Energy Harvesting Devices Research Articles

Organic Photo‐Responsive Piezoelectric Materials Based on Pyrene Molecules for Flexible Sensors

AbstractDue to the advantages of multiplicity, functionality, and flexibility of organic building blocks, organic piezoelectric materials are regarded as next‐generation materials for potential applications in flexible sensors and energy harvesting devices. Here, a new pure organic pyrene‐based molecule, PyPT is presented, which crystallizes in a non‐centrosymmetric structure. PyPT is synthesized and demonstrated to be suitable for developing flexible sensors due to its remarkable piezoelectric properties. The pyrene‐based piezoelectric molecule exhibits excitation wavelength‐dependent emission behavior and aggregation‐caused quenching properties and demonstrated a piezoelectric coefficient (d33) of 8.02 ± 0.26 pm V−1. The output electronic signal of a PyPT‐based flexible sensor shows a significant increase from 30 to 721 pA as the strain increases from 0.12% to 0.59% with a low Young's modulus of 1.63 Gpa. This high‐performance piezoelectric sensor can serve as a sensitive sound sensor for sound detection and recognition based on the basic characteristics of sound, such as amplitude, frequencies, and timbres. This research offers new insights into advancing pure organic luminescent materials with piezoelectric properties, paving the way for applications in flexible electronics for wearables, human–machine interfaces, and the Internet of Things.

Laser surface processing technology for performance enhancement of TENG

<p>The triboelectric nanogenerator (TENG), as a new energy harvesting device, can efficiently harvest mechanical energy from the environment to provide continuous power for electronic devices, which has great potential for powering intelligent distributed network. Laser processing technology, which enables structural, phase, and property control at different scales, can quickly and easily complete the surface patterning of TENG and facilitate efficient energy harvesting. In this work, we outline the working modes and principles of TENG, review the research progress of laser surface processing technology for fabricating TENG in recent years, including laser-induced graphene (LIG), laser ablation, laser carbonization, laser-induced copper, etc., and perspectives on the challenges and future directions for development of laser surface processing for performance enhancement of TENG.</p>

Novel multi-physics simulation of transient dynamics in functionally graded porous multiferroic cylindrical shells under moving heat flux: A magneto-electro-thermoelastic analysis

Cylindrical structures, such as pipelines in power plants and novel energy-harvesting devices that combine flexible piezoelectric/piezomagnetic layers with other materials, are frequently exposed to moving heat fluxes. Understanding the physics of these structures can provide potential solutions for stress management and energy harvesting. This study investigates, for the first time, the effect of thermal wave propagation on the transient fully coupled magneto-electro-thermoelastic (METE) response of functionally graded porous (FGP) multiferroic cylindrical shells subjected to a partially distributed moving heat flux. The structure is supported by a distributed viscoelastic Winkler-Pasternak foundation, and its mechanical and electromagnetic boundary conditions are considered to be simply supported and suitably grounded. This approach is innovative as it represents the first extension of the three-dimensional (3D) Lord-Shulman coupled thermoelasticity theory to specifically address multiphysics materials. In this updated framework, the governing equations for the motion of each layer are derived following an orthotropic laminated model. To solve the problem, the state-space technique and the mathematical model of the transfer matrix are employed. The study evaluates the structure's vibrational behavior by examining four models of porosity distributions within the thermoelastic layer: symmetric, stiff non-symmetric, soft non-symmetric, and uniform. The key parameters of the dynamic response are calculated using Durbin’s numerical Laplace inversion algorithm. Subsequently, to validate the proposed model, the results are compared with the findings obtained by other researchers. Comprehensive numerical results concerning temporal and spatial variations of temperature, transverse displacement, and stress components are presented for various influencing parameters such as volume fraction index, open or closed-circuit conditions, heat flux speed, porosity, and smart layer thickness.

Enhanced two-temperature model and its application in comprehensive analysis of femtosecond laser melting of gold, copper and their alloys.

Extensive research on ultrashort laser-induced melting of noble metals like Au, Ag and Cu is available. However, studies on laser energy deposition and thermal damage of their alloys, which are currently attracting interest for energy harvesting and storage devices, are limited. This study investigates the melting damage threshold (DT) of three intermetallic alloys of Au and Cu (Au3Cu, AuCu and AuCu3) subjected to single-pulse femtosecond laser irradiation, comparing them with their constituent metals. This is accomplished by extending an earlier-developed two-temperature model (TTM)-based code with several improvements, including precise modeling of temperature-dependent optical properties and ballistic electron transport. The dynamic optical model inclusive of ballistic effects is demonstrated to reproduce the experimental DT of pure metals with minimal variation and is therefore adopted for further investigation. Our simulations reveal that the alloy films have significantly lower incipient and complete melting thresholds compared to the pure metals due to their low thermal conductivity and high electron-phonon coupling strength. Theoretical studies on varying the thickness of metal and alloy films unveil the usual trend of a rapid increase in DT up to a certain thickness, followed by a saturation region. This universal DT profile is elucidated by proposing a first-of-its-kind analytical function. Excellent agreement between the coefficients of the function with optical and electron diffusion parameters derived from the comprehensive theory proposed here reinforces the robustness of the model. The novelty of this study also lies in introducing the concept of a critical film thickness for which the entire film attains the melting temperature at its complete melting threshold.

Advanced functionalization of carbon fiber-reinforced polymer composites towards enhanced hybrid 4-terminal photo-thermal energy harvesting devices by integrating dye-sensitized solar cells and thermoelectric generators

Advanced functionalization of carbon fiber-reinforced polymer composites towards enhanced hybrid 4-terminal photo-thermal energy harvesting devices by integrating dye-sensitized solar cells and thermoelectric generators

Flexible and stable piezoelectric nanogenerators based on monoclinic phase CsPbBr3 perovskite nanocrystals.

CsPbBr3 perovskite has garnered significant attention in the field of optoelectronics due to its exceptional photoelectric properties. In this study, we report the fabrication of a piezoelectric nanogenerator (PNG) composed of a composite of monoclinic phase CsPbBr3 nanocrystals and polydimethylsiloxane. This is the first instance of a PNG based on the monoclinic phase of CsPbBr3. The PNG device has been optimized to operate at a frequency of 30 Hz and exhibits impressive output performance, generating a peak-to-peak output voltage of 50 V, an output current of 5.5 μA and a power density of 2.5 μW cm-2 when subjected to an applied force of only 4.2 N over an effective area of 8 cm2. The energy generated by this PNG can be efficiently collected using capacitors with a high energy conversion efficiency of 21.7%. Furthermore, the output voltage of the PNG remains at 98.5% of its initial value after 20 days, demonstrating exceptional stability. This study highlights the great potential of CsPbBr3 perovskite materials for the simple and cost-effective fabrication of high-performance multifunctional piezoelectric energy harvesting devices.

A Triboelectric Nanogenerator Utilizing a Crank-Rocker Mechanism Combined with a Spring Cantilever Structure for Efficient Energy Harvesting and Self-Powered Sensing Applications

With the advancement of industrial automation, vibrational energy generated by machinery during operation is often underutilized. Developing efficient devices for vibration energy harvesting is thus essential. Triboelectric nanogenerators (TENGs) based on spring and cantilever beam structures show considerable potential for industrial vibration energy harvesting; however, traditional designs often fail to fully harness vibrational energy due to their structural limitations. This study proposes a triboelectric nanogenerator (TENG) based on a crank-rocker mechanism and a spring cantilever structure (CR-SC TENG), which combines a crank-rocker mechanism with a spring cantilever structure, designed for both energy harvesting and self-powered sensing. The CR-SC TENG incorporates a spring cantilever beam, a crank-rocker mechanism, and lever amplification principles, enabling it to respond sensitively to low-frequency, small-amplitude vibrations. Utilizing the crank-rocker and lever effects, this device significantly amplifies micro-amplitudes, enhancing energy capture efficiency and making it well suited for low-amplitude, complex industrial environments. Experimental results demonstrate that this design effectively amplifies micro-vibrations and markedly improves energy conversion efficiency within a frequency range of 1–35 Hz and an amplitude range of 1–3 mm. As a sensor, the CR-SC TENG’s dual-generation units produce output signals that precisely reflect vibration frequencies, making it suitable for the intelligent monitoring of industrial equipment. When placed on an air compressor operating at 25 Hz, the first-generation unit achieved an output voltage of 150 V and a current of 8 μA, while the second-generation unit produced an output voltage of 60 V and a current of 5 μA. These findings suggest that the CR-SC TENG, leveraging spring cantilever beams, crank-rocker mechanisms, and lever amplification, has significant potential for micro-amplitude energy harvesting and could play a key role in smart manufacturing, intelligent factories, and the Internet of Things.

Computational Insights into the Stability, Mechanical, Optoelectronic, and Thermoelectric Characteristics Investigation on Lead‐Based Double Perovskites of (Cs2, K2, Rb2)PbCl6: Promising Candidates for Optoelectronic Applications

AbstractLead‐based double perovskites are studied in the cubic phase using the generalized gradient approximation and the modified Becke–Johnson (mBJ‐GGA) functionals as implemented in the Wien2K code. Goldschmidt tolerance factor and octahedral factor, formation enthalpy, and formation energy translate the structural, chemical, and thermodynamic stability of double perovskites studied. Phonon band structures and elastic moduli ensure the dynamic and mechanical stability of (Cs2, K2, Rb2)PbCl6. An intermediate band appears in the conduction band and the fundamental transition takes place between 3p‐Cl state and 6p‐Pb site. The refractive index of double perovskites (Cs2, K2, Rb2)PbCl6 in the visible and ultraviolet light hold a huge advantage for solar cell applications. The wide dielectric constant of double perovskites under study makes them capable for absorbing energy between 1 and 5 eV, and are suitable for solar power applications. (Cs2, K2, Rb2)PbCl6 have positive Seebeck coefficient, which reveals that p‐type charge carriers are dominant for enhancing their performance. Cs2PbCl6 has positive thermal conductivity for both n‐type and p‐type character. (K2, Rb2)PbCl6 have positive thermal conductivity for n‐type character. The complete analysis reveals that they are potentially significant candidates for future solar cells and energy harvesting devices.

Recent Developments in Electrospun Nanofiber-Based Triboelectric Nanogenerators: Materials, Structure, and Applications.

Triboelectric nanogenerators (TENGs) have garnered significant attention due to their high energy conversion efficiency and extensive application potential in energy harvesting and self-powered devices. Recent advancements in electrospun nanofibers, attributed to their outstanding mechanical properties and tailored surface characteristics, have meant that they can be used as a critical material for enhancing TENGs performance. This review provides a comprehensive overview of the developments in electrospun nanofiber-based TENGs. It begins with an exploration of the fundamental principles behind electrospinning and triboelectricity, followed by a detailed examination of the application and performance of various polymer materials, including poly (vinylidene fluoride) (PVDF), polyamide (PA), thermoplastic polyurethane (TPU), polyacrylonitrile (PAN), and other significant polymers. Furthermore, this review analyzes the influence of diverse structural designs-such as fiber architectures, bionic configurations, and multilayer structures-on the performance of TENGs. Applications across self-powered devices, environmental energy harvesting, and wearable technologies are discussed. The review concludes by highlighting current challenges and outlining future research directions, offering valuable insights for researchers and engineers in the field.

Improved piezoelectric energy harvester with dual-impact strategy for small acceleration amplitude vibrations

Increasing the operable frequency range and improving the small acceleration amplitude harvesting performance of the piezoelectric energy harvesting devices is importance due to the wide frequency spectrum and large amplitude range of environmental vibrations. In this Letter, an improved piezoelectric energy harvester with frequency upconversion is proposed, which is comprised of a composite piezoelectric beam and a firing pin. In contrast to the conventional impact-based systems that mainly rely on beam vibrations to enhance harvesting performance, the proposed system employs a dual-impact strategy. In particular, an oblique impact-based harvesting phenomenon is observed, which has not been investigated in previous studies. A multilevel impact nonlinear coupled dynamic model is developed. The experimental results indicate that at an excitation acceleration amplitude of 0.15 g, the proposed system demonstrates a 482.9% increase in the output peak value and introduces dual-band frequency in comparison with the conventional structure. Additionally, the proposed coupled model is validated through adjustments to various load resistances. The highest output power is achieved at a load resistance of 210 kΩ, with the maximum average power reaching 3.96 mW and a power density of 1.59 mW/mm3g2 at an acceleration amplitude of 0.15 g, outperforming other piezoelectric energy harvesters.

Magnetoelectric effects in a heterostructure of magnetostrictive fiber composite and piezopolymer film

Abstract Magnetoelectric (ME) effects in composite heterostructures comprising ferromagnetic (FM) and piezoelectric (PE) layers realize mutual transformation of magnetic and electric fields and form the basis for the development of highly sensitive magnetic field sensors, electrically tuned electronic components, and energy harvesting devices. ME effects result from a combination of magnetostriction of the FM layer and piezoelectricity in the PE layer due to mechanical coupling between the layers. In this work ME effects are studied in a flexible heterostructure containing a magnetostrictive fiber composite (MFC) and a piezopolymer layer. MFC is a set of microwires made of amorphous FeCoSiB alloy with high magnetostriction and arranged in a plane parallel to each other in a polymer matrix. MFC exhibits strong in-plane anisotropy of magnetization and magnetostriction resulting from demagnetization effects in microwires. Anisotropy leads to the dependence of the linear and nonlinear ME effects characteristics on the orientation of dc magnetic field in the plane of the heterostructure. For the fabricated heterostructure at the resonance frequency of bending vibrations, a linear magnetoelectric coefficient of 24 V/(Oe∙cm) was obtained, and the efficiency of nonlinear generation of the second voltage harmonic reached 1.6 V/(Oe2∙cm). ME effects in MFC heterostructures can be used to create magnetic field sensors and electronics devices that are sensitive to the field orientation.electronics devices that are sensitive to the field orientation.

Performance improvement of a full-scale oscillating water column device by employing a novel double oscillating water column

The energy present in the ocean surface waves can be extracted using an oscillating water column (OWC) device. In the present work, the performance characteristics of a normal OWC, an opposite OWC and a novel double OWC employing Savonius rotors are investigated at different sea states in a numerical wave tank (NWT) using the computational fluid dynamics (CFD) code ANSYS-CFX. The Savonius rotor is known to be an inexpensive energy harvesting device. The waves in the NWT were generated using a piston type wave-maker. The results from the computational work were compared with experimental work. For the normal OWC, a maximum power output of 18.85 kW, which corresponds to an efficiency of 22.44% was recorded at 60 rpm for the mean wave condition. On the other hand, for the opposite OWC, the peak power and efficiency were 10.4 kW and 12.38% respectively for the mean sea state. For the novel double OWC, the flow in the front OWC has more energy compared to the flow in the rear OWC for both advancing flow and retreating flow, resulting in a combined peak power of 19.5 kW at the mean sea state. This represented an increase of 3.45% in the power production.

Theoretical and Experimental Study of Energy-Harvesting and Movement-Sensing Solutions in Pneumatic Systems.

This paper presents an experimentally based study aimed at assessing the viability of employing a commercial energy harvester to develop a self-powered end-stroke and speed sensor for pneumatic cylinders. An energy-harvesting device was integrated into a cylinder end-cap to recover energy from the piston impact at the end of the stroke. The recovered energy powers a radio transmitter that communicates the reach of the end-stroke. This avoids the use of a dedicated end-stroke sensor, reducing the number of components in the system and also saving energy. The experiments aimed to analyze the signal characteristics generated by the module at various activation speeds, assessing whether the impact speed could be distinguished from the signal. Energy output and short-term usage effects were also investigated. The study seeks to further develop and adapt a Simulink model of the system, based on recent studies, and validate it with experimental findings at the tested activation speeds. Following confirmation of the adapted model's validity, the authors propose using genetic algorithms to design an optimized mechanical energy harvester. This approach aims to find the parameters of an energy harvester more suitable for pneumatic cylinder applications that would enable enhanced energy extraction and overall improved performances.

Tapered curved-beam hinges for electret-based vibration energy harvesting devices

Abstract Interests on vibration energy harvesting have been growing recently for various applications. One of the major development goals for vibration energy harvesters has been improvement in energy conversion efficiency. To pursue that goal, one of the main approaches has been to broaden the spectra of harvesters. Employment of nonlinear springs, such as curved-beam hinges, has proven to be effective for that purpose. The main contribution of the current study is to introduce a lateral taper to the curved beam so as to further optimize the harvester performances. Via numerical analysis by using stochastic differential equations, the study shows that at 0.05g of vibration strength, tapered curved-beam hinges can result in higher electric power output than the non-tapered ones. Deformation-induced stress was taken into consideration as well, in reference to the fracture strength of the material (single-crystal silicon). At lower vibration strength (0.02g), spring nonlinearity becomes weaker, and as a result, the narrowest curved-beam hinge produces the highest output power. Overall, the current study demonstrates that tapering of the curved beam can be a useful addition in the vibration energy harvester design.

Fabrication, thermal, mechanical, and piezoelectric characterization of PLA/BT piezocomposites

Abstract The properties of polylactide (PLA) composites containing up to 40 vol% of barium titanate (BT) powder were investigated. PLA/BT composites were fabricated using twin-screw extrusion, which ensured uniform filler dispersion. The results demonstrated that increasing the BT content in PLA improved the thermal stability, stiffness, and degree of crystallinity of the composite. The piezoelectric coefficient d33 also increased with higher BT content and longer polarization times, reaching a maximum value of 35 pC/N for composites containing 40 vol% BT. Additionally, the studies revealed that the d33 coefficient is pressure dependent. Presented PLA/BT piezocomposites highlight the suitability of these materials for applications that require both biocompatibility and piezoelectric functionality, including regenerative medicine, energy harvesting, soft robotics, and electroactive biomedical devices.

Neodymium Doped Zinc Oxide Based Advanced Flexible Piezoelectric Energy Harvester and Self-powered Biomotion Sensor

Flexible piezoelectric devices have garnered a lot of attention for their potential as energy harvesters and transducers. In this work, Neodymium (Nd) doped Zinc Oxide (ZnO) based flexible piezoelectric energy harvester and sensory device has been developed. Nd-doped ZnO has been synthesized using wet chemical co-precipitation and incorporated in Polyvinylidene Difluoride (PVDF) polymer matrix along with Multiwalled Carbon Nanotubes (MWCNT) to produce flexible piezoelectric films. The piezoelectric output of the device is tested at variable tapping frequency (60 to 240 BPM) and pressure (10 to 40 psi). The device has also been tested with conventional electronics like bridge rectifiers, capacitors, resistors, LEDs to show its potential as an energy harvester. Compared to other modified ZnO-PVDF based unpoled piezoelectric energy harvesters, this device has shown the most open-circuit output voltage of 75.8 V and short circuit current of 28.8 µA. It has shown an optimum power density of 12.55 μwcm-2 at 1 MΩ load impedance. Energy harvesting capacity has been further tested by placing the device between the shoe soles during running and jogging. This study endorses the potential of Nd-ZnO/PVDF/MWCNT based piezoelectric energy harvester as the most efficient Piezoelectric Nanogenerator (PENG) which shows superior power generation along with self-powered sensory applications.

Carbohydrate polymer-based triboelectric devices for energy harvesting and intelligent packaging for food-quality monitoring

Carbohydrate polymer-based triboelectric devices for energy harvesting and intelligent packaging for food-quality monitoring

Biodegradable power sources for transient bioelectronics

The development of biodegradable power sources has opened new avenues for transient bioelectronics, offering temporary energy solutions for implantable medical devices. This review presents a systematic overview on the design, materials, and functionalities of biodegradable devices for energy storage, harvesting, and transfer. Biodegradable batteries and supercapacitors provide reliable, short-term energy for implantable devices, while triboelectric and piezoelectric nanogenerators enable continuous energy harvesting from biomechanical sources. Additionally, wireless energy transfer systems enable safe power delivery without direct contact with biological tissues, broadening the scope of implantable bioelectronics. Future research should prioritize enhancing biocompatibility, increasing energy density, and refining degradation control to extend the practical applications of biodegradable power sources in bioelectronics.

Multi-channel wide-angle nonreciprocal thermal radiator with planar heterostructure

From the perspective of application at mid-infrared frequencies, omnidirectional nonreciprocal thermal radiation represents a critical need for effective thermal energy harvesting. In this study, we propose a nonreciprocal thermal radiator (NTR) which can be fabricated with a lithography-free approach. The structure is composed by germanium(Ge)-aluminum nitride(AlN)-Weyl semimetal (WSM) stacks and terminated with a metallic substrate. The results indicate that both the magnitude and the sign of the contrast between emission (e) and absorption (α) can be manipulated. This design achieves multi-channel nonreciprocal stability for transverse magnetic (TM) polarized incident wave over an exceptionally wide angular range. Additionally, the electromagnetic field distributions at the resonance wavelengths have been analyzed to elucidate the underlying principles. Multi-band nonreciprocity under transverse electric (TE) polarized incident wave has also been obtained. The capability of our proposal offers a relatively straightforward method to realize high-performance NTR. This advancement holds potential implications for the development of efficient energy harvesting and conversion devices.

Enhanced Piezoelectric Properties of Poly(L‐lactide) Nanocomposite Microfiber Scaffolds Due to Polydopamine‐Coating of Barium Titanate Nanoparticles

AbstractRecent biomedical applications demand piezoelectric polylactide (PLA)‐based polymers, possessing biodegradable and biocompatible properties for tissue regeneration, implantable force sensors, and energy harvesting devices. However, piezoelectric poly(L‐lactide) (PLLA) possesses weak piezoelectric properties in comparison to non‐biodegradable poly(vinylidene fluoride) (PVDF), limiting its application. This contribution presents, for the first time, a nanocomposite strategy to enhance the piezoelectric properties of PLLA, while maintaining cytocompatibility. Biocompatible and piezoelectric barium titanate (BTO) nanoparticles (NPs) are coated by polydopamine (PDA) (cBTO NPs) to improve the quality of the matrix‐filler interface and enhanced the force transmission toward the BTO NPs. Electrospun PLLA/cBTO nanocomposite microfiber scaffolds with 5 wt% of PDA‐coated BTO NPs (cBTO) exhibited an increase in piezoelectric properties of 120% in comparison to pristine PLLA microfiber scaffolds, implying a voltage output increase from 1.4 ± 0.1 to 3.2 ± 0.2 V. Furthermore, the PDA‐coating of BTO (cBTO) NPs itself has an intensifying impact on the piezoelectric properties of PLLA/cBTO nanocomposite compared to non‐coated BTO NPs, increasing the voltage output by 41%. This demonstrates the great potential of PDA‐coating of piezoelectric NPs to enhance the piezoelectric response of PLLA.