Triboelectric Generator Research Articles

Harnessing acoustic energy with liquid metal triboelectric nanogenerators: A promising approach for moving-parts-free power generation

Heat-driven acoustic engines (HDAEs) offer a promising approach to energy generation without solid moving parts. However, integrating linear alternators for acoustic-to-electric conversion introduces moving components, diminishing this advantage. To tackle this issue, we investigate using an acoustically-driven liquid–metal triboelectric generator (LM-TEG) within HDAEs for acoustic-to-electric conversion. Experiments were conducted in three settings: mechanically-driven LM-TEGs under atmospheric and pressurized gas conditions, and acoustically-driven LM-TEGs. Results from mechanically-driven LM-TEG tests show that using FEP material, increasing LM-TEG contact area, stacking TEGs in parallel, and using pressurized gas enhance performance. Acoustically-driven LM-TEG experiments demonstrate significant improvements with pressurized nitrogen, achieving a short-circuit current approximately 4.5 times higher than with helium at equivalent pressures. Notably, charge and power densities reached 388 μC/m2 and 1.7 W/m2, respectively, surpassing typical values from conventional TEGs. Importantly, these results were obtained with a complete, fully integrated acoustically driven LM-TEG system. This study represents the first investigation in the literature of acoustically driven LM-TEGs, offering a distinct power generation system with no solid moving parts. The findings validate the feasibility of integrating LM-TEGs with HDAEs and suggest their potential for large-scale power generation, moving beyond the small-scale applications that have dominated prior TEG research.

Multifunctional Triboelectric Metamaterials with Unidirectional Charge Transfer Channels for Linear Mechanical Motion Energy Harvesting

AbstractConventional triboelectric generators (TEGs) have been developed to mainly harvest the energy of linear mechanical motions and convert it usually into oscillating or pulsive, but not sustainable, electrical outputs. In this study, unidirectional charge transfer mechanisms are introduced to develop a triboelectric mechanical metamaterial (TMM) with sustainable electrical outputs. Density functional theory and experimental analyses demonstrate three minimum necessary components of TMMs fabricated by only two triboelectric materials (i.e., copper and PTFE) to generate sustainable electrical outputs. Under a wide range of compression‐tension strain of ±50%, the maximum open‐circuit voltage, short‐circuit current, and volumetric power density are 3860 V, 8 µA, and 365.3 kW m−3, respectively. Different from most conventional cellular solids, the mechanical energy dissipation of the TMMs increases quadratically with the unit cell number. High volumetric electromechanical efficiency is achieved when the unit cell is miniaturized. In addition to energy harvesting and mechanical energy dissipation, TMMs can sense the displacement by counting the number of distinctive peaks in the short‐circuit charge transfer or reaction force versus time curves. The extreme electromechanical functionalities of the TMMs facilitate their applications in intelligent suspension systems, miniaturized green power sources, and self‐sensing energy harvesters.

Unique Triboelectric Nanogenerator Using Carbon Nanotube Composite Papers

A unique triboelectric nanogenerator (TENG) using carbon nanotube (CNT) composite papers is proposed in this work. CNT composite papers can be fabricated easily using a method based on the production of Japanese washi paper. To obtain and evaluate the proposed TENGs, several types of CNT composite papers and aluminum plates were prepared. As the CNT composite paper contained many paper fibers, it was expected to be negatively charged, and the aluminum plate was expected to be positively charged across the triboelectric series. Through various experiments, it was confirmed that CNT composite papers could be used as TENGs. In addition, it was found that when a CNT composite paper was used, it contributed to triboelectricity generation, and the contained CNTs efficiently transferred the generated charge to the electrodes. Furthermore, output voltages approaching a maximum RMS value of 300 mV could be obtained. The results of this study will aid in the practical application of paper-based TENGs in the near future.

Water-Triboelectrification-Complemented Moisture Electric Generator.

Energy harvesting from ubiquitous natural water vapor based on moisture electric generator (MEG) technology holds great potential to power portable electronics, the Internet of Things, and wireless transmission. However, most devices still encounter challenges of low output, and a single MEG complemented with another form of energy harvesting for achieving high power has seldom been demonstrated. Herein, we report a flexible and efficient hybrid generator capable of harvesting moisture and tribo energies simultaneously, both from the source of water droplets. The moisture electric and triboelectric layers are based on a water-absorbent citric acid (CA)-mediated polyglutamic acid (PGA) hydrogel and porous electret expanded polytetrafluoroethylene (E-PTFE), respectively. Such a waterproof E-PTFE film not only enables efficient triboelectrification with water droplets' contact but also facilitates water vapor to be transferred into the hydrogel layer for moisture electricity generation. A single hybrid generator under water droplets' impact delivers a DC voltage of 0.55 V and a peak current density of 120 μA cm-2 from the MEG, together with a simultaneous AC output voltage of 300 V and a current of 400 μA from the complementary water-based triboelectric generator (TEG) side. Such a hybrid generator can work even under harsh wild environments with 5 °C cold and saltwater impacts. Significantly, an optical alarm and wireless communication system for wild, complex, and emergency scenarios is demonstrated with power from the hybrid generators. This work expands the applications of water-based electricity generation technologies and provides insight into harvesting multiple potential energies in the natural environment with high output.

Harvesting multidirectional wind energy based on flow-induced vibration triboelectric nanogenerator with directional tuning mechanism

Wind-induced vibration (WIV), as low-velocity wind energy utilization technology in agricultural environment, has significant advantages. Nevertheless, there is a mismatch between the variability of wind direction and the work mode of triboelectric nanogenerator (TENG), which leads to a sharp decline in the performance of triboelectric power generation. This work proposes a TENG based on multidirectional WIV (TENG-WIV), which mainly contains triboelectric power generation unit, guide-wing and triboelectric direction sensor. By introducing the directional tuning mechanism based on guide-wing, the TENG-WIV aims to break the constraints of single wind direction response and effectively respond to the wind direction within 360° range, thereby realizing multidirectional wind energy harvesting and sensor power supply. The empirical findings indicate that the output voltage and current of triboelectric power generation unit are in the ranges of 62–241 V and 0.25–1.21 μA, respectively, at the wind velocities of 1.23–5.13 m/s. At a wind velocity of 3.18 m/s, the unit achieves an out-power peak of 0.09 mW. Furthermore, the triboelectric direction sensor can respond to changes in 8 directions and has wind direction monitoring potentiality. The directional tuning mechanism endows flow-induced vibration energy harvesters with an all-around multidirectional sensitivity.

Biocompatible triboelectric energy generators (BT-TENGs) for energy harvesting and healthcare applications.

Electronic waste (e-waste) has become a significant environmental and societal challenge, necessitating the development of sustainable alternatives. Biocompatible and biodegradable electronic devices offer a promising solution to mitigate e-waste and provide viable alternatives for various applications, including triboelectric nanogenerators (TENGs). This review provides a comprehensive overview of recent advancements in biocompatible, biodegradable, and implantable TENGs, emphasizing their potential as energy scavengers for healthcare devices. The review delves into the fabrication processes of self-powered TENGs using natural biopolymers, highlighting their biodegradability and compatibility with biological tissues. It further explores the biomedical applications of ultrasound-based TENGs, including their roles in wound healing and energy generation. Notably, the review presents the novel application of TENGs for vagus nerve stimulation, demonstrating their potential in neurotherapeutic interventions. Key findings include the identification of optimal biopolymer materials for TENG fabrication, the effectiveness of TENGs in energy harvesting from physiological movements, and the potential of these devices in regenerative medicine. Finally, the review discusses the challenges in scaling up the production of implantable TENGs from biomaterials, addressing issues such as mechanical stability, long-term biocompatibility, and integration with existing medical devices, outlining future research opportunities to enhance their performance and broaden their applications in the biomedical field.

Peeling-induced interfacial roughness and charging for enhanced triboelectric power generation

To date, there have been a lot of efforts to enhance the conversion efficiency of triboelectric nanogenerators (TENGs) via physical and chemical modifications of the polymer surface. Herein, we report that a facile peeling of polymer from a substrate can enhance the triboelectric power output. The peeling of spin-coated polydimethylsiloxane (PDMS) from glass and polytetrafluoroethylene (PTFE) substrates has revealed a considerable increase in interfacial roughness and lateral friction. Surface-sensitive X-ray photoemission spectroscopy and non-contact current measurements have also revealed the transfer of counter-material and interfacial charging. The surface roughness of peeled PDMS is significant for the PTFE substrate, while the surface charge is significant for the glass substrate. The triboelectric output power density for peeled PDMS from the substrate is similar, 10.3 µW/cm2, but significantly larger than that for as-grown PDMS (2.2 µW/cm2). The peeling strength of PDMS significantly increases for glass compared to PTFE after the oxygen plasma treatment of substrates. The triboelectric charge of peeled PDMS from a plasma-treated glass substrate is almost 1.3 times larger than that from a PTFE substrate. This work implies that peeling polymer from a rough substrate with a large adhesion force would be a facile and effective way to increase the triboelectric power output, without any delicate surface treatments.

Extending Dynamic Blind Interaction: Microgap Discharge-Induced Flexible Virtual Electrotactile Braille.

Braille is an essential implement for the blind to communicate with outside, but traditional Braille is limited to a paper-based format that cannot directly provide real-time word information. In this work, a flexible virtual electrotactile Braille is proposed that can benefit the blind from blocked interaction. The Braille interface, S-shaped wires and a sphere electrode with a textile fingerstall integrated by silicone, offers flexibility and simultaneously generates the microgap through textile cracks, which achieves virtual electrotactile sensation by electrostatic discharge. Powered by a high-voltage triboelectric generator of 10.2 kV designed through the charge accumulation and induction strategy, the electrotactile stimulation is realized with a microgap discharge of only 40 μA current induced on the finger. A dynamic electrotactile Braille is finally assembled, controlled by a programmable relay array. The strategies of short circuit and voice reminder are employed, so that the recognition of dynamic Braille letters is realized with spatiotemporal electrotactile stimulation and high recognition accuracy. This virtual electrotactile Braille brings convenience for the blind to access the information world and illustrates its applications to promote virtual electrotactility in this special community.

Study of wind energy harvesting based on rolling bearing type triboelectric nanogenerator

This research developed a novel rolling bearing type triboelectric generator (RB-TENG) designed to efficiently harvest wind energy across a broad spectrum of wind speeds. This generator consists of a column stator shell made of rigid transparent resin. The inside of the stator is open with a circular track affixed with four pairs of copper electrodes, which rub against PTFE balls, using the independent layer operating mode of the triboelectric nanogenerator, due to the use of rolling friction pairs with the collection of a wide range of wind speeds, as low as 2.5 m/s wind speed can be collected. RB-TENG uses rolling friction instead of sliding to extend its service life. The experimental results show that within the wind speed range of 2.5 m/s to 8 m/s, the output performance of RB-TENG increases randomly with the increase of wind speed, and the numerical growth is not very significant after the wind speed of 6 m/s. The effective power density measured at a wind speed of 8 m/s was 5.07 mW/m2. Furthermore, experiments validate the RB-TENG's capability to power small appliances and its potential applicability in sea farms. It provides a viable solution to reducing reliance on fossil fuels and offers a multi-purpose strategy based on wind energy.

What Puts the "Tribo" in Triboelectricity?

An enduring question in science has been why sliding plays a major role in the triboelectric generation of static electricity-the "tribo" in triboelectricity. We provide here a general explanation which is rooted in established science. When sliding is taking place, there is symmetry breaking due to elastic shear, so the front of the sliding body experiences different elastic strains from the back. Consequently the polarization and associated charges at the front and back are not the same, and the difference between the two leads to current flow similar to the difference in air pressure above and below a plane's wing leading to lift. Specific calculations are provided which show good agreement with prior experimental measurements of size and shape dependencies, and reasonable quantitative agreement with experimental current measurements.

Tactile sensory synapse based on organic electrochemical transistors with ionogel triboelectric layer

Recent advancements in artificial tactile sensory systems have significantly improved their ability to replicate the sensory functions of biological systems by integrating various sensory and synaptic components, yet these configurations often lack the efficiency and seamless integration seen in nature. To address these limitations, we introduce a monolithic artificial mechanoreceptor that combines an organic electrochemical transistor with an ionogel (IG), serving as both a mechano-responsive triboelectric sensing layer and a gate electrolyte. Triboelectrification upon mechanical stimulation using different materials produces an output voltage of the triboelectric generator which drives the movement of ions within the tribo-negative IG based on 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ionic liquid and poly(vinylidene fluoride-co-hexafluoropropylene), modulating de-doping of the poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) channel. This enhances synaptic functionalities such as spike number-dependent plasticity (SNDP) and spike duration-dependent plasticity (SDDP) during mechanical stimulation, allowing the device to mimic biological mechanoreceptors by sensing and converting external mechanical signals, including the number, force, and duration of touches, into synaptic plasticity. Furthermore, the device shows potential for material recognition using machine learning techniques, marking a significant advancement towards efficient artificial tactile systems.

Self-powered wireless sensor node enabled by ultra-high-output swinging hybrid generator toward real-time and in-situ marine meteorological observations

With the intensification of global ocean exploration, there is an increasing need for extensive and dispersed wireless sensor networks (WSNs) to meet the requirements of real-time, in-situ, and high-spatial-temporal-density marine meteorological observations. Nevertheless, providing a reliable power source and ensuring the ongoing maintenance of these WSNs pose significant challenges. Here, an innovative self-powered wireless sensor node is developed to address these challenges, featuring an ultra-high-output triboelectric-electromagnetic hybrid generator (T-EHG) with a swinging mechanism. The T-EHG, which combines triboelectric (TENG) and electromagnetic (EMG) generation, assisted by a universal power management system (UPMS), efficiently converts wave energy into a consistent voltage output between 1.5 V to 3.3 V. Additionally, the self-powered WSNs integrated with T-EHG, UPMS circuits, meteorological sensors, and microcontroller units (MCUs) with LoRa wireless transmission functionality are capable of executing data collection and transmission operations every 10 s under simulated wave conditions. These systems can achieve a maximum wireless transmission range of 1.5 km. Notably, a marine meteorological monitoring system utilizes these autonomous sensor nodes, along with base stations, cloud servers, and terminal devices to effectively implement real-time, on-site measurements of temperature, humidity, and air pressure within the monitored zone. This research underscores the substantial practical utility and extensive application prospects of these advanced self-powered WSNs for marine meteorological surveillance.

Cooperation mechanism between the vacuum levels and interface dipole energy of triboelectric materials for real-time vibration recognition

Triboelectric Nanogenerator (TENG) device, acting as sensors of energy harvesting and material identification, are attracting intensive attention. Nevertheless, vibration wave recognition cannot be achieved by the developed devices owing to device structure and working mechanism limitations. Here, a cooperation mechanism between the vacuum level and interface dipole energy of triboelectric materials is proposed to explore triboelectric charge generation and migration. Hence, metallized cottons of high specific surface area encapsulated by polydimethylsiloxane (PDMS) of low elastic modulus are developed as TENG-based sensors to realize vibration recognition. The results indicate electrons flow from PDMS to metallized cotton with the generation of an extremely thin interfacial dipole barrier layer because the vacuum level of metallized cotton is higher than that of PDMS, resulting in the accumulation of triboelectric charges on the PDMS surface under vibration, further leading to generating distinct triboelectric signals that can be simply differentiated using signal amplitude or peak shape with 98.3 % recognition accuracy for vibration waveform. Besides, combined with the deep machine learning and triboelectric effect, a vibration perception system integrated with a TENG-based sensor, data processing and display modules is also developed for real-time vibration monitoring. This work contributes to further clarifying the theoretical mechanisms of triboelectric charge excitation under vibration.

Sustainable energy potentials of textile-based triboelectric generators through simulation of real usage conditions

Sustainable energy potentials of textile-based triboelectric generators through simulation of real usage conditions

Physical and Chemical Surface Modification of Recycled Polystyrene Films for Improved Triboelectric Properties

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.

Triboelectric Nanogenerators: State of the Art.

The triboelectric nanogenerator (TENG), as a novel energy harvesting technology, has garnered widespread attention. As a relatively young field in nanogenerator research, investigations into various aspects of the TENG are still ongoing. This review summarizes the development and dissemination of the fundamental principles of triboelectricity generation. It outlines the evolution of triboelectricity principles, ranging from the fabrication of the first TENG to the selection of triboelectric materials and the confirmation of the electron cloud overlapping model. Furthermore, recent advancements in TENG application scenarios are discussed from four perspectives, along with the research progress in performance optimization through three primary approaches, highlighting their respective strengths and limitations. Finally, the paper addresses the major challenges hindering the practical application and widespread adoption of TENGs, while also providing insights into future developments. With continued research on the TENG, it is expected that these challenges can be overcome, paving the way for its extensive utilization in various real-world scenarios.

Nano-Enhanced Triboelectric Generators: Investigating Additive Effects on Output Voltage

Nano-Enhanced Triboelectric Generators: Investigating Additive Effects on Output Voltage

Batch-to-Batch Variation in Laser-Inscribed Graphene (LIG) Electrodes for Electrochemical Sensing.

Laser-inscribed graphene (LIG) is an emerging material for micro-electronic applications and is being used to develop supercapacitors, soft actuators, triboelectric generators, and sensors. The fabrication technique is simple, yet the batch-to-batch variation of LIG quality is not well documented in the literature. In this study, we conduct experiments to characterize batch-to-batch variation in the manufacturing of LIG electrodes for applications in electrochemical sensing. Numerous batches of 36 LIG electrodes were synthesized using a CO2 laser system on polyimide film. The LIG material was characterized using goniometry, stereomicroscopy, open circuit potentiometry, and cyclic voltammetry. Hydrophobicity and electrochemical screening (cyclic voltammetry) indicate that LIG electrode batch-to-batch variation is less than 5% when using a commercial reference and counter electrode. Metallization of LIG led to a significant increase in peak current and specific capacitance (area between anodic/cathodic curve). However, batch-to-batch variation increased to approximately 30%. Two different platinum electrodeposition techniques were studied, including galvanostatic and frequency-modulated electrodeposition. The study shows that formation of metallized LIG electrodes with high specific capacitance and peak current may come at the expense of high batch variability. This design tradeoff has not been discussed in the literature and is an important consideration if scaling sensor designs for mass use is desired. This study provides important insight into the variation of LIG material properties for scalable development of LIG sensors. Additional studies are needed to understand the underlying mechanism(s) of this variability so that strategies to improve the repeatability may be developed for improving quality control. The dataset from this study is available via an open access repository.

Portable Multi-Layer Capsule-Shaped Triboelectric Generator for Human Motion Energy Harvesting.

This paper introduces a novel portable multi-layer capsule-shaped triboelectric generator (CP-TEG), aimed at optimizing the performance of triboelectric generator technology in terms of miniaturization, modularity, and efficient energy collection. The CP-TEG utilizes a unique multi-layer, stacked structure and an elliptical cylindrical design to increase the effective frictional area and enhance power generation efficiency. Its portable design allows for flexible application in various environments and scenarios. Experimental results demonstrate that the CP-TEG can maintain stable and efficient electrical output under various motion amplitudes and frequencies, and it shows good adaptability to the direction of motion excitation. With a motion amplitude of 7 cm and a frequency of 1.94 Hz, the CP-TEG can charge a 220 μF capacitor to 1.3 V within 100 s. The power generation unit's output voltage and current are more than three times higher than that of traditional single-layer contact-separation mode triboelectric devices. Particularly, its performance in harvesting energy from human motion underscores its effectiveness as a renewable energy solution for wearable devices. Through its innovative structural design and optimized working mechanism, the CP-TEG demonstrates excellent energy collection efficiency and application potential, offering new options for sustainable energy solutions and development.

Wearable, Machine Washable, Breathable Polyethylenimine/Sodium Alginate Layer-by-Layer-Coated Cotton-Based Multifunctional Triboelectric Nanogenerators.

Cotton-based textiles are ubiquitous in daily life and are prime candidates for application in wearable triboelectric nanogenerators. However, pristine cotton is vulnerable to bacterial attack, lacks antioxidant and ultraviolet (UV)-protective abilities, and shows lower triboelectric charge generation against tribonegative materials because it is present in the neutral region of the triboelectric series. To overcome such drawbacks, herein, a facile layer-by-layer method is proposed, involving the deposition of alternate layers of polyethylenimine (PEI) and sodium alginate (SA) on cotton. Such modified fabric remains breathable and flexible, retains its comfort properties, and simultaneously shows multifunctionalities and improved triboelectric output, which are retained even after 50 home laundering cycles. Also, the modified fabric becomes more tribopositive than nylon, silk, and wool. A triboelectric nanogenerator consisting of modified cotton and polyester fabric is proposed that shows a maximum power density of 338 mW/m2. An open-circuit voltage of ∼97.3 V and a short-circuit current of ∼4.59 μA are obtained under 20 N force and 1 Hz tapping frequency. Further, the modified cotton exhibits excellent antibacterial, antioxidant, and UV-protective properties because of the incorporation of PEI, and its moisture management properties are retained due to the presence of sodium alginate in the layer. This study provides a simple yet effective approach to obtaining durable multifunctionalities and improved triboelectric performance in cotton substrates.