Triboelectric Charging Research Articles

Laboratory investigations of triboelectric charging of dust by rover wheels

The dusty plasma environments of airless bodies present challenges for both exploration and science missions to their surfaces. Objects moving on the surface, such as rover wheels, transfer charges onto regolith dust due to the triboelectric effect. The charged dust particles can readily stick to spacesuits as well as the optical, electronic, and mechanical components of equipment and instruments, causing their degradation. This effect is more pronounced in permanently shadowed regions (PSRs) of the Moon, where the charge dissipation rate is low due to a lack of ambient plasma. Here we report the first results of an experimental investigation of the tribocharging effect between dust and rover wheels. Various wheel surface materials along the triboelectric series are selected. The effects of varying wheel speeds and dust types are explored. Results indicate that charge distributions conform to the triboelectric properties of the dust and material it comes into contact with. High charges of up to ∼2 pC are measured on dust grains ∼100 μm in diameter, which is equivalent to a surface potential of few hundred volts. Results also suggest that higher wheel speeds may result in more dust-dust interactions, changing the charging behavior of the dust grains. These findings indicate a need for future studies to better understand tribocharging in various exploration scenarios in order to design effective dust mitigation strategies and methods.

Customizable non-charging material for eliminating electrostatic charge of particles at source

Contact electrification causes the electrostatic adhesion of particles onto surfaces. This causes a vast range of severe problems. In industry, fouling causes blockages of processes (e.g., vessels and pipes) and prevents Process Analytical Technology (PAT) probes from functioning. In research laboratories, adhesion causes expensive powders to be routinely lost during normal operations. To address these wide-ranging problems, this study describes a non-conductive polymeric material that resists triboelectric charging against powders (e.g., pharmaceutical and food). The material is a novel blend of two approved food- and pharmaceutical-grade polymers at a specific proportion. One polymer tends to charge positively (i.e., polyvinyl acetate; PVAc), whereas the other tends to charge negatively (i.e., polyvinylidene fluoride; PVDF), against the targeted powder. The non-charging polymer blend of PVAc and PVDF is successfully designed, translated, and deployed into industrially relevant situations. The polymer blend prevented milk powder and ethylcellulose powder from fouling the stainless-steel surface of a vessel in the food industry (e.g., for blending). It prevented aspirin powder from fouling an NIR probe used for accurate continuous monitoring of moisture during the drying process in a standard pharmaceutical industry glass filter dryer (GFD) for a long time of > 210 min. The original probe stopped functioning within 5 min. It prevented the adhesion of different types of expensive protein and enzyme powders onto tubes (e.g., for storage and transfer) commonly used in research laboratories. Therefore, this non-charging polymer blend is a universal solution for preventing particle adhesion and fouling for different types of processes, industries (e.g., food or pharmaceutical manufacturing), and powders.

Creating Ultrahigh and Long‐Persistent Triboelectric Charge Density on Weak Polar Polymer via Quenching Polarization

AbstractTo achieve high charge density for the triboelectric polymer is a crucial task for fabricating triboelectric nanogenerators (TENGs). This work has developed a quenching polarization (QP) method to create ultrahigh and long‐persistent triboelectric charge on the triboelectric polymer with weak dipole polarity. The Ethylene chlorotrifluoroethylene copolymer (ECTFE) film can reach a charge density of 391 µC m−2 in the vertical contact mode by using this QP treatment, which is 200% higher than the result achieved by the most widely used method of corona polarization. The mechanism of the improvement through QP on the triboelectric properties is studied on the basis of the polarization induced grain refinement and interfacial trapping. The QP‐treated ECTFE can maintain ultra‐high charge density for both solid‐solid and solid‐liquid TENG. More interestingly, the charge induced by QP treatment is so persistent that it produces a recoverable discharging phenomenon for solid‐liquid TENG, which has never been observed before. This QP method provides a different approach for fabricating high‐performance triboelectric materials, while the QP‐induced changes in crystallization and tribo‐charge density can help to complete the physical understanding of the electrification mechanism of triboelectric polymer.

A vibratory-type triboelectric charging device design of experiments based modelling for controllable and uncontrollable parameters effect study

The aim of the present paper is to study the effect of the controllable and uncontrollable parameters on the charge per mass ratio of the triboelectrical vibratory charging device. The controllable parameters are related to the device, which are the feed rate, the particle velocity, and the length of the vibrating plate. The uncontrollable ones are those related to the intrinsic properties of the materials involved in the triboelectrical charging. The design of experiments approach, leading to model the system, is used to determine the optimal operating parameters of the vibratory feeding of the mechanism triboelectric charging for plastic pellets. A series of tribocharging experiments are conducted on acrylonitrile-butadiene-styrene (ABS) and high-impact polystyrene (HIPS) granules, with a particle size of 1–2 mm, to figure out the behavior of materials representing uncontrollable parameters and the limit range of controllable parameters. The obtained results, based on the design of experiments method, show the influence of control and correlation between the controllable parameters to get a satisfied charge per mass ratio, which is also strongly influenced by the uncontrollable parameters.

Dynamic behavior of tunneling triboelectric charges in two-dimensional materials

Dynamic behavior of tunneling triboelectric charges in two-dimensional materials

Impact of photovoltaic effect on performance enhancement of triboelectric nanogenerator for energy harvesting applications

The photo-induced triboelectric nanogenerator (PTENG) has been explored as new generation energy technology, which is enabled by coupling triboelectric and photo-induced charge carriers. PTENG shows a dual work mechanism that is attributed to the synergetic outcome of the photovoltaic and triboelectric effects. This study aims to provide a new strategy for triboelectric nanogenerator devices to achieve high output performance for various smart electronic device applications. Aluminum and n-type silicon were chosen as two different materials for triboelectric measurements. Different techniques were adopted to obtain triboelectric output parameters through the in-house developed triboelectric setup. AFM and Kelvin probe force microscopy imaging techniques were employed to obtain surface roughness and to measure the change in surface potential under the illumination of red (630 nm) laser light. A significant improvement in surface potential of around 40 mV was observed under laser illumination. Triboelectric characterization has been performed to obtain open circuit voltage (VOC) and short circuit current (ISC) with and without light illumination at different speeds of the motor. VOC and Isc were found to be 0.8 V and 2.2 nA, respectively, at 50 rpm speed without any illumination, which was further enhanced to 1.8 V and 5.5 nA, respectively, under the influence of laser light illumination. An increase in the motor speed to 100 rpm results in higher VOC (2.4 V) and higher ISC (3.4 nA) as compared to 50 rpm at no illuminating condition. However, it enhances to 3.4 V and 6.0 nA in illuminating conditions. This is attributed to the generation of charge carrier due to triboelectrification, which is further enhanced because of the photovoltaic effect wherein the generation of electron-hole pair occurs due to the shining of light on the side of semiconductors. These synergetic effects have tremendous potential in sustainable energy harvesting.

Three-dimensional graphene foam based triboelectric nanogenerators for energy systems and autonomous sensors

In this work we investigate the potential of three-dimensional graphene (3DG) foam as an active layer in triboelectric nanogenerators (TENGs) and as an energy harvesting power source for autonomous sensors. A series of comprehensive measurements have been carried out to test the output characteristics of 3DG-TENG under cyclic mechanical stimulus, capable of operating TENG in contact-separation mode at different frequencies, gap distances between electrodes, and applied pressures. The triboelectric response of 3DG-TENG (with an effective surface of 16 cm2) showed maximum open-circuit voltage (Voc) and short-circuit current (Isc) of 400 V and 105.7 μA respectively when stimulated at 3 Hz (contact-separation frequency) and 70 mm (optimum gap distance). Under the same conditions, a maximum output power (Pout) of around 10.37 W/m2 is produced using an external load resistance of 40 MΩ; this is an order of magnitude lower resistance than that needed with other graphene based TENG variants. 3DG-TENG exhibited great stability in the output characteristics with 15,000 cyclic mechanical stimuli and a retention percentage in Pout above 95%. This is a significant improvement with respect to other carbon based TENG`s, which show enhanced deterioration of TENG performance due to material transfer between electrodes and plastic deformation of triboelectric materials. Simulations of TENG Voc using distance dependent model determined high triboelectric charge densities in the range of mC/m2. Here, we also demonstrate the potential of 3DG-TENG as an energy supply for energy storage devices, and as an active layer in an autonomous pressure sensing platform for anonymous room occupancy monitoring in smart buildings.

Triboelectric nanogenerator of 3D printed textile structure for energy harvesting application

Energy-harvesting technology, which converts discarded energy from nature into electric energy, has recently attracted attention as a solution to environmental problems, such as the exhaustion of fossil fuels, climate change, and environmental pollution. A triboelectric nanogenerator (TENG) convert mechanical shaking into electrical signals through triboelectric charging and electrostatic induction in an internal circuit, collecting wasted mechanical kinetic energy from the body, such as walking and breathing. In this study, models of a textile structure and 3D printing were used to verify the applicability of TENG of 3D Printing textile structures by outputting textile structures using 3D Printing, textile structure was modeled and 3D printed to check the TENG applicability of the 3D Printing style structure by outputting the textile structure using 3D Printing, and freestanding mode TENG was manufactured using the fabric structure output as a tribo-layer to evaluate the maximum power voltage under various conditions. The results of this study evaluated the maximum output voltage under various conditions. The thickness and load were also increased. The factors that influence the selection of materials can be identified.

Quasi-electrostatic three-dimensional charge model for contact-separation triboelectric nanogenerator

Triboelectric nanogenerators (TENGs) are at the forefront of energy harvesting and self-powered sensors, while further improvements in TENGs’ development and utilization essentially depend on the theoretical models. To understand the intrinsic mechanism of TENGs, a formal physical framework of TENGs was introduced based on Maxwell’s equations. Triboelectric charges would be produced on the dielectric layer surface after contact triboelectrification. As concerned about any transient, the electric field originating from the arbitrary fixed position over the finite charged plane would not change, constituting the electrostatic field. Since TENGs maintain low-frequency movement, they enter a quasi-electrostatic state. Under this state, the electric field would change along with the distance from the charged plane. Herein, a quasi-electrostatic three-dimensional (QETD) charge model was constructed to refine the theoretical modeling of TENGs. Finite element modeling (FEM) simulations were first provided to reveal the distribution of polarization vector (Pz), electric potential (φ), electric field (Ez) and electric displacement (Dz). Furthermore, an optimized theoretical framework for contact-separation TENGs was established, and it was validated by different driving and structural variables. Besides, the intrinsic displacement current of TENGs was linked with the conduction current to deduce the output capability. Compared with previous works, this QETD model shows the most consistent trend with experimental results, providing accurate predicts for distinct TENGs’ performance.

Triboelectric charge modulation to understand the electrification process in nanogenerators combined with an efficient power management system for IoT applications

Mechanical energy harvesting from ambient environment has been considered one of the promising technologies for developing autonomous self-powering units, sensors, and various other electronic applications. Triboelectric nanogenerators (TENGs) are one of the recent technologies gaining tremendous interest because of their ability to efficiently harvest ambient energy and convert it into electricity. The phenomenon of the triboelectrification effect in TENGs is not fully understood, along with extracting a maximum electrical output. Herein, we studied the electrification process between two triboelectric films by modulating their charge polarity. The charge polarity in the triboelectric film was modulated without any surface chemical functionalization. A TENG was fabricated to experimentally study the electrification process. Initially, the accepting/donating electrons of a triboelectric film were modulated using fluorine and oxygen atoms contained in polymers and operated against an oppositely charged triboelectric film. After optimizing the electrical output and conducting various stability investigations, the electrical output from the TENG was enhanced. Ultra-low power management integrated circuit (PMIC) implemented in a 180 nm high-voltage BCD (Bipolar CMOS DMOS) process was used. While matching the effective impedance of the TENGs, the PMIC achieves a total energy transfer efficiency of 81.5% utilizing a relatively low input power of 6.5 µW, showing state-of-the-art performance.

Enabling triboelectric charging as a powder charging method for electrophotographic powder application in laser-based powder bed fusion of polymers by triboelectric charge control

Enabling triboelectric charging as a powder charging method for electrophotographic powder application in laser-based powder bed fusion of polymers by triboelectric charge control

Experimental investigation of an optimised tribocharger design for space resource utilisation

Triboelectric charging and free-fall separation are attractive technologies for lunar mineral beneficiation. Here, an optimised tribocharger design was built and evaluated under terrestrial conditions. The charging behaviour of pure silica and ilmenite were tested using the optimised design, as were mixtures of silica and ilmenite, and samples of lunar regolith simulant JSC-1. Pure silica and ilmenite acquired negative and positive charge, respectively, through contact with the tribocharger. The tribocharger affected significantly the movement of the pure minerals in the electrostatic field. Results from the binary mixtures indicate that ilmenite recovery is independent of initial ilmenite concentration, and can be predicted from the mass distribution of pure ilmenite samples. For JSC-1, the tribocharger was found to increase the density of the material in certain collectors, indicating an upgrading of denser constituents. The optimised tribocharger design has a significant effect on the charging and separation performance.

Strongly enhanced charge density via gradient nano-doping for high performance elastic-material-based triboelectric nanogenerators

Elastic-material-based triboelectric nanogenerators (EMB-TENGs) are most effective to harvest random (low frequency, low amplitude) and distributed mechanical energy. However, the low output of EMB-TENGs caused by drastic charge attenuation and low sensitivity limits its applications. Here, we propose a gradient nano-doping strategy to boost the charge density and sensitivity of triboelectric sponge materials via the gradient electrical field caused by the inhomogeneous concentration field of polytetrafluoroethylene nanoparticles. The triboelectric charge density (537 μC·m−3) and the peak power density (732.6 mW·m−3) is increased by 1.2 times and 1.8 times. A sensitivity of 1.851 kPa−1 is successfully realized at 50% compressive strain. From this, a self-powered smart boxing bag with functions of both the force analysis and real-time counting statistic was developed at the large strain. This work presents a new method for design and development of triboelectric materials, as well as expanding the functionalities and applications of self-powered system combining with the EMB-TENGs.

Improved perovskite triboelectric nanogenerators by effective defect passivation and interface modulation

Perovskite-based triboelectric nanogenerators (TENGs) have obtained wide attention and investigation due to their excellent dielectric and electrical properties, as well as the diversity of perovskite materials. In this work, phenethyl ammonium iodide (PEAI) was applied to tailor the interface of MAPbI3 films, to form a 2D/3D heterojunction, and to passivate defects of films. The TENGs after PEAI passivation achieved significant improvement in voltage and current density with an increase in the output voltage from 33.3 to 40.1 V, and the current density was improved from 9.1 to 10.1 mA/m2. The improved output properties might be attributed to changes in the triboelectric charge density, carrier mobility, reduced interfacial combination by effective defect passivation, and favorable charge transporting by constructing 2D/3D heterojunctions for the effect of the built-in electric field. This work demonstrates that interfacial modification is one of the feasible methods for improving the performance of TENGs and supplies further possibilities for high-performance perovskite-based TENGs.

Boosting output performance of triboelectric nanogenerator based on BaTiO3:La embedded nanofiber membrane for energy harvesting and wireless power transmission

To boost output charge density for achieving high-performance triboelectric nanogenerator (TENG), increasing dielectric constant of triboelectric materials is considered as an important strategy. Herein, a high-performance TENG is fabricated based on BaTiO3:La-embedded poly (vinylidene fluoride-trifluoro-ethylene) (PVDF-TrFE) nanofiber membrane (NM) (BLPT-NM) for energy harvesting and wireless power transmission. The obtained BLPT-NM shows an enhanced electronegativity and a significant increase in dielectric constant (38.8 at 10 kHz) through facile electrospinning and proper concentration optimization of BaTiO3:La. The fabricated single-electrode-mode TENG based on BLPT-NM (3 × 3 cm2) demonstrates excellent output performance with power density of 2.52 W m–2 (ƒ=1.5 Hz) and triboelectric charge density of 87.3 μC m−2, which are significantly increased by more than 11- and 3-fold, respectively, in comparison with those of the TENG based on pristine PVDF-TrFE-NM. More importantly, a wireless power transmission for transmitting electrical signals is successfully achieved via Maxwell’s displacement current generated by the BLPT-NM based TENG after directly harvesting ambient biomechanical energy. Furthermore, the wirelessly received signals can trigger the operation of some electronics in real time. This work demonstrates an effective strategy for boosting the output performance of TENG and paves a new route to further promote the development of wireless power transmission technologies.

Laminating Structure for Interlayer Corona Discharge Treatment Toward Ion-Based Nanogenerators.

A corona discharge treatment (CDT) is utilized to maximize the performance of triboelectric nanogenerators (TENGs) by injecting extra electrons into the negative tribomaterials. Increased performance of CDT TENGs, however, exhibits rapid degradation due to the electron dissipation by air moisture or thermal emission. To overcome such drawbacks and circumvent such dissipation, the source of charges should be replaced with ionic charges. This study reports a Ag nanowires (NWs)-embedded laminating structure (AeLS) with a unique fabrication procedure for ionic charge injection by CDT. The injection of ions is achieved by interlayer-CDT (i-CDT), in which positive charges are dissipated by Ag NWs, and the opposite negative ions can remain on the outmost surface. The AeLS TENGs with i-CDT exhibit high performance, long-term stability, and durability. It shows voltage, current, and maximum power outputs of 380V, 15µA, and 827mW m-2 , respectively. As a practical demonstration, rotational TENG integrated with a direct discharge system is realized, and its current and voltage reach 7.4mA and 7800V, respectively. This work can pave the way for the design of ion-based TENGs with high performance and long-lasting retention of triboelectric charges.

Triboelectric polymer with excellent enhanced electrical output performance over a wide temperature range

Due to thermionic emission of triboelectric charge and degradation of mechanical stability of polymer tribomaterials (PTMs), PTMs based TENG (PTM-TENG) cannot maintain efficient electrical output and operate stably at high temperatures. Herein, a series of fatty acid doped PVDF-HFP (PH-FA) PTMs are fabricated. The introduction of FA lubricants dramatically increases the β-phase relative fraction, dielectric constant and surface charge potential of PTMs. Therefore, the PH-SA (stearic acid) based TENG shows improved electrical output over a wide temperature range, extraordinary stability, and durability. Particularly, the VT/VRoom, IT/IRoom and QT/QRoom of PH-SA at 100 °C are separately up to 231.10%, 251.46% and 234.01%, the output efficiency of PH-SA is still higher than 100% at 120 °C. This study not only provides pioneering reference for the development of advanced PTM-TENG with enhanced output performance over a wide temperature range, but also greatly promotes the application of PTM-TENG devices in harsh environments.

Self-powered microbial blocking textile driven by triboelectric charges

Conventional methods of protecting against airborne pathogens, such as face masks, are typically associated with significant pressure loss and uncomfortable long-term wear. Alternative methods, such as antimicrobial textiles, can utilize nanomaterial-modified functional fabrics for effective microbial prevention, but suffer from limited treatment throughput, high cost, and potential toxicity from nanomaterial release. Herein, we develop a novel microbial-blocking textile using fabrics with opposite triboelectric properties of the outer and inner layers, which induces triboelectric charges by harvesting kinetic energy from human motion. The induced triboelectric negative charges at the outer textile layer achieve efficient airborne pathogen blocking based on electrostatic repulsion between the fabric and microbes. This self-powered, triboelectrification-induced microbial blocking system with optimized material (PTFE and nylon) and structure (rib knitted) achieves highly efficient microbial blocking (>95%) at a very high airflow rate of 2.0 m/s. In addition, the pressure drop for microbial blocking by this novel method is extremely low (<30 Pa). Our results demonstrate a promising method for rapid, self-powered blocking of airborne pathogens by incorporating triboelectric charges from human motion to meet vital public health needs.

An Advanced Strategy to Enhance TENG Output: Reducing Triboelectric Charge Decay.

The Internet of Things (IoT) is poised to accelerate the construction of smart cities. However, it requires more than 30 billion sensors to realize the IoT vision, posing great challenges and opportunities for industries of self-powered sensors. Triboelectric nanogenerator (TENG), an emerging new technology, is capable of easily converting energy from surrounding environment into electricity, thus TENG has tremendous application potential in self-powered IoT sensors. At present, TENG encounters a bottleneck to boost output for large-scale commercial use if just by promoting triboelectric charge generation, because the output is decided by the triboelectric charge dynamic equilibrium between generation and decay. To break this bottleneck, the strategy of reducing triboelectric charge decay to enhance TENG output is focused. First, multiple mechanisms of triboelectric charge decay are summarized in detail with basic theoretical principles for future research. Furthermore, recent advances in reducing triboelectric charge decay are thoroughly reviewed and outlined in three aspects: inhibition and application of air breakdown, simultaneous inhibition of air breakdown and triboelectric charge drift/diffusion, and inhibition of triboelectric charge drift/diffusion. Finally, challenges and future research focus are proposed. This review provides reference and guidance for enhancing TENG output.

Grounding strategy to promote the surface charge equilibrium and output performance of triboelectric nanogenerator

As the driving force for the flow of electrons in the external circuit, the quantity of triboelectric charges in the friction layers is critical important, more triboelectric charges will bring about the larger output power of a triboelectric nanogenerator (TENG). In this work, a grounding strategy is proposed and developed to further increase the triboelectric charge density of the friction layer and the output of TENG, which can break through the limitations of increasing the output of TENG by merely enhancing material’s property itself. By designing the external circuit and utilizing an additional ground electrode, the electrons in the electron donor layer can be replenished timely, which contributes to a 2 times improvement in output current and 10 times improvement in output power. Additionally, the grounding strategy is used to improve the performance of sound wave-driven TENG (STNG). We found that the improvement effect of the grounding strategy on STNG’s (GS-enhanced STNG) output increases with the increasing of sound frequency, and the output power of this GS-enhanced STNG can be increased by 200 times.