to prolong the lifetime of energy constrained systems. The system gains are usually optimized by designing resource allocation algorithm appropriately. However, few works focus on the interaction that channel's time-vary characters make the energy transfer inefficiently. To address this, we propose a novel system operation sequence for sensor-cloud system where the Sinks provide SWIPT for sensor nodes opportunistically during downlink phase and collect the data transmitted from sensor nodes in uplink phase. Then, the energy-efficiency maximization problem of the Sinks is presented by considering the time costs and energy consumption of channel detection. It is proved that the formulated problem is an optimal stopping process with optimal stopping rules. An optimal energy-efficiency (OEE) algorithm is designed to obtain the optimal stopping rules for SWIPT. Finally, the simulations are performed based on the OEE algorithm compared with the other two strategies to verify the effectiveness and gains in improving the system efficiency.

Upwind Horizontal Axis Wind Turbine Output Power Optimization via Artificial Intelligent Control System

Power capturing capacity is one of the key performance indicators of wind turbines. This article presents a study done on the optimization of output power of upwind horizontal axis wind turbine using artificially intelligent control system. The study shows how blade tip speed ratio (λ) and pitch angle (β) are optimized to increase wind turbines power conversion coefficient (C_p) which increases the output power. An artificial intelligence system named Mandani fuzzy inference system (MFIS) was applied to optimize the power conversion coefficient in combination with blade pitch actuator control. To this end, a novel optimization technique is designed that maximizes the power harvesting ability of wind turbines by updating the parameters of the membership functions of fuzzy logic found in the MFIS. With the application of this optimization method, a power conversion coefficient C_p of 0.5608 value is achieved at optimal values of λ and β. As a result, the energy harvesting ability of the wind turbine considered is improved by 16.74%. This study clearly shows that the wind energy harvesting capacity of wind turbines can be enhanced via optimization techniques that could be further implemented in wind turbine blade pitch drive system. Thus, this novel optimization method creates further insights for the wind energy industry in reducing the cost of energy generation.