Multimodal Energy Harvester Research Articles

Flexible carbon-coated paper electrokinetic generator with Schottky-junction

Simulating transpiration effect to harvest electricity has attracted continued interest. However, it is limited to directional water/ions transport that shrinks the application scenario. Herein, we propose a new carbon-coated paper electrokinetic generator with Schottky-junction to induce the electricity. The electrical double layer (EDL) forms at carbon-water interface due to the wetting paper that induces an obvious electrical sign. The introduce of Schottky-junction inhibits the carrier recombination that enhances the charge separation. As a result, the output performance is significantly improved. Besides, it breakthroughs the limitation of directional water/ions transport to realize multi-mode energy harvesting due to joint working mechanisms of EDL and Schottky-junction. Consequently, the electrical sign is still remained in the case of full wetting rather than disappearance, showing great potential in practical applications. As a demonstration, it can judge the condition of simulated pipe through the feedback of electrical signal, charges the capacitors to energy storage and powers digital calculator, et al. The cheap and flexible paper-based generators offer a new path to clean energy harvesting and sensor applications.

A multi-directional and multi-modal galloping piezoelectric energy harvester with tri-section beam

A traditional wind energy harvester based on galloping can only harvest wind energy from one specific direction, which fails to work efficiently in a natural erratic environment. In this study, we propose a galloping-based piezoelectric energy harvester that can collect energy from wind flow in a wide range of incident directions with multiple vibrational modes being excited. The proposed harvester is composed of a tri-section beam with bonded piezoelectric transducers and a square bluff body with splitters. Finite element analysis of the tri-section beam structure is first performed and confirms the clustered natural frequencies that ease the excitation of different modes. Then, the aerodynamic characteristics of various bluff bodies is conducted through computational fluid dynamics to compare the capability of galloping. Finally, the wind tunnel experiment is carried out to test the wind energy harvesting performance by utilizing the harvester’s multi-modal characteristics. The results of this study demonstrate that the proposed harvester can harvest wind energy in multiple directions with the capability of galloping in multiple vibrational modes, and superior performance is achieved when the second bending mode is triggered. The novel design of the harvester from this work provides a viable solution for harvesting wind energy in a natural environment with varying wind conditions.

A mechanically robust spiral fiber with ionic-electronic coupling for multimodal energy harvesting.

Wearable electronics are some of the most promising technologies with the potential to transform many aspects of human life such as smart healthcare and intelligent communication. The design of self-powered fabrics with the ability to efficiently harvest energy from the ambient environment would not only be beneficial for their integration with textiles, but would also reduce the environmental impact of wearable technologies by eliminating their need for disposable batteries. Herein, inspired by classical Archimedean spirals, we report a metastructured fiber fabricated by scrolling followed by cold drawing of a bilayer thin film of an MXene and a solid polymer electrolyte. The obtained composite fibers with a typical spiral metastructure (SMFs) exhibit high efficiency for dispersing external stress, resulting in simultaneously high specific mechanical strength and toughness. Furthermore, the alternating layers of the MXene and polymer electrolyte form a unique, tandem ionic-electronic coupling device, enabling SMFs to generate electricity from diverse environmental parameters, such as mechanical vibrations, moisture gradients, and temperature differences. This work presents a design rule for assembling planar architectures into robust fibrous metastructures, and introduces the concept of ionic-electronic coupling fibers for efficient multimodal energy harvesting, which have great potential in the field of self-powered wearable electronics.

A multi-frequency and multi-mode metasurface energy harvester for RF energy harvesting

Metasurface energy harvesters (MEHs) lessen the dependence of wireless communication devices on batteries or other external power sources by capturing untapped electromagnetic energy in the surroundings. In this paper, we propose a multi-frequency and multi-mode microwave metasurface for efficient radio frequency (RF) and microwave energy harvesting. The MEH is comprised of a sub-wavelength resonant ring array, which can harvest RF energy in both Wi-Fi and 5 GHz bands. A feeding network is designed to integrate the TE and TM wave energy collected by the MEH into two separate networks that each gather AC energy and deliver them to the resistive loads. In terms of the simulation’s results, the efficiency of energy harvesting at frequencies of 2.4 GHz, 3.1 GHz, as well as 3.6 GHz is 91.3%, 88.9%, and 73.9%, specifically. We manufactured a 6 × 6 array sample and conducted experiments utilizing a microwave anechoic chamber. The simulation results and results from experiments were approximately identical. The proposed design has potential applications in various fields, such as efficient wireless energy harvesting systems, self-powered devices, which has a significant potential on the environment and the energy sector by reducing carbon emissions and reducing reliance on non-renewable energy sources.

Multimodal piezoelectric energy harvesting on a thin plate integrated with SSHI circuit: an analytical and experimental study

Multimodal piezoelectric energy harvesting can be achieved by integrating piezo-patch harvesters into plate-like structures available in marine, aerospace, and automotive applications. A synchronized switch harvesting on inductor (SSHI) interface as the harvesting circuit has been well studied for cantilever beams, considering the single vibration mode of the structure. However, integrating a two-dimensional electromechanical structure with a SSHI circuit for multimodal energy harvesting is missing in the literature. This paper evaluates the performance of the SSHI interface integrated with a piezoelectric energy harvester (PEH) on a plate-like host structure. The analytical solution is developed based on an equivalent impedance approach to predict the steady-state electrical response of the harvester as a closed-form solution. The experiments are conducted to validate the analytical solution for the system’s first and second vibration modes. The experimental results reveal that integration of SSHI to a plate-like harvester introduces a multi-switching behavior rather than a standard single-switching behavior. Due to the multimodal vibrational characteristics of the plate, the circuit switch is triggered several times at each half period of the vibration, which increases the energy dissipation of the circuit and thus reduces the output voltage. On the other hand, single switching at each half period of the vibration happens for lower piezoelectric voltage levels. This is the desired behavior of the SSHI circuit where the analytical prediction matches with the experimental data. Finally, the energy harvesting performance of the SSHI circuit is compared against the standard rectifier, showing 183% and 134% power output enhancement for the first and second vibration modes, respectively.

Multimodal energy harvesting and catalysis of piezoelectric nanosheets for efficient and round-the-clock wastewater treatment

Solar-driven pollutants degradation is an important way for green wastewater treatment, but it is still limited by the intermittent solar flux. Here, we have prepared piezoelectric Bi4Ti3O12 (BTO) nanosheets with abundant physical properties, which can convert extensive solar energy, mechanical energy and temperature variation energy into electrical and chemical energy. It can be used for round-the-clock wastewater treatment by harvesting multi-modal energy. More importantly, the degradation rate of piezoelectric nanosheets can reach 153.4 × 10-3 min−1, and nanosheets can degrade many organic pollutants. In addition, we fabricate porous foam catalysts based on BTO-polydimethylsiloxane (PDMS) composite to prevent secondary contamination. Our results suggest that BTO nanosheets with photoelectric, piezoelectric and pyroelectric catalysis offer a potential approach for round-the-clock wastewater degradation by harvesting solar energy, ambient mechanical energy, and cyclic thermal energy.

A 3D multi-directional and multimodal broadband vibration energy harvester using an L-shaped bending beam

A three-dimensional (3D), multi-directional and multimodal broadband vibration energy harvester using L-shaped curved beams is proposed in this paper. The harvester is composed of an L-shaped cylindrical bending beam and a piezoelectric beam. The free ends of the L-shaped bending beam and the piezoelectric beam are respectively fixed with a magnet. These two beams are coupled by nonlinear magnetic force introduced by the two magnets. The results show that the prototype can collect 3D multi-directional broadband vibration energies and has three natural frequencies in 3D directions. Under 5 m/s2 acceleration, the prototype obtains 42.1V, 45.0V and 66.9V peak-peak voltages in the x-direction, y-direction and z-direction respectively, and the widest 3 DB bandwidths in this three directions reach up to 6.4Hz, 6.3Hz and 4.2Hz, respectively.

A novel multimodal piezoelectric energy harvester with rotating-DOF for low-frequency vibration

This paper proposes a novel piezoelectric energy harvester with rotating-DOF to efficiently achieve multimodal vibration energy harvesting in low-frequency environments. The designing of the harvester based on the beam whose ends were connected to rotating shafts was accomplished firstly, and then the dynamic properties of the structure were numerically calculated by finite element analysis. Finally, experimental prototypes and test systems were designed to verify the correctness of the theory. This paper analyzed how that different key structural parameters and acceleration affect its output characteristics. Especially, the effect of double-rotating shafts on the energy harvesting performance was analyzed innovatively. The results acquired by experiments were in accord with those of simulation. Its first-order resonant frequency is down to 12.65 Hz, at which excellent output characteristics were obtained. The harvesting performance at the third-order resonant frequency was also remarkable, indicating the application prospect in the multimodal vibration circumstances. Moreover, the harvesting performance can be enhanced by the adjustable counterweight and proof mass, which improve environmental adaptability. Its maximum output is 35.73 V (12.65 Hz) and 24.69 V (43.64 Hz), and the output power is 2.13 mW and 1.02 mW under an acceleration of 1.96 m/s2. This paper provides a novel idea for low-frequency multimodal energy harvesting techniques.

Design, modeling, and experimental verification of reversed exponentially tapered multimodal piezoelectric energy harvester from harmonic vibrations for autonomous sensor systems

Design, modeling, and experimental verification of reversed exponentially tapered multimodal piezoelectric energy harvester from harmonic vibrations for autonomous sensor systems

Multimodal MEMS vibration energy harvester with cascaded flexible and silicon beams for ultralow frequency response

Scavenged energy from ambient vibrations has become a promising energy supply for autonomous microsystems. However, restricted by device size, most MEMS vibration energy harvesters have much higher resonant frequencies than environmental vibrations, which reduces scavenged power and limits practical applicability. Herein, we propose a MEMS multimodal vibration energy harvester with specifically cascaded flexible PDMS and “zigzag” silicon beams to simultaneously lower the resonant frequency to the ultralow-frequency level and broaden the bandwidth. A two-stage architecture is designed, in which the primary subsystem consists of suspended PDMS beams characterized by a low Young’s modulus, and the secondary system consists of zigzag silicon beams. We also propose a PDMS lift-off process to fabricate the suspended flexible beams and the compatible microfabrication method shows high yield and good repeatability. The fabricated MEMS energy harvester can operate at ultralow resonant frequencies of 3 and 23 Hz, with an NPD index of 1.73 μW/cm3/g2 @ 3 Hz. The factors underlying output power degradation in the low-frequency range and potential enhancement strategies are discussed. This work offers new insights into achieving MEMS-scale energy harvesting with ultralow frequency response.

A multimodal E-shaped piezoelectric energy harvester with a built-in bistability and internal resonance

The abundant and renewable vibration energy has been regarded as an alternative power source for the massive sensors of the Internet of Things, but the broadband and efficient vibration energy harvesting is still an open issue. In this paper, a broadband E-shaped bistable piezoelectric energy harvester (EBPEH) is developed by taking advantages of nonlinear and multimodal techniques. It is consisted of a steel U-shaped host beam (UHB) and a steel parasitic piezoelectric cantilever beam (PPCB). The nonlinear interaction between a tip magnet of the PPCB with the UHB cause a built-in bistability of the harvester, eliminating the need of any external magnet and leading to a compact structure. By appropriately designing multimodal frequencies of two beams, a 1:2 internal resonance phenomenon in the first response frequency band occurs, and an overlapping of them above a low excitation amplitude threshold cause a triple bandwidth enhancement from 6 Hz to 18.5 Hz. Attributed to the nonlinear hardening phenomenon, the peak voltage and the RMS peak power can reach 56.1 V and 786.8 μW under the 0.5 g up sweep excitation, respectively. It is proved that the proposed EBPEH has the ability to harvest wideband and low frequency vibration energy.

ZnFe2O4 nanocomposite films for electromagnetic-triboelectric-piezoelectric effect-based hybrid multimodal nanogenerator

Hybridizing the pre-existing energy harvesting techniques in a single device is in focus nowadays to improve the electrical output of energy harvesting device. This work uses a versatile nanocomposite films comprises cuboctahedron zinc ferrite nanoparticles (CZF NPs) and polymer matrix as energy harvesting layers to implement a hybrid multimodal nanogenerator (HNG) of a triboelectric nanogenerator (TENG), a piezoelectric nanogenerator (PENG), and an electromagnetic nanogenerator (EMG). Polydimethylsiloxane (PDMS) and polyvinylidene fluoride (PVDF) were used as polymer matrix materials of two different nanocomposite films. With embedded multi-spiral coil structuring, CZF NPs @PDMS composite film works for the EMG and the TENG. Furthermore, ferroelectric CZF NPs @PVDF composite film produces piezoelectric output by pushing force, serving as the PENG. Our HNG provides an efficient multimodal energy harvesting as the integrated nanogenerators generate high output power with not only high output voltage, but also low internal electrical impedance with three different working modes including non-contact mode, contact-separation mode, and non-separation mode in response to the external mechanical pushing force and its release. We believe that these techniques can realize the commercial application of flexible hybrid nanogenerators.

A Proof-of-Concept Study on an Internal-Resonance-Based Piezoelectric Energy Harvester With Coupled Three-Dimensional Bending-Torsion Motions

Abstract By exchanging the internal energy between coupled vibration modes, internal-resonance-based energy harvesters may provide an effective solution to broadening and enhancing bandwidth and power performance in dealing with natural vibration sources. With the development of piezoelectric-based transducers, thickness and face shear coefficients in proper piezoelectric elements can also generate power output from shear deformation on the core vibrating elements. However, in most cantilever-based energy harvesters that focused on bending modes, the shear responses were neglected. In this paper, we present an internal-resonance-based piezoelectric energy harvester with three-dimensional coupled bending and torsional modes, for the first time. The fine-tuned system leverages a two-to-one internal resonance between its first torsion and second bending modes to enhance the power output with piezoelectric effects. The dynamic behavior implies the coexistence of in-plane and out-of-plane motions under a single excitation frequency, and the corresponding strain changes in the bending and shear directions are captured by bonded piezoelectric transducers. Dependence between excitation levels and the internal-resonance phenomenon is justified as a critical system parameter study; the results also indicate that an intriguing non-periodic region exists near the center frequency. The outcomes of this study feature a multi-directional and multi-modal energy harvester that displays rich dynamic behaviors. The operational bandwidth is promising for broadband energy harvesting, and the output voltage is enhanced by capturing both in-plane and out-of-plane motions at the same time.

High-Performance Piezoelectric Nanogenerator Based on Low-Entropy Structured Nanofibers for a Multi-Mode Energy Harvesting and Self-Powered Ultraviolet Photodetector

High-Performance Piezoelectric Nanogenerator Based on Low-Entropy Structured Nanofibers for a Multi-Mode Energy Harvesting and Self-Powered Ultraviolet Photodetector

A novel soft encapsulated multi-directional and multi-modal piezoelectric vibration energy harvester

Advances in the design of various piezoelectric vibration-based energy harvesters (PVEHs), as a kind of power devices that can convert ambient energy to useable electrical energy, have become a hot topic in recent years due to their potential perspectives in wireless sensor networks, wearable electronics and low-power microelectronics. Unfortunately, conventional PVEHs modelled by beam- or plate-type planar structures are mainly restricted to harness kinetic energy in a single direction only. However, ambient vibration sources often work in multiple directions and broadband frequencies. To address this challenging problem, a mechanically-guided three-dimensional (3D) assembly structure is strategically designed to construct a soft cruciform-encapsulated PVEH in this work. Meanwhile, a reliable soft encapsulation technology is introduced to maintain the 3D configuration, which not only can avoid the collapse problem and also improve the dynamical performance. The entire system consists of a compressive buckling cruciform structure with a proof mass, PVDF thin film, and soft encapsulation. The dynamic characteristics of the system can be adjusted by changing the structural parameters, such as the pre-stressing force of the pre-stretched elastic substrate and the quality of the additional mass block. Finite element analysis and experimental studies are conducted to investigate the modal characteristics of system. A comparison of the vibration energy harvesting performance between the encapsulated and unencapsulated piezoelectric harvesters is presented. The results demonstrate that the encapsulated one can work well under multi-directional, multi-modal and low-frequency conditions. A maximum power output of 9.8 mW in the frequency range of 1–200 Hz can be achieved, which is almost 560 times more than that of the unencapsulated one. The proposed methodology also offers a new perspective for the fabrication design of soft-type PVEHs with higher working performance.

Nonlinear multimodal energy harvesting system: A dual-cantilever beam structure for combining piezoelectric and electromagnetic mechanisms

A nonlinear piezoelectric-electromagnetic composite energy harvester (NEPH) is proposed. The dynamic equations of its electromechanical system are established and numerical methods are used to simulate its voltage output characteristics if the system parameters are changed. The experimental setup is built up to measure the output characteristics of the prototype. Experimental results show at the first resonant frequency (22 Hz), the total power of the PH generator under a load impedance of 50 kΩ is 5.51 mW, and the total power of the EH generator under a load impedance of 200 Ω is 72.48 μW; at the second resonant frequency (30 Hz), the total power of the PH generator under load impedance of 50 kΩ is 1.79 mW, and the total power of the EH generator under load impedance of 200 Ω is 27.42 μW. In addition, the two electromagnetic generators have the same amplitude, frequency, and phase, so they can be directly connected in series or parallel without rectification. Finally, a practical application in driving electronic loads proves the potential value in supplying power to some low-power electronic devices.

A Multi-Modal Energy Harvesting Device for Multi-Directional and Low-Frequency Wave Energy

As a kind of sustainable energy source, ocean wave energy has always attracted attention. Because of the characteristics of multi-directions and low-bandwidth, the harvesting of wave energy has always been difficult. To harvest broadband wave energy in multiple directions and improve power generation efficiency, we present a multi-modal energy harvesting device by using a cross beam structure. In this device, the efficient harvesting of multi-frequency vibration energy in multiple directions has been achieved by using the multi-modal characteristics of the structure and the high power generation efficiency of the electric device based on liquid metal. Contrast experiments in multiple directions show that the device not only has the capability of multi-directional energy harvesting but also can work in the sweep range of the full band. Under horizontal excitation, compared with traditional single cantilever structure, the peak power density increased to 2227% and the working frequency band increased to 6.25 times. The experimental results show that the device significantly improves the efficiency of low-bandwidth multi-directional energy harvesting, providing a new method for vibration energy harvesting.

Design and Optimization of a Multimode Low-Frequency Piezoelectric Energy Harvester

In this paper, we present a microelectromechanical systems (MEMS)-based multimode low-frequency piezoelectric energy harvester (PEH), which can operate at low resonant frequencies (i.e., [Formula: see text][Formula: see text]Hz). The proposed harvester has a symmetric serpentine structure with a doubly clamped configuration comprising several proof masses at the junctions. The optimal parameters of the proposed energy harvester are determined by a computerized optimization technique based on a genetic algorithm (GA). Finite element simulations showed that the optimization results can generate high voltage with two usable low-frequency resonant frequencies. Furthermore, we discuss the array structure based on the proposed PEH. Finite element simulations demonstrate that our piezoelectric MEMS harvester array can generate voltage with a frequency ranging from 110.95 to 157.84[Formula: see text]Hz. Its normalized power density (NDP) when operating in the first four modes is 1284, 932, 1978, and 2592 [Formula: see text]Wcm−3 m−2s4, respectively, and its performance outperforms those of previously reported MEMS-based energy harvesters.

Bi-Directional Piezoelectric Multi-Modal Energy Harvester Based on Saw-Tooth Cantilever Array.

The paper presents numerical and experimental investigations on a bi-directional multi-modal energy harvester which is based on a piezoelectric saw-tooth cantilever array. The harvester is composed of four piezoelectric cantilevers which are connected rigidly to each other. At each junction of the cantilevers, there are placed seismic masses which are used to reduce resonant frequencies of the cantilever array. Moreover, at the center of the cantilever array is placed a Z-shaped seismic mass, which is used to obtain an additional rotation moment during excitation of the energy harvester to this way increase the stability of output characteristics via the whole angular range. The rigid connection between cantilevers ensures the transfer of bending deformations from cantilevers which are resonant to cantilevers which are out of resonance operation mode. The design of cantilever array ensures that all piezo ceramics are affected or partly affected by bending deformations while excitation frequency changes from 10 Hz to 160 Hz. In addition, such a composition of the array ensures the multi-modal operation principle. Additionally, the proposed cantilever array is designed to respond to changes of excitation force angle in an XY plane. The numerical and experimental investigation have shown that the proposed energy harvester has four resonant frequencies at a range from 10 Hz to 160 Hz. The electrical characteristics of the harvester were investigated as well. The results of these investigations have shown that cantilever array is able to provide an average output power of 15.3 mW while excitation amplitude is 0.5 m/s2 and the angle of excitation force changes in range from 0° to 350°.

A hybrid multimodal energy harvester for self-powered wireless sensors in the railway

The operational safety and reliability of the railway in monitoring systems are constantly increasing. However, the self-powered functioning of sensors utilizing energy harvesting technologies could be a challenge due to wireless sensors in the railway. This paper presents a hybrid multimodal renewable energy harvesting system (HHMRES) to power the wireless monitoring sensors such as accelerometer, humidity sensor, inclinometer, and light sensor alongside the railway in remote areas. The system design consists of a multimodal renewable energy system, power generation, and energy storage system. A hybrid solar photovoltaic system combined with a 3D printed wind turbine coupled with an electromagnetic generator was proposed as HHMRES to harvest solar and wind energy simultaneously. The harvested energy can be stored in super-capacitors and utilized for wireless monitoring sensors alongside the railway. A theoretical model has been developed to characterize the HHMRES. The total pressure and velocity contours were studied through the simulations in ANSYS FLUENT. The experiments were carried out to validate the performance and dynamics of the HHMRES by simulating solar radiations and wind flow with a solar simulator and the wind tunnel, respectively. The results showed that the average output power of the proposed system was 12.31 W at 17.5 m/s wind speed and 1700 W/m2 solar radiations. The techno-economic optimization of HHMRES was performed in HOMER software to find the most optimal design structure, capital cost, operating cost, and replacement cost of the proposed model. The harvester was demonstrated to have significant power output to operate wireless sensors alongside the railway.