Electric Charge Accumulation Research Articles

Long-lifespan and sterilizable face masks leveraging the power of light and electricity

The rapidly evolving virus and worsening air pollution have created a huge demand for face masks. However, most commercial masks are limited in their ability of long-time filtering air particulates and killing pathogens. We here present a highly germicidal, self-charging, and long-lifespan mask based on the synergistic effect of light (photocatalysis of CuO-ZIF-8) and electricity (piezoelectricity of PVDF-TrFE). Specifically, we synthesize CuO-ZIF-8 nanomaterials that are 99.999 % bactericidal against E. coli and S. aureus in PBS buffer under 2 h of simulated solar irradiation. Air filters made of CuO-ZIF-8 nanocubes and PVDF-TrFE nanofibers possess a low pressure drop of 90 Pa and high filtration efficiency of 99.01 % for 0.3 µm particles thanks to the piezoelectric energy conversion from breathing to electric charge accumulation. The filtration efficiency keeps up to 94.2 % for an ultralong 30 h, 6–7 times longer than surgical masks. This work sheds new light on developing public protective materials featured with photocatalytic antibacterial and piezoelectric enhanced adsorption.

Оценка электростатических свойств средств защиты головы, применяемых во взрывопожароопасных зонах

Problems of prevention of explosions and fires caused by the accumulation of electrostatic charge and the following discharge able to ignite an explosion and hazardous medium are well known in global practices. These conditions are specific, inter alia, to engineering industries and determined by the technological necessity to wash or process product surfaces in the medium of flammable liquids. At the same time, explosion and fire safety is primarily ensured by the requirements for non-excess of the minimum value of ignition of medium containing flammable liquids. As a potential source of accumulation of electrostatic charges, personal head protection equipment (safety helmets) required for mechanic safety is considered. Their base and tooling are usually made of polymer materials naturally prone to electrification. The article aims to resolve the problem of assessing the potential accumulation of electric charges during the contact of the scalp with elements of safety helmets. In conditions of current production, the electrostatic potential relative to the earth occurring on the scalp, cheeks, chin, and elements of safety helmet during putting on and off has been studied; the results of the study are provided. The energy of accumulated charges has been determined and compared with the value of minimum energy of ignition of different gasoline brands; conclusions regarding the sufficiency of energy to generate a discharge capable of causing an initiating ignition of flammable liquids have been made. The impact of the length of the employee’s scalp hair on the level of accumulation of electrostatic charges potentially causing ignition of the working medium containing flammable liquids has been determined. The results of the study can be used for the development of a methodology to assess a potential spark hazard occurring due to contact electrification during the use of safety helmets in conditions of explosion and fire-hazardous media and potentially causing fire and explosion.

Protective and Collision‐Sensitive Gel‐Skin: Visco‐Elastomeric Polyvinyl Chloride Gel Rapidly Detects Robot Collision by Breaking Electrical Charge Accumulation Stability

Human–robot collaboration (HRC) is effective to improve productivity in industrial fields, based on the robot's fast and precise work and the human's flexible skill. To facilitate the HRC system, the first priority is to ensure safety in the event of accidents, such as collisions between robots and humans. Therefore, a protective and collision‐sensitive robot skin, named Gel‐Skin is proposed to guarantee the safety in HRC. The Gel‐Skin is composed of polyvinyl chloride (PVC) gel, which is a functional material with piezoresistive characteristics and impact absorption capability. In particular, the PVC gel has a distinctive piezoresistive property that the relation between mechanical pressure and electrical resistance is tunable depending on an applied voltage. When a voltage is applied to the PVC gel, the electrical charges are accumulated around the anode and it shows increased piezoresistive sensitivity. In this study, it is verified for the PVC gel to exhibit the 4.78 times higher sensitivity by simply applying a voltage. This novel physical phenomenon enables the Gel‐Skin to detect the collision rapidly. Finally, the Gel‐Skin is applicated to a real robot system and it is verified that the Gel‐Skin can detect a collision and absorb impact to ensure safety.

Microwave Optical Switches Metal–Semiconductor–Metal Schottky based on GaAs

Interdigitated metal–semiconductor–metal (MSM) photodetectors have received considerable attention for applications in microwave optical phoswitches. The impulse response of photoswich interdigitated fabricated metal-semiconductor- on GaAs metal non-intentional doped (NID) absorbing layer is investigated. The photodetector MSM is introduced in the microwave lines have active surfaces of 3x3 m2 and electrode spacing of 0.2, 0.3, 0.5 and 1 m.. The photocurrent response was measured after excitation and we found that the screening of the dark electric field and charge accumulation exceedingly modify the drift conditions of the photogenerated electrons and holes in active region of the MSM photoswich.

Enhanced plasma jet generation through numerical integration and dielectric influence analysis

This paper reports a study on the production of plasma jets that are out of equilibrium through numerical solutions of electron energy distribution function using a self-consistent methodology. The approach includes the integration of the continuity, momentum, and Poisson equations, which allows the use of the mean electron energy to fit the transport and source coefficients. The paper concurrently presents an analysis of cold plasma generation in a tube. This investigation utilizes COMSOL Multiphysics software to simulate the electric field, potential, and electron density in space. Moreover, the study examines how the dielectric’s permittivity impacts plasma propagation. The simulated outcomes are compared with experimental and numerical results. As electron density, ionization rate and electric potential vary during plasma propagation on a dielectric surface, and the permittivity of dielectric materials increases, it promotes an increase in electron density around it. This, in turn, accelerates the ionization front, indicating efficient polarization and accumulation of electric charges, specifically electrons, near the dielectric surface.

New Insights into the Simulations of Electric Currents for Discharges and ULF Magnetic-Field Perturbations: Applications to the Popocatepetl Volcano and a Micro-Discharge Model

The noise-like behavior of geomagnetic anomalies observed in Tlamacas station (the Popocatepetl volcano, Mexico), linked to the ionization produced by intensive radon release, is presented in the experimental part of the study. The magnetic-field perturbations produced by electrical currents due to micro-discharges on the terrain irregularities are considered in a theoretical model. The simulations demonstrated that the discharge mechanism can generate perturbations with magnitudes of up to 1–10 nT in the ultra-low frequency (ULF)) range of 10−3–10−1 Hz. ULF Magnetic-field perturbations can be higher within storm-weather conditions under an accumulation of electric charges in clouds in the mountainous regions.

Piezoelectric power generation from tyres

The piezoelectric effect enables the conversion of mechanical energy, resulting from the contact between a vehicle's wheel and the road, into electrical energy. Piezoelectricity refers to the accumulation of electric charge in specific solid materials, such as ceramics, human bone, and DNA, in response to mechanical stress. The objective of this project is to enhance electricity generation in an environmentally friendly manner. By utilizing technological advancements, it becomes possible to convert wasted vibrational mechanical energy from the vehicle's tire into electrical energy, leading to both cost-effectiveness and environmental sustainability. To achieve this, piezoelectric patches are strategically positioned within the wheel rim. When these patches come into contact with the road and are subjected to the weight of the vehicle, electricity is generated. In our project, we will employ polyurethane foam to safeguard the piezoelectric patches, which will be situated inside the bicycle's tire. This setup aims to generate sufficient energy to charge a battery. Consequently, the electrical energy stored in the wheels will be transformed into light energy through the utilization of the piezoelectric patches.

Exploring the biocapacitance in M3C-based biosensors for the assessment of microbial activity and organic matter

Reliable monitoring of microbial and water quality parameters in freshwater ecosystems (either natural or human-made) is of capital importance for improving both the management of water resources and the assessment of microbially-driven bio-geo-chemical processes. In this context, bioelectrochemical systems (BES), such as microbial three-cell electrodes (M3C), are very promising devices for their use as biosensors. However, current experiences on the use of BES-based devices for biosensing purposes are almost exclusively limited to water-saturated environments. This limitation hampers the use of this technology for a wider range of applications where the biosensor may work discontinuously (such as discontinuously saturated ecosystems). Discontinuous operation of M3C-based biosensors creates an electric current peak immediately after the reconnection of the system due to electron accumulation, in a process known as biocapacitance. The present work aimed at quantifying the bioindication potential of biocapacitance for the assessment of key ecosystem parameters such as microbial metabolic activity and biomass, as well as organic matter concentration. Significant linear regression coefficients (R2 > 0.9) were found for all combinations of parameters tested. Moreover, for most of the ecological parameters assessed, an electric charge accumulation of 1–5 min (biocapacitance elapsed time) and discharge of 5 min was enough to get reliable information. In conclusion, we have demonstrated for the first time that biocapacitance in M3C-based biosensors can be used as a proxy parameter for the assessment of microbial activity, microbial biomass and organic matter concentration in a model nature-based ecosystem.

The role of the solving strategy in electrokinetic transport modelling in saturated porous media

The characterisation of the reactive transport of solutes is a complex problem that is applied in many fields of industry and environmental management. However, this problem has been treated with multiple mathematical approaches. This paper reviews several strategies for solving the different physical constraints that must be applied to this type of problem using COMSOL Multiphysics. The number of mass balance equations of the chemical species is evaluated together with the use of Gauss’s Law or electric charge balance to analyse the no-charge accumulation or electroneutrality conditions as electrical constraints. Problems of natural diffusion and electrokinetic transport in saturated porous materials are evaluated for electroconductive and nonconductive solid matrices in both potentiostatic and galvanostatic operation modes. Of all the solving strategies proposed, only one is valid and consistent for all types of problems presented. This approach is based on posing a mass balance equation of less (N-1) than the species in solution (N), solving for the mass of the missing species by electroneutrality and imposing the condition of no electric charge accumulation on the charge balance equation.

Plasticizer structural effect for sustainable and high-performance PVC gel-based triboelectric nanogenerators

A triboelectric nanogenerator (TENG) produces electrical energy by the accumulation of electric charges when two different materials rub against each other. In this study, the characteristics, and stabilities of adipate PVC gels with different adipate plasticizers were investigated for the development of triboelectric nanogenerators (TENGs) for sustainable energy harvesting. Various plasticizers with different numbers of carbon atoms in the alkyl chain were used to synthesize PVC gels, and their triboelectric properties, permittivities, and electrical conductivities were evaluated. In particular, we investigated the relationship between the surface charge dissipation rate and electrical resistivity of the PVC gel, which can maximize the TENG performance. The DOA5-based PVC gel TENG showed the highest output performance (198 V, 15.6 µA, and 384 µW/cm2) and stable output performance without plasticizer leakage for over 30 days at a high temperature. The developed TENG can be used as a power source for small electronic devices, maintaining a stable and high-output performance with high durability, making it ideal for self-powered systems in harsh environments requiring continuous power supply.

Enhanced nonlinear conductivity of silicone rubber composites with hybrid graphene and alumina for cable accessory

The electric field distortion and charge accumulation in cable accessories are still challenges for high voltage direct current transmission (HVDC). Using silicone rubber (SR) based materials with nonlinear conductivity properties can ameliorate these problems in cable accessories. Herein, SR composites with hybrid filler network were prepared by adding graphene (G; 0.25 phr) and alumina particles (Al2O3; 5–40 phr) to SR to obtain good nonlinear conductivity and relative high breakdown strength, along with thermal conductivity. The SEM results showed that graphene was well dispersed between Al2O3 particles and a hybrid filler network was constructed in the SR matrix. The G/Al2O3/SR composites exhibited favorable nonlinear electrical conductivity properties and thermal conductivity properties while sustaining high breakdown strength under different electrical and temperature field. The non-linear conductivity α of the 0.25G/40Al2O3/SR composite reached 6.68 at 23 °C, whereas the breakdown field strength E0 of 49.1 kV/mm could comparable to that of pure SR. Moreover, the thermal conductivity of 0.25G/30Al2O3/SR was 0.28 Wm−1K−1 at 23 °C, which increased by 114.98% compared to pure SR. This work suggests the promising application of G/Al2O3/SR composites as cable accessory.

Study of the synthesis of carbon-containing materials based on modified pine bark for the accumulation of electric charge

Study of the synthesis of carbon-containing materials based on modified pine bark for the accumulation of electric charge

Role of charge carriers in long-term kinetics of polyurethane electroactuation

Previous work has shown that dielectrophoretic body forces resulting from permittivity and conductivity heterogeneities only partially contribute to the overall electromechanical deformation of segmented polyurethanes (PUs). In this work, we studied the experimental kinetics and electric current of PU thin films over a long time period (1–105 s) for different applied electric fields. Then, we thoroughly analyzed the drift behavior of electric carriers and its macroscopic effect using simple modeling and numerical simulation. The main assumption is that the macroscopic deformation results from the accumulation of electric charges near the electrodes, leading to local stretching. Assuming that the mobilities of negative and positive carriers are different, their migration towards the electrodes will have different kinetics. A preliminary simulation attempt using a single set of parameters, supports these assumptions, and leads to a correct bending amplitude and current evolution according to the applied electric field. Furthermore, the resulting compression is consistent with the observed electrostriction.

Mechanism and control of triboelectrification on oil-solid interface and self-powered early-warning sensor in petroleum industry

Oil–solid triboelectrification in the petroleum industry has been extensively studied because of its severe electrostatic hazards. Here, the manipulation strategies of oil–solid interface electrification were proposed. The influence of surface structure, composition, and interface wettability of the solid wall on the oil–solid triboelectrification based on the friction of aluminum/alumina sheet and liquid paraffin was systematically studied for controlling oil–solid friction charges. In comparison with surface structures, the output performance was very sensitive to the surface components. For instance, the output performance of 1 H, 1 H, 2 H, 2 H–perfluorooctyltrichlorosilane–modified alumina is 114 times greater than that of octadecyltrichlorosilane–modified alumina. For interface wettability, it enhances the generation and accumulation of net charge. A fully packaged oil–based triboelectric nanogenerator is a promising sensor to reflect the electrification behavior of water in the oil in situ. When the volume ratio of water is 4.7%, the charge in the oil is even increased by 6.5 times. Therefore, to avoid the continuous accumulation of electric charge in the oil causing fire or explosion, we designed a concealed wireless early-warning sensor to alarm when the charge in the oil reaches a critical predetermined value. This study may provide theoretical basis and technical guidance for the prevention of oil–solid friction charges in the petroleum industry.

Dielectric breakdown driven by flexoelectric and piezoelectric charge generation as hotspot ignition mechanism in aluminized fluoropolymer films

Using multiphysics simulations and experiments, we demonstrate that dielectric breakdown due to electric charge accumulation can lead to sufficient hotspot development leading to the initiation of chemical reactions in P(VDF-TrFE)/nAl films comprising a poly(vinylidene fluoride-co-trifluoroethylene) binder and nano-aluminum particles. The electric field (E-field) development in the material is driven by the flexoelectric and piezoelectric responses of the polymer binder to mechanical loading. A two-step sequential multi-timescale and multi-physics framework for explicit microscale computational simulations of experiments is developed and used. First, the mechanically driven E-field development is analyzed using a fully coupled mechanical–electrostatic model over the microsecond timescale. Subsequently, the transient dielectric breakdown process is analyzed using a thermal–electrodynamic model over the nanosecond timescale. The temperature field resulting from the breakdown is analyzed to establish the hotspot conditions for the onset of self-sustained chemical reactions. The results demonstrate that temperatures well above the ignition temperatures can be generated. Both experiments and analyses show that flexoelectricity plays a primary role and piezoelectricity plays a secondary role. In particular, the time to ignition and the time to pre-ignition reactions of poled films (possessing both piezoelectricity and flexoelectricity) are ∼10% shorter than those of unpoled films (possessing only flexoelectricity).

Impedance spectroscopy method for testing moistened wheat crops

The authors presented the results of a study of the electrical and dielectric characteristics of wetted wheat grains by measuring their complex electrical resistance (impedance Z) in a wide frequency range (from 1 Hz to 100 MHz). The results of electrical impedance measurements of grains with surface or volumetric moisture content under different experimental conditions can provide useful information on the properties of the biological tissues of grain crops. These results can also be used to develop a new type of impedance sensor for testing grain quality and moisture content. The authors used well-dried wheat grains and grains saturated with moisture and saline as objects of research. A major problem in grain impedance measurements is the selection of a suitable electrode material to be placed on the end surfaces of the samples. The electrodes must ensure reliable contact with the grain and have a minimum transient resistance. The end surfaces of the pressed samples were reinforced with a protective dielectric ring to prevent transverse deformation. These contacts provided a transition resistance between 1-2 ohms. The authors have identified processes of accumulation of electric charges near the surface of metal electrodes at low frequencies and on internal grain structures, leading to an increase in the dielectric permittivity and dissipation factor. The behavior of the active and reactive components of the impedance at higher frequencies is determined by dielectric relaxation processes. The obtained impedance spectra were compared with the spectra of the most suitable equivalent electrical circuits. The radio components of the circuits provide information about the basic mechanisms of alternating electric current flow through the complex inhomogeneous structure of the grain. The authors found that moistening the grain with saline water enhances the process of accumulation of electric charges and affects the dispersion of the real and imaginary components of the impedance.

Biintercalate formed on the basis of 2D semiconductor matrix, ferroelectric and ferromagnetic phases

The paper presents the structural-energy, electrically conductive and polarization properties of biintercalant clathrate GaSe≪NaNO2> +<FeCl3≫. The existence of two modifications of the crystal structure with interplanar distances c1 = 16.072 Å and c2 = 15.977 Å was established by X-ray diffractometry. The сurrent-voltage characteristics of the biitercalant clathrate GaSe≪NaNO2> +<FeCl3≫ acquires a hysteresis form, which indicates the accumulation of electric charge at the interfacial boundaries. The spectrum of impurity energy levels was established by the method of thermally stimulated discharge with short-circuited contacts in the temperature range from 240 to 340 K, which testifies to the relaxation of the hetero-charge and the quasi-continuity of energy states.

Vacuum current-carrying tribological behavior of MoS2-Ti films with different conductivities

Current-carrying sliding is widely applied in aerospace equipment, but it is limited by the poor lubricity of the present materials and the unclear tribological mechanism. This study demonstrated the potential of MoS2-based materials with excellent lubricity as space sliding electrical contact materials by doping Ti to improve its conductivity. The tribological behavior of MoS2-Ti films under current-carrying sliding in vacuum was studied by establishing a simulation evaluating device. Moreover, the noncurrent-carrying sliding and static current-carrying experiments in vacuum were carried out for comparison to understand the tribological mechanism. In addition to mechanical wear, the current-induced arc erosion and thermal effect take important roles in accelerating the wear. Arc erosion is caused by the accumulation of electric charge, which is related to the conductivity of the film. While the current-thermal effect softens the film, causing strong adhesive wear, and good conductivity and the large contact area are beneficial for minimizing the thermal effect. So the moderate hardness and good conductivity of MoS2-Ti film contribute to its excellent current-carrying tribological behavior in vacuum, showing a significant advantage compared with the traditional ones.

Triboelectric effects in catalyst feeders of fluidized-bed polymerization reactors

Solid material in fluidized-bed polymerization reactors consists of two components with different triboelectric properties. The main material is a granular polymer with the particle size from ∼100 to >1000 μm. The second component, very small in volume, is fresh catalyst, spherical particles with the diameter from 20 to 40 μm. Small loads of catalyst particles are periodically fed into the reactors through narrow metal tubes with a gas flow (nitrogen or monomer).This catalyst injection process leads to accumulation of a significant electric charge on the catalyst particles. This paper describes results of laboratory experiments aimed at determining sources of electrostatics generation in spherical catalyst particles passing through narrow tubes, a possible mechanism of the charging and methods of its mitigation.

Hydrated zirconia nanoparticles as media for electrical charge accumulation

Hydrated zirconia nanoparticles as media for electrical charge accumulation