High-efficiency Energy Harvesting Research Articles

A Self-Powered Interface Circuit for Piezoelectric and Photovoltaic Energy Extracting

This paper presents a high-efficiency multi-source energy harvesting system consisting of a piezoelectric rectifier, a photovoltaic maximum power point tracking circuit and a fast self-startup circuit for powering wireless sensor nodes. Synchronous electric charge extraction techniques (SECE) are utilized to extract the piezoelectric energy when the deflection of piezoelectric energy harvester beam reaches its peak. Compared with other circuits, the proposed SECE technique can achieve piezoelectric and photovoltaic extraction simultaneously with a concise flyback topology structure. A novel maximum power point tracking method is adopted to enhance the robustness of operation against changing operating condition and improve the photovoltaic extraction efficiency. To remove the need for a battery, a simple and efficient self-startup circuit is introduced. The energy harvesting circuit is fabricated in 180 nm CMOS process. Measurement results show a fast self-startup at a relatively low light intensity of 120 lux is realized. The energy harvesting circuit is capable of outputting 189 μW power at 3.3 V piezoelectric open circuit voltage and 0.6 V photovoltaic input voltage.

Boosting FRET Efficiency of Chromophores with Aggregation-Caused Quenching by a Crystallization-Induced Precise Co-assembly Strategy.

Förster resonance energy transfer (FRET) plays a critical role in organic optoelectronic materials. However, developing facile and effective strategies to achieve high-efficiency energy harvesting of chromophores with aggregation-caused quenching (ACQ) remains an appealing yet challenging task, that has not yet been explored. Herein, a subtly strategy, crystallization-induced precise co-assembly (CIPCA) involving a molecular "lightening agent," to effectively improve FRET efficiency of ACQ chromophores is developed. Bis(phenylethynyl)anthracene (BPA) and bis(phenylethynyl)naphthacene (BPN) with significant ACQ effect are chosen as representative FRET donor and acceptor, respectively, and weakly-fluorescent octafluoronaphthalene (OFN) acted as the "lightening agent." Thanks to precise co-assembly with OFN, the PLQY of solid BPA is enhanced by 107%, and the BPN powder can be unprecedentedly lighted. More importantly, through such powerful CIPCA, the monotonous and weak emission for BPA@BPN can be remarkably regulated to colorful and much brighter ones with FRET efficiency improvement of as high as 180-270%. An in-depth understanding of FRET regulation is elucidated through a precise correlation of the supramolecular structures and properties. Such achievements allow to successfully fabricate distinct multi-stimuli-responsive fluorescent patterns and highly-emissive colorful flowers with high flexibility. This research provides an efficient strategy to improve the FRET efficiency of ACQ pairs.

High-efficiency quad-band RF energy harvesting system with improved cross-coupled differential-drive rectifier

Abstract RF energy harvesting technology has garnered significant attention from researchers in recent years. This paper presents a high-efficiency quad-band RF energy harvesting (RFEH) system. It introduces an improved cross-coupled differential-drive rectifier designed for ambient wireless powering, capable of harnessing power from four distinct ambient RF sources: FM-100, DTV-600, GSM-1800, and WiFi-2400 frequency bands. The proposed RFEH system demonstrates notable advancements, achieving a high RF to DC conversion efficiency of over 80 % within an input power range of −5 dB m to +13 dB m, with a 5 kΩ resistance load. This power output is deemed sufficient for energizing low-power micro-devices autonomously, without reliance on external power sources. Notably, the DC output voltage of the proposed RFEH system exhibits a high level of stability against variations in input power, a characteristic not adequately addressed in existing systems.

Construction of cellulose 3D network composite membrane supported by hydroxylated boron nitride with high surface charge density to achieve high-efficiency osmotic energy harvesting

Ion selectivity and mechanical persistence are critical properties of membranes to harvest osmotic energy. Two-dimensional nanofluidic membranes have been studied to enhance those properties, whereas they are usually constrained due to unsatisfactory mass transfer performances. Herein, a ternary three-dimensional membrane (T-CNF/PVDF/BN-OH composite membrane, abbreviated as CPBN) with distinct mechanical strength and high surface charge density (−2.65 mC·m−2) for sustainable osmotic energy harvesting is designed. In CPBN, negatively charged TEMPO-oxidized cellulose acts as a scaffold and constructs a 3D network structure together with the hydroxylated boron nitride (BN-OH) via a self-assembly process. The affluent nano-constrained ion channels effectively enhance the controllability and effectiveness of ion transport. The abundant ionized carboxyl groups extremely facilitate the selective transportation of the cations, while the BN-OH also assist this process, promoting the one-way transmission of cations in the channel. Additionally, the participation of PVDF polymer forms a network interlock structure, which significantly improves mechanical performances and stability in water. The membrane demonstrates a high power density (10.6 W/m2), measured in minimal testing areas, and an average power density around 1 W/m2 in larger areas, with an energy conversion efficiency of up to 30.7 %. This study provides a promising exploration of replacing traditional two-dimensional layered structure with three-dimensional network structure of cellulose for osmotic energy harvesting.

A High-Efficiency Piezoelectric Energy Harvesting and Management Circuit Based on Full-Bridge Rectification

This paper presents a high-efficiency piezoelectric energy harvesting and management circuit utilizing a full-bridge rectifier (FBR) designed for powering wireless sensor nodes. The circuit comprises a rectifier bridge, a fully CMOS-based reference source, and an energy management system. The rectifier bridge uses a PMOS cross-coupled structure to greatly reduce the conduction voltage drop. The CMOS reference source provides the necessary reference voltage and current. The energy management system delivers a stable 1.8 V to the load and controls its operation in intermittent bursts. Fabricated with a 110 nm CMOS process, the circuit occupies an area of 0.6 mm2, and is housed in a QFN32 package. Test results indicate that under 40 Hz frequency and 4 g acceleration vibrations, the chip’s energy extraction power reaches 234 μW, with the load operating every 3 s at a supply voltage of 1.8 V. Thus, this FBR interface circuit efficiently harnesses the energy output from the piezoelectric energy harvester.

Broadband and high-efficiency acoustic energy harvesting with loudspeaker enhanced by sonic black hole

It is well-known that acoustic energy sources can be seen as a promising alternative energy resource by using acoustic energy harvester (AEH) which can transform sound energy into usable electrical power. However, the current AEHs have been restricted by their narrow bandwidths and low energy conversion efficiencies. In this study, a broadband and high efficient AEH is presented. The proposed AEH comprises an open-end sonic black hole (SBH) structure and an electrodynamic loudspeaker. The sound pressure is amplified through the open-end SBH structure, then the loudspeaker is used as electricity generator to convert acoustic energy into electric energy. The open-end SBH is a cylindrical tube with an array of regularly-spaced rigid-walled thin rings. The inner radii of the SBH rings are quadratically decreasing and the SBH effect can be obtained. The model for energy harvesting and sound absorption performance of the proposed AEH is then presented. Finally, the open-end SBH is fabricated by 3D printing apparatus. A prototype of the AEH is designed and tested by using an impedance tube. The energy conversion efficiency and absorption coefficient from calculation and experiment show a reasonable agreement. The proposed AEH can convert 11 % of total incident sound energy from 50 Hz to 800 Hz. The maximum energy conversion efficiency can achieve 65 % at 425 Hz under optimal resistance load. Furthermore, the broadband sound absorption can also be achieved by using the proposed AEH.

The population growth model of electrostatic charges: A novel concept for engineering optimal performance triboelectric nanogenerators

Lateral sliding triboelectric nanogenerators LS-TENGs promise to combine low cost and high-efficiency mechanical energy harvesting at low frequency with the advantages of light weight and simple device architecture. To date, device power generation optimization has only been addressed on the framework of the optimal load resistance through the maximum power transfer theorem (MPTT). However, MPTT is a concept to optimize the power transferred from TENGs to loads, but not for optimizing the power generated by the TENG itself. In response, this work reports a concept that resembles the population growth model of species for designing enhanced performance LS-TENGs with optimal charge-generating rate. In this way, devices designed under the proposed concept possess a significantly enhanced optimal charge and power generation rate up to 3-fold and 8-fold respectively superior to those found for conventional rectangular TENGs with similar capacity, which allows us power up sustainably for hours low power consumption devices with a few minutes of mechanical energy harvesting. Thereby, this model aids in the development of enhanced performance LS-TENGs capable of collecting mechanical vibrations and optimally converting them into electrical energy by breaking the limits set by the MPTT, as well as opening a route towards batteryless power autonomy.

A bilayer angular selective surface with transmission at non-zero incident angle based on odd resonance of square ring slot FSS

In this paper, a bilayer angular selective surface (AGSS) is proposed and designed based on the first odd mode resonance of frequency selective surface (FSS). It can realize angular selective transmission (AST) at non-zero incident angles whereas reflection occurs at other angles. Based on the band pass FSS with square ring slot (SRS) structure, we cascade two uniform SRS structures with air space to form the quarter-wave stack. It can realize AST at 30° or 60° for TE or TM polarization, respectively. In addition, a bilayer FSS with maximum transmission at 30° under TE polarization is fabricated and measured. The measurement result shows good agreement with the simulation one, with -3 dB transmitted angular width of 10° The proposed angular selective surface can be applied in high efficient energy harvesting system and radar system with increased signal-to-noise ratio (SNR) level.

Nanoarchitectonics in Advanced Membranes for Enhanced Osmotic Energy Harvesting.

Osmotic energy, often referred to as "blue energy", is the energy generated from the mixing of solutions with different salt concentrations, offering a vast, renewable, and environmentally friendly energy resource. The efficacy of osmotic power production considerably relies on the performance of the transmembrane process, which depends on ionic conductivity and the capability to differentiate between positive and negative ions. Recent advancements have led to the development of membrane materials featuring precisely tailored ion transport nanochannels, enabling high-efficiency osmotic energy harvesting. In this review, ion diffusion in confined nanochannels and the rational design and optimization of membrane architecture are explored. Furthermore, structural optimization of the membrane to mitigate transport resistance and the concentration polarization effect for enhancing osmotic energy harvesting is highlighted. Finally, an outlook on the challenges that lie ahead is provided, and the potential applications of osmotic energy conversion are outlined. This review offers a comprehensive viewpoint on the evolving prospects of osmotic energy conversion.

Exploring ferroelectric and photovoltaic attributes of Pna21-LaWN3: A first-principles approach

Traditional ferroelectric perovskite oxides are often limited by their wide band gaps, which restrict their efficient use of visible light. Pna21-LaWN3, an innovative perovskite nitride featuring a polar structure, has been investigated for its electronic structure, ferroelectric properties, and photovoltaic performance through Density Functional Theory (DFT) analysis. Our calculations reveal that Pna21-LaWN3 exhibits promising ferroelectric properties, primarily driven by the interaction between W and N atoms. Notably, Pna21-LaWN3 possesses a direct bandgap around 1.3 eV, coupled with a high absorption coefficient, making it highly efficient in absorbing visible light. SLME (Spectroscopic Limited Maximum Efficiency) analysis indicates that Pna21-LaWN3 can achieve significant short-circuit current, with a photoelectric conversion efficiency nearing 32 %, thus emerging as an outstanding candidate for ferroelectric photovoltaic applications. The study underscores the potential of Pna21-LaWN3 in overcoming the limitations of traditional ferroelectric materials and paves the way for its use in high-efficiency solar energy harvesting.

Rainbow energy harvesting using a high-order topological meta-device

We present an innovative rainbow piezoelectric energy harvesting approach that harnesses the untapped potential of the topological meta-device for robust and efficient vibration energy trapping and conversion, from its theoretical rudiments, through design of the device to experimental validation. The rigorously designed meta-device features a series of second-order phononic topological insulators to host topologically protected corner states of different eigenfrequencies. By tailoring and tuning various corner sites, multi-frequency vibrations along a specially engineered channel that supports the edge states spanning these frequencies can be trapped into different corner sites. The vibrational energy is thus converted into electrical energy efficiently using strategically placed piezoelectric harvesters. Experimental results reveal the capability of the device in trapping targeted vibration, in which vibrational energy can be trapped into different corner sites in terms of its frequency, leading to an interesting rainbow energy conversion. This new approach not only implements high-efficiency energy harvesting but also offers enhanced design flexibilities for diverse applications by spatially separating vibrational frequencies.

A study on novel dual-functional photothermal material for high-efficient solar energy harvesting and storage

The solar-heat storage efficiency of devices based on phase change materials (PCMs) is limited due to the light absorption and internal heat transfer within the PCMs, unclear thermal conductivity-enhancement mechanism within nanocomposite PCMs, and uncontrollable photothermal-interface modulation. Therefore, a novel controllable strategy was proposed in this study to fabricate dual-functional photothermal storage three-dimensional (3D) phase change blocks (PCBs) with higher thermal conductivity (27.98 W/m·K) and spectral absorption (98.03 %) compared to those of most previously reported PCM-based devices. The as-synthesized PCBs contained millimeter-sized graphite plates with horizontal Van der Waals bonds and oriented micro/nanoscale graphite nanosheets. The structural properties of thin PCM layers between the PCB sheets have synergistically reduced the internal interfacial thermal resistance of the PCBs. Laser-controllable induction was used to fabricate integrated biomimetic-forest 3D optical absorbers on the high thermal conductivity interface of the PCBs, which significantly reduced the thermal resistance of the optical-thermal interface. The resulting 3D-PCBs, integrated with thermoelectric generators, powered portable electronic devices, expanding the applications of traditional PCM heat-storage devices. Therefore, this study will guide the future design of high-performance solar-thermal storage PCMs with a wide range of practical applications.

Harnessing energy from hand-shaking vibration for electronics through a magnetic rolling pendulum bistable energy harvester

Converting the kinetic energy of human movement into electricity provides a solution for the power supply of portable electronics for communication, medical treatment, positioning, search-and-rescue, etc. Due to the characteristics of high sensitivity and snap-through, a magnetic rolling pendulum bistable energy harvester (MRP-BEH) based on magnetic-spring mechanism is proposed for scavenging energy from handshaking vibration. The harvester possessing the advantage of small damping exploits the rolling oscillation of a suspended magnet. By establishing the electromechanical model, numerical outcomes of the MRP-BEHs with different potential well depths are investigated through the response under constant and sweep frequency excitations. Particularly, the complex dynamic behaviors are characterized by basins of attraction and bifurcation diagrams. A prototype is fabricated, and experiments are undertaken under harmonic and handshaking excitations. Experimental results are consistent with numerical simulations, and excitation of 0.5 g witnesses a broadband frequency range from 5.18 Hz to 10.02 Hz for the harvester with proper system parameters. Regarding the excitation of handshaking, an instantaneous maximum power of 21.9 mW and an average power of 4.21 mW is achieved with matched load resistance. By boosting the output voltage with a transformer, the charging and discharging experiments of capacitors for powering various electronics demonstrate the broad application prospects of the harvester. This research, in a nutshell, broadens the methodology for achieving bistable oscillation and introduces a fresh perspective for designing high-efficiency energy harvesters attuned to human motion.

Design and optimization of quasi-zero-stiffness dual harvester-absorber system

The single quasi-zero-stiffness harvester-absorber system has shown its effectiveness in harvesting vibration energy and suppressing low-frequency vibrations simultaneously. Nevertheless, drawbacks of narrow frequency range of vibration suppression and low output power are still challenges. In this paper, a novel quasi-zero-stiffness dual harvester-absorber system (QZS DHAS) is proposed for broadband synergistic vibration suppression and energy harvesting at low frequency. The QZS feature is realized by mounting an equal-strength piezoelectric beam and a pair of magnet rings in parallel. Firstly, the restoring force of both the piezoelectric beam and the magnet rings are theoretically derived, respectively, which are verified by finite element simulations. Then, the governing equations of a host oscillator with QZS DHAS are derived based on Newton's law and Kirchhoff's law, which are solved by the harmonic balanced method combined with the pseudo arc-length continuation method. Moreover, the effects of mass ratios, frequency ratios and damping ratios on the performance of the QZS DHAS are investigated in details. Finally, the parameters of the QZS DHAS are optimized to improve the performance of vibration suppression and energy harvesting by using the multi-objectives genetic algorithm in combination with the technique of establishing order preference by similarity to the ideal solution. The results show that the peak response of the host oscillator is reduced by 33.48 % and the peak power is increased by 531.38 % after optimization, which indicates that the dual objectives of broadband vibration absorption and high-efficiency energy harvesting are fulfilled.

A flame-retardant, hydrophobic and thermo-responsive multi-functional fabric: Application in fire-alarm device and self-powered system

Conventional textiles present high flammability and rapid-fire propagation, posing significant fire hazards in daily life. In this study, nylon and cotton fabrics were endowed with flame retardancy and hydrophobicity, and a low-cost and eco-friendly flame-retardant and hydrophobic fabric-based triboelectric nanogenerator (FHF-TENG) was fabricated through integrated and modular design. This TENG exhibits excellent flame-retardant properties (self-extinguishment and melt-dripping resistance) and high energy harvesting efficiency (with a maximum output power of 173 mW/m2). Furthermore, the FHF-TENG was successfully employed in a fire-alarm system as a self-powered sensor, providing fire-warning signals for evacuees and fire rescue operations. This work advances the development of fire rescue field and showcases innovative application of multifunctional smart textiles in energy harvesting and self-powered sensing.

Magnetic-linkage nonlinear piezoelectric energy harvester with time-varying potential wells: Theoretical and experimental investigations

Energy harvesting has emerged as a prospective solution for powering wireless sensors on the Internet of Things (IoT). However, the limited energy conversion efficiency remains a significant challenge, thereby hindering the feasibility of self-powered sensing in IoT. To address this issue, this paper proposes a magnetic-linkage nonlinear piezoelectric energy harvester (PEH) capable of effectively operating over a wide frequency bandwidth, particularly under low-level base excitations. The proposed PEH comprises one vertical and two horizontal piezoelectric beams, which are coupled by the magnetic force to realize the magnetic-linkage effect and create time-varying potential wells. A comprehensive theoretical model has been developed to reveal the working mechanisms of the magnetic-linkage effect and corresponding time-varying potential wells. Based on these foundations, theoretical results indicate that the magnetic configuration parameters have a significant impact on the magnetic-linkage effect and potential barriers. In addition, experimental investigations indicate that the magnetic-linkage effect broadens the effective frequency bandwidth, leading to a significant improvement in energy harvesting efficiency of up to 400% compared to the PEH without magnetic-linkage effect. Furthermore, the proposed PEH enables the realization of self-powered sensing in experiments. In summary, by exploiting the magnetic-linkage effect to create the time-varying potential wells, this innovative approach holds a great promising application for achieving high-efficiency energy harvesting from low-level environmental vibrations.

Perforated auxetic honeycomb booster with reentrant chirality: A new design for high-efficiency piezoelectric energy harvesting

The present study develops an auxetic meta-structure booster to advance piezoelectric energy harvesting (PEH). The model comprised a three-dimensional (3D) cantilever beam equipped with an auxetic substrate bonded to a piezoelectric (PZT) point defect using an epoxy layer. The substrate used in this proposed energy harvester possesses an auxetic region responsible for generating auxetic behavior and concentrating stress in the PZT layer. The auxetic model called auxetic structure (AS)-II is inspired by ancient motifs and is designed based on the combination of several promising mechanisms, including reentrant, chiral, perforation, and honeycomb supercell. The finite element method is employed to create numerical models whose accuracy is confirmed by mesh convergence and available experimental data. A parametric study is conducted on the AS-II harvester to examine the influence of geometry and PZT material type on the harvested electrical power. Our research efforts stem from both mechanical and electrical circuit fields to fulfill the broadband design target within the desired ultra-low-frequency range of regardless of the resonance condition. As a result, the impact of other factors, such as load resistance, frequency, load amplitude, and bonding stiffness, on the PEH performance is further investigated. The reason behind such outstanding performance of AS-II is explained in terms of geometrical physics and stress distribution. The effect of geometrical dimensions on the auxetic behavior is also analyzed using Poisson’s ratio (PR) study. Subsequently, we demonstrate that this innovative adapter can advance the system’s performance in terms of harvested power and lightweight by a magnification factor of and times that of a plain substrate and and 3.16 times that of a conventional auxetic harvester, respectively. The present harvester is strain controllable, where it can set PR between and resulting in robust PEH even if switching input vibration from high to low levels. This new idea enables us to serve cantilever-type resonators at frequencies far lower than their resonant frequencies with small portions of incident excitement.

High-efficiency magnetic field energy harvesting from a three-core cable

Alternating magnetic fields generated by ac power lines are renewable energy sources that can be scavenged by magnetic energy harvesting cores for wireless sensor networks (WSNs). However, traditional magnetic cores are suffering from low efficiency when applied to three-core cables. This paper systematically analyzed the characteristics of the magnetic induction intensity of a three-core cable by finite element methods (FEM), figured out the optimal energy harvesting position, innovatively designed and fabricated a novel notched ring core (NNRC) to better match the magnetic field characteristics of three-core cables. Compared with the previously reported core, the NNRC has 2.3 times the output voltage per turn and more space allowance for winding coil. According to experimental results, the open-circuit output voltage amplitude of NNRC was 16.6 V with 9000 turns of wire and 100 AAMP ac current in each phase of the cable. Finally, a non-controlled AC/DC circuit was applied and 28.4 mW maximum dc power was obtained.

Constructing quasi-layered and self-hole doped SnSe oriented films to achieve excellent thermoelectric power factor and output power density

Thermoelectric (TE) technology can achieve the mutual conversion between electric energy and waste heat, and it has exhibited great prospects in multifunctional energy applications to alleviate the energy crisis. In the recent decade, SnSe has been explored widely because of its potentially high energy harvesting efficiency, green nature, and low cost. However, the relatively poor power factor (PF) derived from the intrinsic low carrier concentration (∼1017 cm−3) limits the output power density of the stoichiometric SnSe devices. Therefore, the advancement of novel optimization strategies for controlling carrier concentration is of utmost importance. Besides, compared with 3D bulks, 2D thin films are more compatible with modern semiconductor technology and have unique advantages in the construction and application of TE micro- and nano-devices. In this study, post-selenization technology were applied to increase the carrier concentration of the a-axis oriented SnSe epitaxial films utilizing the charge transfer and self-hole doped effects. The quasi-layered and self-hole doped films exhibited a high power factor of ∼5.9 µW cm−1 K−2 at 600 K along the in-plane direction when the carrier concentration is enhanced to ∼1018 cm−3 by increasing the selenization time to ∼20 min. The TE generator composed of four P-type film legs demonstrated the ultrahigh maximum power density of ∼83, ∼838 µW cm−2 at the temperature difference of ∼50 and ∼90 K, respectively. Post-selenization can effectively optimize the carrier concentration of SnSe-based materials, which is also feasible to other anion deficient TE films.

From Triboelectric Nanogenerator to Hybrid Energy Harvesters: A Review on the Integration Strategy toward High Efficiency and Multifunctionality.

The rapid development of smart devices and electronic products puts forward higher requirements for power supply components. As a promising solution, hybrid energy harvesters that are based on a triboelectric nanogenerator (HEHTNG) show advantages of both high energy harvesting efficiency and multifunctionality. Aiming to systematically elaborate the latest research progress of a HEHTNG, this review starts by introducing its working principle with a focus on the combination of triboelectric nanogenerators with various other energy harvesters, such as piezoelectric nanogenerators, thermoelectric/pyroelectric nanogenerators, solar cells, and electromagnetic nanogenerators. While the performance improvement and integration strategies of HEHTNG toward environmental energy harvesting are emphasized, the latest applications of HEHTNGs as multifunctional sensors in human health detection are also illustrated. Finally, we discuss the main challenges and prospects of HEHTNGs, hoping that this work can provide a clear direction for the future development of intelligent energy harvesting systems for the Internet of Things.