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To bring the rapidly advancing technology of energy harvesters into commercial use, further development is required for devices that can enhance output performance, flexibility, ease of fabrication, and low cost. A hybrid concept is a promising method. It combines between the piezoelectric nanogenerator (PENG) and the triboelectric nanogenerator (TENG) to provide a high-performance nanogenerator. This study introduced a high-performance hybrid PENG and TENG device that operates using a NN-BNT/PDMS composite film. The NN-BNT/PDMS composite based nanogenerators were fabricated with varying NN-BNT content. Then, dielectric test and electrical properties were investigated. Adding NN-BNT into the PDMS composite film resulted in a higher dielectric constant compared to pure PDMS, leading to increase of electrical output. Under the optimal condition of a 3 wt%. NN-BNT composite based hybrid nanogenerator, the electrical output was significantly enhanced, reaching 40 V, 0.95 μA/cm2, and 200 μW/cm2 compared to pure PDMS. This nanogenerator further used to the charging of a capacitor to a voltage of around 1 V within 5 s and also powered multiple LEDs. The successful development of this highly efficient NN-BNT/PDMS composite film-based hybrid concept sheds light on energy harvesting devices. [ABSTRACT FROM AUTHOR]

Flow‐induced vibrations (FIVs) serve as the fundamental principle of non‐rotary wind energy harvesting. However, nanogenerators relying on a single FIV effect remain constrained by insufficient breeze energy conversion efficiency. In this paper, we propose a novel galloping‐flutter coupled nanogenerator (GFNG) that leverages the synergistic interaction between these two aerodynamic phenomena, to achieve high performance across broad wind speed bandwidth. A galloping‐flutter coupled mechanism (GFM) is implemented using a multifunctional flexible beam that integrates a galloping piezoelectric energy harvester (GPEH) and a fluttering triboelectric nanogenerator (FTENG). Through meticulous optimization, it significantly enhances the average electrical output of the FTENG by up to six times at low wind speeds below 6 m s−1, by intensifying the triboelectric contact behavior through galloping‐induced beam oscillations. The GFNG demonstrates a maximum average power of 6.3 mW across wind speeds from 1.4 to 10 m s−1, along with a remarkable power density of 7.1 W m−2 of the enhanced FTENG at 10 m s−1, enabling the lighting of 508 LEDs and stable power supply for wireless sensor nodes (WSNs). This study offers new insights into designing high‐performance aerodynamics‐driven nanogenerators by harnessing multiple FIV synergistic effects, broadening the potential for intelligent wind energy applications. [ABSTRACT FROM AUTHOR]

To mitigate the risks posed by noncommunicable chronic diseases (NCDs) to human health, the Internet of Healthcare (IoH) requires sensors with real‐time and long‐term monitoring capabilities. However, traditional pressure sensors, due to their high‐power consumption and non‐rechargeability, are unbale to meet the increasingly stringent requirements of physiological monitoring devices in the IoH. The emergence of self‐powered pressure sensing technology, exemplified by nanogenerators, provides a new strategy for the next generation of wearable health monitoring devices. This review begins by discussing the merits and drawbacks of different pressure‐sensing modes for healthcare monitoring. Then, it introduces the development and working mechanism of self‐powered triboelectric and piezoelectric sensors. Furthermore, it summarizes the optimizations of sensor structure and material selection aimed at improving sensing performance and achieving high accuracy in sensor networks within the IoH. Relevant application based on independent, or hybrid mechanisms are also covered. Finally, the challenges and prospects for achieving large‐scale commercial applications of self‐power sensing system in IoH are discussed. [ABSTRACT FROM AUTHOR]

In recent years, the automotive industry has made significant progress in integrating multifunctional sensors to improve vehicle performance, safety, and efficiency. As the number of integrated sensors keeps increasing, there is a growing interest in alternative energy sources. Specifically, self‐powered sensor systems based on energy harvesting are drawing much attention, with a main focus on sustainability and reducing reliance on typical batteries. This paper demonstrates the use of triboelectric nanogenerators (TENGs) in a computer mouse for efficient energy harvesting and in automobile braking systems for safety applications using SrBi2Ta2O9 (SBTO) perovskite, blended PDMS composite operating in free‐standing mode with an interdigitated patterned aluminum electrode. This self‐powered sensor is capable of distinguishing between normal and abnormal braking patterns using digital signal processing techniques. It is noteworthy that the addition of 15% wt. of the SBTO in PDMS composite‐based TENG delivered 13.5 V, 45 nA, and an output power of 0.98 µW. This new combination of energy harvesting and safety applications enables real‐time monitoring and predictive maintenance in the automotive industry. [ABSTRACT FROM AUTHOR]

Subhasmita Swain,1 RDK Misra,2 Tapash R Rautray1 1Biomaterials and Tissue Regeneration Laboratory, Centre of Excellence, Siksha ‘O’ Anusandhan (Deemed to be University), Bhubaneswar, Odisha, India; 2Metallurgical, Materials and Biomedical Engineering Department, The University of Texas at El Paso, El Paso, Texas, 79968, USACorrespondence: Tapash R Rautray; RDK Misra, Email tapashrautray@soa.ac.in; dmisra2@utep.eduAbstract: Electroactive components can promote tissue healing and control neuronal activity with the support of the tissue environment and offer electrical impulses and biocompatible material habitats. Due to the increasing growth of portable electronics, it is imperative to generate tiny, lightweight power supply appliances with outstanding performance and sustainable energy conversion ability. In order to deal with the energy deficiency of electronic devices, self-powered systems based nanogenerators are committed to capturing ambient energy for electronic device consumption. Nanogenerator assemblies provide a range of benefits, including adjustable shape, flexibility, affordability, and transportability. As such, they represent a novel and intriguing area for biomedical investigation. In living organisms, bioelectrical mechanisms play an integral part in regulating the functions of cells and tissues. An essential component of electroactive assemblies includes self-powered nanogenerators. In conjunction with nanogenerators, biomedicine has contributed to the invention of medical devices based on self-powered system. Currently, one of the most significant energy-based technologies to guarantee the long-term functioning of implanted biomedical devices is the accumulation of biomechanical energy in vivo. This review covers the development of nanogenerators for biomedical applications. Piezoelectric and triboelectric materials, which could foster the evolution of potential applications in the field of bone regeneration and tissue engineering, are the primary focus of this review. These materials are electrically self-sustaining generators that encourage tissue repair involving osteogenic proliferation, differentiation, and microbial sterilization. Eventually, the discussion highlights the potential future scope and challenges related to the nanogenerators.Keywords: nanogenerator, piezoelectric, triboelectric, tissue engineering

The rise of the Internet of things has catalyzed extensive research in the realm of flexible wearable sensors. In comparison with conventional sensor power supply methods that are reliant on external sources, self-powered sensors offer notable advantages in wearable comfort, device structure, and functional expansion. The energy-harvesting modes dominated by piezoelectric nanogenerators (PENGs), triboelectric nanogenerators (TENGs), and pyroelectric nanogenerators (PyENGs) create more possibilities for flexible self-powered sensors. This paper meticulously examines the progress in flexible self-powered devices harnessing TENG, PENG, and PyENG technologies and highlights the evolution of these sensors concerning the material selection, pioneering manufacturing techniques, and device architecture. It also focuses on the research progress of sensors with composite power generation modes. By amalgamating pivotal discoveries and emerging trends, this review not only furnishes a comprehensive portrayal of the present landscape but also accentuates avenues for future research and the application of flexible self-powered sensor technology.

Triboelectric nanogenerators (TENGs) hold immense potential as sustainable energy sources, with waste materials serving as promising materials for their fabrication. Nearly 270 million tons of waste is produced yearly, most of which remains unrecycled. TENGs can utilize this wide range of waste to convert mechanical energy to electrical energy while providing a solution for the global issue of plastic waste. On the other hand, the enormous demand for wearable electronics and the Internet of Things (IoT) trigger the development of self‐reliant energy sources. Currently, TENGs are one of the preferred choices as they are easy to design and generate high output. In this regard, TENGs are promising for utilizing waste materials, particularly for self‐powered or energy‐autonomous applications. This review focuses on utilizing waste materials from diverse sources, including biowaste, household waste, medical, laboratory, pharmaceutical, textile, electronic waste (e‐waste), and automotive waste for TENG development. Different waste materials are detailed for their potential as materials for TENGs, their availability, and recycling methods. The review also highlights the applications of TENGs fabricated from waste materials. Finally, the challenges, limitations, and future perspectives of using waste materials for TENG fabrication are discussed to motivate further advances. [ABSTRACT FROM AUTHOR]

The development of triboelectric nanogenerators (TENGs) using sustainable materials addresses the global electronic waste issue. This research focuses on fabricating a TENG device with biodegradable polylactic acid (PLA) as the tribopositive material and polytetrafluoroethylene (PTFE) as the tribonegative material. ZnFe2O4 nanoparticles are incorporated into the PLA matrix to enhance surface charge density and synthesised via a simple combustion method. PLA-ZnFe2O4 composite films were prepared by solvent casting with varying nanofiller content (0.25, 0.45, 0.65, and 0.85 g). Prepared composites were characterised by Powder X-ray Diffraction (PXRD) for crystalline nature and phase purity, Fourier Transform Infrared Spectroscopy (FTIR) for vibrational analysis, and Scanning Electron Microscopy (SEM) for surface morphology. The inclusion of ZnFe2O4 nanoparticles improves TENG output performance, with a maximum output voltage of 18.4 V and a current of 1.57 µA observed for a PLA (poly(lactic acid)) composite with 39.39% nanoparticle content. Electrical studies on the optimised device show successful charging of various capacitors and powering 20 LEDs and a calculator. Body movements like walking and jumping were also tested to measure voltage and current outputs. These findings highlight new possibilities for developing smart, self-powered electronic devices. [ABSTRACT FROM AUTHOR]

Hybrid nanogenerators are advanced mechanical energy harvesters capable of simultaneously scavenging multiple types of energy. Additionally, thermochromic materials provide a practical and visually assessable method for real‐time temperature monitoring. In this report, a novel energy harvester and sensing patch (EHSP) is introduced, that utilizes combined piezoelectric and triboelectric effects to harvest mechanical energy efficiently. To optimize the EHSP, various energy harvester configurations are fabricated and tested, and the dielectric properties of triboelectric films are systematically investigated. These improvements are implemented to augment the overall energy harvesting capability. The thermochromic properties of the EHSP are also explored to enhance both the electrical performance and thermal responsiveness. The EHSP demonstrates the ability to generate maximum voltage and current outputs of 350 V and 20.4 µA, respectively. Moreover, it can detect temperature changes within seconds, making it suitable for both energy harvesting and sensing applications. The EHSP is tested in practical scenarios, proving its efficiency as an energy harvester and sensor for everyday human activities. Furthermore, its integration with multiple hybrid nanogenerators showcases its potential for industrial and wearable sensing applications. [ABSTRACT FROM AUTHOR]

The rise of the Internet of things has catalyzed extensive research in the realm of flexible wearable sensors. In comparison with conventional sensor power supply methods that are reliant on external sources, self-powered sensors offer notable advantages in wearable comfort, device structure, and functional expansion. The energy-harvesting modes dominated by piezoelectric nanogenerators (PENGs), triboelectric nanogenerators (TENGs), and pyroelectric nanogenerators (PyENGs) create more possibilities for flexible self-powered sensors. This paper meticulously examines the progress in flexible self-powered devices harnessing TENG, PENG, and PyENG technologies and highlights the evolution of these sensors concerning the material selection, pioneering manufacturing techniques, and device architecture. It also focuses on the research progress of sensors with composite power generation modes. By amalgamating pivotal discoveries and emerging trends, this review not only furnishes a comprehensive portrayal of the present landscape but also accentuates avenues for future research and the application of flexible self-powered sensor technology. [ABSTRACT FROM AUTHOR]

Polystyrene (PS) is a very common material in packaging. In this study, it is recycled by turning it into energy harvesting devices: triboelectric generators. Herein, heat‐pressed films of recycled PS are formed and their surfaces are modified physically and chemically. The triboelectric properties of the films are determined using a dynamic testing machine, and the performance of the triboelectric generators is evaluated with a high‐speed contact–separation system. The developed charge density of the triboelectric generator increases two orders of magnitude—from 0.03 to 1.52 nC cm−2—by combining these surface modification methods. Such high values of charge density enable the production of single material triboelectric generators. [ABSTRACT FROM AUTHOR]

Wireless energy transfer (WET) based on ultrasound‐driven generators with enormous beneficial functions, is technologically in progress by the valuation of ultrasonic metamaterials (UMMs) in science and engineering domains. Indeed, novel metamaterial structures can develop the efficiency of mechanical and physical features of ultrasound energy receivers (US‐ETs), including ultrasound‐driven piezoelectric and triboelectric nanogenerators (US‐PENGs and US‐TENGs) for advantageous applications. This review article first summarizes the fundamentals, classification, and design engineering of UMMs after introducing ultrasound energy for WET technology. In addition to addressing using UMMs, the topical progress of innovative UMMs in US‐ETs is conceptually presented. Moreover, the advanced approaches of metamaterials are reported in the categorized applications of US‐PENGs and US‐TENGs. Finally, some current perspectives and encounters of UMMs in US‐ETs are offered. With this objective in mind, this review explores the potential revolution of reliable integrated energy transfer systems through the transformation of metamaterials into ultrasound‐driven active mediums for generators. [ABSTRACT FROM AUTHOR]

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

Recent developments in robotics increasingly highlight the importance of sensing technology, especially tactile perception, in enabling robots to effectively engage with their environment and interpret physical interactions. Due to power efficiency and low cost, the triboelectric mechanism has been frequently studied for measuring pressure and identifying materials to enhance robot perception. Nevertheless, there has been limited exploration of using the triboelectric effect to detect curved surfaces, despite their prevalence in daily lives. Here, a triboelectric multimodal tactile sensor (TMTS) of multilayered structural design is proposed to recognize distinct materials, curvatures, and pressure simultaneously, thus decoupling different modalities to enable more accurate detection. By attaching sensors to robotic fingertips and leveraging deep learning analytics, the quantitative curvature measurement provides more precise insights into an object's detailed geometric characteristics rather than merely assessing its overall shape, hence achieving automatic recognition of 12 grasped objects with 99.2% accuracy. The sensor can be further used to accurately recognize the softness of objects under different touch gestures of a robotic hand, achieving a 94.1% accuracy, demonstrating its significant potential for wide‐ranging applications in a future robotic‐enabled intelligent society. [ABSTRACT FROM AUTHOR]

The porous structure formed by the interweaving of yarns in textiles is favorable for sound absorption. However, the absorption of sound waves by porous materials conforms to the law of linear response, which leads to poor sound absorption of textiles in the low-frequency range. It is usually necessary to increase the thickness to improve the low-frequency acoustic absorption performance of textiles, which does not meet the performance requirements of lightness, thinness, width and strength. This work proposes a method to increase the acoustic absorption performance based on acoustic-electric conversion and yarn resonance effect. In the form of a woven spacer fabric structure, different parts of the structure were prepared using nylon and PVDF yarns with different triboelectric sequences to realize acoustic-electric conversion between dielectric materials. Control samples woven with the same material were also prepared. Further, the resonance frequency of the yarns was modulated by controlling their tension to change the resonant frequency corresponding to the maximum acoustic-electric conversion efficiency and sound absorption peak. It was found that fabrics composed of two different materials had better sound absorption than fabrics composed of only one material. This is because the larger triboelectric sequence difference between materials results in more charge transfer, which favors acoustic-electric conversion and acoustic energy consumption. A significant acoustic absorption peak at 390 Hz with a peak value of about 0.05 was observed for a fabric with a thickness of about 4 mm after tension adjustment. This study demonstrates that acoustic-electric conversion between dielectric yarns and proper tension control improves the acoustic absorption efficiency and provides a reference for the development of structures based on this novel acoustic absorption mechanism. [ABSTRACT FROM AUTHOR]

Within electrical contacts, poor electrical conductivity of lubricants can lead to triboelectric charging, causing electrostatic currents and thermal effects, which accelerate lubrication failure. This study aimed to address these challenges by producing and testing three greases with different base oils: ionic liquid ([Oley][Oleic]), synthetic oil (PAO4), and vegetable oil-based synthetic ester (trimethylolpropane oleate). Each grease was prepared with polytetrafluoroethylene powder as the thickener. The greases were tested using a custom-made tribometer, integrated with a grounded electrical current system, with friction tests conducted with up to a 2 A electrical current flow at a constant voltage supply of 4.5 V. Under triboelectric friction testing, [Oley][Oleic] grease outperformed a commercial perfluoropolyether grease by 27.7% in friction and 16.3% in wear. This grease also showed better performance than formulated lithium grease with extreme pressure additives. The study demonstrates that greases with low interfacial resistance can retain their lubrication capacity under triboelectric conditions. These results indicate that [Oley][Oleic] grease, with its ionic liquid base oil, offers a promising solution for applications involving electrical contacts. This study highlights the potential of using advanced base oils and thickeners to enhance the performance and sustainability of lubricants in demanding environments. [ABSTRACT FROM AUTHOR]

Multi‐dimensional force sensing that combines intensity, location, area and the like could gather a wealth of information from mechanical stimuli. Developing materials with force‐induced optical and electrical dual responses would provide unique opportunities to multi‐dimensional force sensing, with electrical signals quantifying the force amplitude and the luminescence output providing spatial distribution of force. However, the reliance on external power supply and high‐energy excitation source brings significant challenges to the applicability of multi‐dimensional force sensors. Here we reported the mechanical energy‐driven and sunlight‐activated materials with force‐induced dual responses, and investigated the underlying mechanisms of self‐sustainable force sensing. Theoretical analysis and experimental data unraveled that trap‐controlled luminescence and interfacial electron transfer play a major role in force‐induced optical and electrical output. These materials were manufactured into pressure sensor with renewable dual‐mode output for quantifying and visualization of pressures by electrical and optical output, respectively, without power supply and high‐energy irradiation. The quantification of tactile sensation and stimuli localization of mice highlighted the multi‐dimensional sensing ability of the sensor. Overall, this self‐powered pressure sensor with multimodal output provides more modalities of force sensing, poised to change the way that intelligent devices sense with the world. [ABSTRACT FROM AUTHOR]

Developing energy harvesting devices is crucial to mitigate the dependence on conventional and rigid batteries in wearable electronics, ensuring their autonomous operation. Nanogenerators offer a cost‐effective solution for enabling continuous operation of wearable electronics. Herein, this study proposes a novel strategy that combines freeze‐casting, freeze‐drying, and printing technologies to fabricate a fully printed triboelectric nanogenerator (TENG) based on polyvinylidene fluorid‐etrifluoroethylene P(VDF‐TrFE) porous aerogel. First, the effects of porosity and poling on the stretchability and energy harvesting capabilities of P(VDF‐TrFE) are investigated, conducting a comprehensive analysis of this porous structure's impact on the mechanical, ferroelectric, and triboelectric properties compared to solid P(VDF‐TrFE) films. The results demonstrate that structural modification of P(VDF‐TrFE) significantly enhances stretchability increasing it from 7.7% (solid) to 66.4% (porous). This modification enhances output voltage by 66% and generated charges by 48% for non‐poled P(VDF‐TrFE) porous aerogel films compared to their non‐poled solid counterparts. Then, a fully printed TENG is demonstrated using stretchable materials, exhibiting a peak power of 62.8 mW m−2 and an average power of 9.9 mW m−2 over 100 tapping cycles at 0.75 Hz. It can illuminate light‐emitting diodes (LEDs) through the harvesting of mechanical energy from human motion. This study provides a significant advance in the development of energy harvesting devices. [ABSTRACT FROM AUTHOR]

The triboelectric effect has recently showcased significant potential in environmental remediation applications. It has been employed to initiate various catalytic reactions through the utilization of minimal mechanical energy. In this context, the present study focuses on the tribocatalytic activity of LiNbO 3 powder prepared via solid-state reaction process. From the study, it was found that ∼92 % of Rhodamine B (RB) dye was degraded in 15 h of mechanical stirring. The results showed that there is significant influence of each parameter in the tribocatalysis process. The current study systematically explored the connection between various affecting parameters and the tribocatalysis mechanism by using LiNbO 3 ceramic whereby laying a robust foundation for the advancement of tribocatalysis process. [ABSTRACT FROM AUTHOR]

Humans generate a lot of irregular movements in their daily lives, and much of the movement energy is difficult to collect. This paper develops a wearable device based on a liquid metal (LM)‐based frictional electric nanogenerator, including: flexible power‐generating fiber, power‐generating surface, and power‐generating insole. Friction nano power generation fibers are prepared using LM, epoxy resin, and silicone. The power generation device could be formed by weaving the fibers in cross, mesh and spiral arrangement, with a maximum open circuit voltage of 142 mV and current of 1.06 A, which could be coded into intelligent clothing. Power generating surfaces use LM, nylon,polycaprolactone (PCL), and polyethylene terephthalate (PET) as friction electrodes. The LM‐PCL produces a maximum open‐circuit voltage of 2.4 V and a maximum current of 1.23 A when they form a friction electrode. Electricity‐generating insoles are composed of silicone holes filled with LM, and the movement of the human foot generates electricity. With a friction area of 18.75 cm2, a maximum output voltage of 221 mV is obtained. These friction nano power devices have the advantages of a green environment, and low cost, which could be widely used in medical, biological, and clothing formulation fields. [ABSTRACT FROM AUTHOR]

Flexible piezoelectric nanogenerator (PENG) and triboelectric nanogenerators (TENG) have gained prodigious attention due to the increasing demand of nano and micro energy for driving of miniaturized electronic devices, sensors, and various internet of things. The key challenges that are currently in focus are material selection and simple fabrication techniques for improved electrical performance along with good mechanical properties and flexibility. Herein, a ferroelectric polymer, poly(vinylidenefluoride-co-trifluoroethyne) (PVDF-TrFE), is chosen as a flexible material due to its promising prospect for energy harvesting. To improve the performance, a ceramic material, 0.65Pb(Mg1/3Nb2/3)O3–0.35PbTiO3 (PMN-PT), with very high piezoelectric properties has been selected as the reinforcement. Further, reduced graphene oxide has been added as a conducting filler to promote charge conduction. A remarkable enhancement in output voltage of nearly 3 fold is achieved in PVDF-TrFE/PMN-PT (PP) polymer composite as compared to the base polymer PVDF-TrFE (P) TENG device. Furthermore, the PVDF-TrFE/rGO/PMN-PT (PPR) as a PENG illustrates a great improvement in output current of the order of 2 as compared to the pristine polymer. The maximum output voltage as shown by the TENG is 200 V and the maximum current that is shown by the PENG is 30 µA. Therefore, the fabricated PMN-PT based PVDF-TrFE nanogenerators have an immense prospect for applications in self-powered systems.

Abstract Wireless energy transfer (WET) based on ultrasound‐driven generators with enormous beneficial functions, is technologically in progress by the valuation of ultrasonic metamaterials (UMMs) in science and engineering domains. Indeed, novel metamaterial structures can develop the efficiency of mechanical and physical features of ultrasound energy receivers (US‐ETs), including ultrasound‐driven piezoelectric and triboelectric nanogenerators (US‐PENGs and US‐TENGs) for advantageous applications. This review article first summarizes the fundamentals, classification, and design engineering of UMMs after introducing ultrasound energy for WET technology. In addition to addressing using UMMs, the topical progress of innovative UMMs in US‐ETs is conceptually presented. Moreover, the advanced approaches of metamaterials are reported in the categorized applications of US‐PENGs and US‐TENGs. Finally, some current perspectives and encounters of UMMs in US‐ETs are offered. With this objective in mind, this review explores the potential revolution of reliable integrated energy transfer systems through the transformation of metamaterials into ultrasound‐driven active mediums for generators.

Abstract Kelvin probe force microscopy (KPFM) is a well‐established scanning probe technique, used to measure surface potential accurately; it has found extensive use in the study of a range of materials phenomena. In its conventional form, KPFM frustratingly precludes imaging samples or scenarios where large surface potential or surface potential gradients exist outside the typical ±10 V window. If the potential regime measurable via KPFM can be expanded, to enable precise and reliable metrology, through a high voltage KPFM (HV‐KPFM) adaptation, it can open up pathways toward a range of novel experiments, where the detection limit of regular KPFM has so far prevented the use of the technique. In this work, HV‐KPFM is realized and shown to be capable of measuring large surface potential and potential gradients with accuracy and precision. The technique is employed to study a range of materials (positive temperature coefficient of resistivity ceramics, charge storage fluoropolymers, and pyroelectrics) where accurate, spatially resolved mapping of surface potential within high voltage regime facilitates novel physical insight. The results demonstrate that HV‐KPFM can be used as an effective tool to fill in existing gaps in surface potential measurements while also opening routes for novel studies in materials physics.

Developing metal-free electrodes for prototypes of bio-based devices is an essential step in producing non-toxic components for implantable devices and wearables. In particular, the advancement in self-powered devices is a hot topic for several applications due to the possibility of creating free-battery devices and sensors. In this paper, the modification of bacterial cellulose by the progressive incorporation of carbon black (a conductive filler) was explored as a prototype for bio-based electrodes for triboelectric nanogenerators. This process was controlled by the percolation pathways’ activation through the contact of carbon black grains with the bacterial cellulose membrane, which represents a critical step in the overall process of optimization in the power output performance, reaching an open circuit voltage value of 102.3 V, short circuit current of 2 μA, and power density of 4.89 μW/cm2.

Developing metal-free electrodes for prototypes of bio-based devices is an essential step in producing non-toxic components for implantable devices and wearables. In particular, the advancement in self-powered devices is a hot topic for several applications due to the possibility of creating free-battery devices and sensors. In this paper, the modification of bacterial cellulose by the progressive incorporation of carbon black (a conductive filler) was explored as a prototype for bio-based electrodes for triboelectric nanogenerators. This process was controlled by the percolation pathways' activation through the contact of carbon black grains with the bacterial cellulose membrane, which represents a critical step in the overall process of optimization in the power output performance, reaching an open circuit voltage value of 102.3 V, short circuit current of 2 μA, and power density of 4.89 μW/cm2. [ABSTRACT FROM AUTHOR]

The ferroelectric‐semiconductor behavior of antimony sulfoiodide (SbSI) has opened up the material as a base for energy‐harvesting devices. Specifically, SbSI has drawn much attention for pyroelectric energy harvesting and thermal sensing with outstanding electrothermal properties. This work investigates the thermistor properties of an SbSI material and presents the development of an SbSI nanorod/Kapton‐based triboelectric nanogenerator (TENG) for effective energy harvesting and temperature sensing. The TENG based on SbSI/ Kapton operating in vertical contact separation mode delivers a peak‐to‐peak voltage of 90 V and a current of 1510 nA, respectively. Introducing SbSI nanorods for TENG opens the possibility of extending the conventional triboelectric series. The electrical and dielectric properties of the SbSI nanorods are investigated. SbSI exhibits a highly linear temperature coefficient of resistance (TCR) of −0.026 °C−1, making it an excellent candidate material for a thermistor. In addition, the material exhibits an excellent thermal sensitivity (β20/80 = 1612.1 K). For demonstration, the SbSI thermistor is connected with TENG, and the outputs at various temperatures are analyzed for self‐powered temperature sensing. This capability allows for efficient temperature monitoring without relying on external power sources, advancing remote, and autonomous sensing applications. [ABSTRACT FROM AUTHOR]

Harvesting the dissipated environmental mechanical energy to generate electrical energy is subject of the new research in the field of clean energy. In this paper, a triboelectric nanogenerator based on vertical two-electrode structure was fabricated using KAPTON and PDMS polymers. The nanogenerator outputs were measured and plotted by applying a mechanical vibration with the frequency of 8 Hz. The results indicated the ability of producing a voltage of 3.5 V and a current of 0.025 μA by this nanogenerator. To effectively simulate the performance of the device in different structural and environmental conditions, the ordinary capacitance model of the device was modified considering three effective capacitances. The simulation results showed a very good agreement between calculated and actual outputs when the edge effect capacitor was included in the ordinary model. Finally, based on the corrected model for the nanogenerator, the effect of the environmental conditions on the device output was studied. The innovative point of this text is the investigation of the effect of edge capacitors in the performance of triboelectric nanogenerators, and it has also been tried to collect a collection of studies that I have done in the field of triboelectric nanogenerators. [ABSTRACT FROM AUTHOR]

Energy harvesting systems, including piezoelectric (PENG), triboelectric (TENG), and pyroelectric (PYNG) nanogenerator technologies, have emerged as one of the major future energy solutions. Energy harvesting eliminates the need for conventional batteries and encourages eco-friendly alternatives. This study reports hydrothermally synthesized BaTiO3 (BTO) particles with a tetragonal symmetry for hybrid energy harvesting. BTO particles are incorporated with PDMS at various wt% to form a flexible composite film. The 15 wt% BTO-PDMS composite/Al hybrid device (PENG-TENG) produces a peak voltage of 100 V, a current of 980 nA, and a charge of 17 nC, generating a peak power output of 33.64 μW at 100 MΩ. Furthermore, integrating this HNG (external hybridization) yielded an output of 101 V and 980 nA, demonstrating practical applicability. HNG is also employed to interact by touching various objects at different temperatures. The pyroelectric behavior of BTO allows direct thermal sensing of the object. The signals produced are processed using a convolutional neural network (CNN)-based object recognition system, which achieved a remarkable classification accuracy of 99.27% for various objects. External hybridization improves energy efficiency, representing a huge step forward in sustainable technology applications. This research paves the way for developing hybrid energy harvesters and can be employed further for extremely precise battery-free object recognition systems. This unique hybrid nanogenerator, which combines pyroelectric, piezoelectric, and triboelectric components, represents a new method of self-powered object detection. External hybridization improves energy efficiency, representing a huge step forward in sustainable technology applications.

Collecting ambient energy to power various wearable electronics is considered a prospective approach to addressing their energy consumption. Mechanical and thermal energies are abundantly available in the environment and can be efficiently converted into electricity based on different physical effects. Hydrogel-based energy harvesters have turned out to be a promising solution, owing to their unique properties including flexibility and biocompatibility. In this review, we provide a concise overview of the methods and achievements in hydrogel-based energy harvesters, including triboelectric nanogenerators, piezoelectric nanogenerators, and thermoelectric generators, demonstrating their applications in power generation, such as LED lighting and capacitor charging. Furthermore, we specifically focus on their applications in self-powered wearables, such as detecting human motion/respiration states, monitoring joint flexion, promoting wound healing, and recording temperature. In addition, we discuss the progress in the sensing applications of hydrogel-based self-powered electronics by hybridizing multiple energy conversion in the field of wearables. This review analyzes hydrogel-based energy harvesters and their applications in self-powered sensing for wearable devices, with the aim of stimulating ongoing advancements in the field of smart sensors and intelligent electronics.

Within electrical contacts, poor electrical conductivity of lubricants can lead to triboelectric charging, causing electrostatic currents and thermal effects, which accelerate lubrication failure. This study aimed to address these challenges by producing and testing three greases with different base oils: ionic liquid ([Oley][Oleic]), synthetic oil (PAO4), and vegetable oil-based synthetic ester (trimethylolpropane oleate). Each grease was prepared with polytetrafluoroethylene powder as the thickener. The greases were tested using a custom-made tribometer, integrated with a grounded electrical current system, with friction tests conducted with up to a 2 A electrical current flow at a constant voltage supply of 4.5 V. Under triboelectric friction testing, [Oley][Oleic] grease outperformed a commercial perfluoropolyether grease by 27.7% in friction and 16.3% in wear. This grease also showed better performance than formulated lithium grease with extreme pressure additives. The study demonstrates that greases with low interfacial resistance can retain their lubrication capacity under triboelectric conditions. These results indicate that [Oley][Oleic] grease, with its ionic liquid base oil, offers a promising solution for applications involving electrical contacts. This study highlights the potential of using advanced base oils and thickeners to enhance the performance and sustainability of lubricants in demanding environments.

Collecting ambient energy to power various wearable electronics is considered a prospective approach to addressing their energy consumption. Mechanical and thermal energies are abundantly available in the environment and can be efficiently converted into electricity based on different physical effects. Hydrogel-based energy harvesters have turned out to be a promising solution, owing to their unique properties including flexibility and biocompatibility. In this review, we provide a concise overview of the methods and achievements in hydrogel-based energy harvesters, including triboelectric nanogenerators, piezoelectric nanogenerators, and thermoelectric generators, demonstrating their applications in power generation, such as LED lighting and capacitor charging. Furthermore, we specifically focus on their applications in self-powered wearables, such as detecting human motion/respiration states, monitoring joint flexion, promoting wound healing, and recording temperature. In addition, we discuss the progress in the sensing applications of hydrogel-based self-powered electronics by hybridizing multiple energy conversion in the field of wearables. This review analyzes hydrogel-based energy harvesters and their applications in self-powered sensing for wearable devices, with the aim of stimulating ongoing advancements in the field of smart sensors and intelligent electronics. [ABSTRACT FROM AUTHOR]

The flexible polyvinylidene difluoride (PVDF)/6H–SiC composite films are fabricated to overcome the natural brittleness of hexagonal SiC. Yet the electrical output of the piezoelectric nanogenerator (PENG) based on the composite film needs to be further improved. Here, PENG and hybrid nanogenerator exploiting both triboelectric and piezoelectric effects (T-PENG) based on PVDF/6H–SiC composite films are assembled. The PENG based on the PVDF/15 wt% 6H–SiC composite film shows the open circuit voltage (V oc) of 16.81 V. The T-PENG achieves the bridge rectified voltage of 65.70 and 136.58 V when subjected to the external force of 1.1 and 4.9 N, indicating 3.91 and 7.39 times the output of the PENG under the same force, which is the highest value compared with the reported nanogenerators based on SiC and SiC composites. This work breaks through the limitation of low mechanical energy utilization efficiency of film-based PENG and provides a feasible way to enhance the electrical output of nano power sources. [ABSTRACT FROM AUTHOR]

Wound healing is a highly orchestrated biological process characterized by sequential phases involving inflammation, proliferation, and tissue remodeling, and the role of endogenous electrical signals in regulating these phases has been highlighted. Recently, external electrostimulation has been shown to enhance these processes by promoting cell migration, extracellular matrix formation, and growth factor release while suppressing pro-inflammatory signals and reducing the risk of infection. Among the innovative approaches, piezoelectric and triboelectric nanogenerators have emerged as the next generation of flexible and wireless electronics designed for energy harvesting and efficiently converting mechanical energy into electrical power. In this review, we discuss recent advances in the emerging field of nanogenerators for harnessing electrical stimulation to accelerate wound healing. We elucidate the fundamental mechanisms of wound healing and relevant bioelectric physiology, as well as the principles underlying each nanogenerator technology, and review their preclinical applications. In addition, we address the prominent challenges and outline the future prospects for this emerging era of electrical wound-healing devices. [ABSTRACT FROM AUTHOR]

Biomass-derived materials have traditionally been used to generate electrical energy through the combustion of their organic components. However, within the past few years, certain common biomass compounds, especially plant-based products such as cellulose and lignin, have drawn attention in the energy field due to their wide availability, low cost, and chemical versatility. In the case of cellulose, the combination of crystalline and amorphous domains, along with the high surface area and abundance of hydroxyl groups, has allowed for its application in multiple devices to harvest energy from the environment. However, to date, there are no reviews focusing on the different approaches that have been developed to implement these sustainable materials in the generation of renewable energies and the desirable material properties for these applications. This manuscript reviews alternative ways that have been developed to exploit biomass compounds in power generation, especially cellulose and lignin. Three different types of energy harvesting are discussed: mechanical, osmotic, and thermal energy. In the case of mechanical energy, the application of plant-derived materials in piezoelectric and triboelectric generators is described. In both cases, approaches where the biomass material has an active role in power generation instead of acting as a mechanical support are reported. For osmotic energy, the performance of inverse electrodialysis systems and the use of plant-derived materials, including the chemical modifications carried out to allow for their use for energy generation, was reviewed. Finally, for thermal energy generation, the reported work on biopolymer-based devices that work using thermoelectricity has been summarised. In each case, the latest advances in the field from the materials science perspective and the reported performance were described. Hybrid approaches involving the combination of biomass materials with other components have also been considered and compared with the performance obtained using biopolymers alone. Current limitations and opportunities are, finally, discussed to offer an overview of the current landscape and indicate future directions of the field.

Facing the energy consumption of a huge number of distributed wireless Internet of Things (IoT) sensor nodes, scavenging energy from the ambient environment to power these devices is considered to be a promising method. Moreover, abundant energy sources of various types are widely distributed in the surrounding environment, which can be converted into electrical energy by micro-nano energy harvesters based on different mechanisms. In this review paper, we briefly introduce the development of different energy harvesters according to the classification of target energy sources, including microscale and nanoscale energy harvesters for vibrational energy sources, microscale energy harvesters for non-vibrational energy sources, and micro-nano energy harvesters for hybrid energy sources. Furthermore, the current advances and future prospects of the applications of micro-nano energy harvesters in event-based IoT systems and self-sustained systems are discussed.

Enhancing the output power of triboelectric nanogenerators (TENGs) requires the creation of micro or nano-features on polymeric triboelectric surfaces to increase the TENGs' effective contact area and, therefore, output power. We deploy a novel bench-top fabrication method called dynamic Scanning Probe Lithography (d-SPL) to fabricate massive arrays of uniform 1 cm long and 2.5 µm wide nano-features comprising a 600 nm deep groove (NG) and a 600 nm high triangular prism (NTP). The method creates both features simultaneously in the polymeric surface, thereby doubling the structured surface area. Six thousand pairs of NGs and NTPs were patterned on a 6 × 5 cm 2 PMMA substrate. It was then used as a mold to structure the surface of a 200 µm thick Polydimethylsiloxane (PDMS) layer. We show that the output power of the nano-structured TENG is significantly more than that of a TENG using flat PDMS films, at 12.2 mW compared to 2.2 mW, under the same operating conditions (a base acceleration amplitude of 0.8 g). [ABSTRACT FROM AUTHOR]

This study presents experimental results on the production, characterization, and applications of three-dimensionally designed piezoelectric–triboelectric hybrid nanogenerators. The hybrid nanofiber mats were manufactured using poly-(vinylidene fluoride) and thermoplastic polyurethane as the piezoelectric and triboelectric counter materials, respectively, by the simultaneous electrospinning process. Surface-engineering agents such as poly-(vinylpyrrolidone), reduced graphene oxide nanoplates (rGO NPs), and zinc oxide nanowires (ZnO NWs) were utilized in three-dimensional decoration stages. The nanofiber surfaces were roughened using the sacrifice method, followed by the application of electrospraying and hydrothermal growth techniques to decorate the nanofibers with rGO NPs and ZnO NWs, thereby enhancing the device. The resulting hybrid nanogenerators were subjected to periodic compression via an applied force, resulting in a 75.0% increase in voltage density and a 169.23% increase in current density compared to the neat hybrid nanogenerator, thanks to the surface roughening treatment. Furthermore, the decorations of rGO NPs and ZnO NWs on the nanofibers contributed to a 271.80% increase in voltage density and a 230.77% increase in current density, reaching values of 2.35 kV/m2 and 3.40 mA/m2, respectively. The nanogenerators were also tested in various applications, including energy storage, device powering, and textile sensors, to demonstrate their practicality. [ABSTRACT FROM AUTHOR]

[Display omitted] Mechanical energy harvesting transforms various forms of mechanical energy, including ocean waves, wind, and human motions, into electrical energy, providing a viable solution to address the depletion of fossil fuels and environmental problems. However, one major obstacle for the direct conversion of mechanical energy into electricity is the low frequency of the majority of mechanical energy sources (≤5 Hz), resulting in low energy conversion efficiency, output power and output current. Over recent years, a numerous innovative technologies have been reported to enable improved energy harvesting utilizing various mechanisms. This review aims to present an in-depth analysis of the research progress in low-frequency energy harvesting technologies that rely on triboelectric, electrochemical, piezoelectric, and dielectric elastomer effects. The discussion commences with an overview of the difficulties associated with low-frequency energy harvesting. The critical aspects that impact the low-frequency performance of mechanical energy harvesters, including working mechanisms, environmental factors, and device compositions, are elucidated, while the advantages and disadvantages of different mechanisms in low-frequency operation are compared and summarized. Moreover, this review expounds on the strategies that can improve the low-frequency energy harvesting performance through the modulations of material compositions, structures, and devices. It also showcases the applications of mechanical energy harvesters in energy harvesting via waves, wind, and human motions. Finally, the recommended choices of mechanical energy harvesters with different mechanisms for various applications are offered, which can assist in the design and fabrication process. [ABSTRACT FROM AUTHOR]

Triboelectric nanogenerators (TENGs) are gaining attention for energy supply because of higher demands in decentralized energy production. TENGs are known for being self-energy harvesters, converting wasted mechanical energy to useful electrical energy under an ambient environment. Advantages of TENGs include a clean energy supply, a wide range of materials selection, and an energy scavenging capability in the ambient environment. However, TENGs still suffer from their low electrical outputs compared to existing electrical supplies such as fuel cells and batteries. In bio-photovoltaic (BPV), there has been an interest in the use of microalgae, which are photosynthetic microorganisms capable of carbon capture and generating bioelectricity both day and night through electron transport chains via photosynthesis and cell respiration. To increase the current output of BPV, many have tried to immobilize living microalgal cells onto electrodes for higher mass transfers leading to higher photosynthetic rates. In this study, we have used immobilized living microalgae (Chlorella sp.) onto aluminium sheets to fabricate the TENG systems and investigate biomechanical energy harvesting. This proof of concept shows that this integration of microalgae with TENG can enhance the voltage and current output achieved by the dual operation modes of TENG. One issue raised during the tests was maintaining microalgae alive for several days, which has given opportunities for further studies in nutrient and light supplies to this innovative sustainable hybrid technology. The results confirm that the microalgae can be an excellent triboelectric layer in TENG for biomechanical energy harvesting. [ABSTRACT FROM AUTHOR]

Biomass-derived materials have traditionally been used to generate electrical energy through the combustion of their organic components. However, within the past few years, certain common biomass compounds, especially plant-based products such as cellulose and lignin, have drawn attention in the energy field due to their wide availability, low cost, and chemical versatility. In the case of cellulose, the combination of crystalline and amorphous domains, along with the high surface area and abundance of hydroxyl groups, has allowed for its application in multiple devices to harvest energy from the environment. However, to date, there are no reviews focusing on the different approaches that have been developed to implement these sustainable materials in the generation of renewable energies and the desirable material properties for these applications. This manuscript reviews alternative ways that have been developed to exploit biomass compounds in power generation, especially cellulose and lignin. Three different types of energy harvesting are discussed: mechanical, osmotic, and thermal energy. In the case of mechanical energy, the application of plant-derived materials in piezoelectric and triboelectric generators is described. In both cases, approaches where the biomass material has an active role in power generation instead of acting as a mechanical support are reported. For osmotic energy, the performance of inverse electrodialysis systems and the use of plant-derived materials, including the chemical modifications carried out to allow for their use for energy generation, was reviewed. Finally, for thermal energy generation, the reported work on biopolymer-based devices that work using thermoelectricity has been summarised. In each case, the latest advances in the field from the materials science perspective and the reported performance were described. Hybrid approaches involving the combination of biomass materials with other components have also been considered and compared with the performance obtained using biopolymers alone. Current limitations and opportunities are, finally, discussed to offer an overview of the current landscape and indicate future directions of the field. [ABSTRACT FROM AUTHOR]

Facing the energy consumption of a huge number of distributed wireless Internet of Things (IoT) sensor nodes, scavenging energy from the ambient environment to power these devices is considered to be a promising method. Moreover, abundant energy sources of various types are widely distributed in the surrounding environment, which can be converted into electrical energy by micro-nano energy harvesters based on different mechanisms. In this review paper, we briefly introduce the development of different energy harvesters according to the classification of target energy sources, including microscale and nanoscale energy harvesters for vibrational energy sources, microscale energy harvesters for non-vibrational energy sources, and micro-nano energy harvesters for hybrid energy sources. Furthermore, the current advances and future prospects of the applications of micro-nano energy harvesters in event-based IoT systems and self-sustained systems are discussed. [ABSTRACT FROM AUTHOR]