Dielectric Barrier Discharge Plasma Jet Research Articles

Impact of DBD Plasma Jet Treatment on the Enamel Surface of Primary Teeth.

The impact of cold atmospheric plasma (CAP) treatment on the enamel of twelve primary teeth (incisors, canines, and molars) collected from six children was examined in order to evaluate the possibility of using the CAP technique in dental applications. A radio-frequency dielectric barrier discharge (DBD) plasma jet operating at a voltage of 3.25 kV using a mixture of helium and oxygen as the working gas was used for the generation of plasma as part of the electro-technological method for the treatment of biological material. The plasma exposure time for the primary teeth was 5, 10, and 20 min. The properties of tooth enamel (color, contact angles, surface roughness, surface topography, elemental composition) were examined before (control) and after the plasma treatment. As shown by the results, the plasma treatment time is a key parameter that can induce desired features, such as whitening or improved wettability. However, with prolonged plasma treatment (20 min), the enamel surface may be permanently damaged. The cold-plasma-treated samples were characterized by a higher value of the brightness L* parameter and thus a lighter color, compared to the CAP-untreated teeth. It was also evidenced that the plasma treatment increased the hydrophilicity of tooth surfaces, and the contact angles effectively decreased with the time of the CAP treatment. The tooth surface also became much more heterogeneous and rough with much greater amplitudes in heights. The surface of the primary teeth after the CAP treatment lost its homogeneity, as evidenced by the SEM micrographs. The analysis of the elemental composition revealed only minor changes after the plasma process, which may suggest that the observed morphological changes in the enamel surface are mainly physical and are not a consequence of chemical reactions between the enamel and the reactive components of the cold plasma. Plasma treatment of teeth opens up new possibilities of using this method as an alternative to whitening or pre-treatment before other dental procedures.

Improving the Mechanical, Thermoelectric Insulations, and Wettability Properties of Acrylic Polymers: Effect of Silica or Cement Nanoparticles Loading and Plasma Treatment.

The acrylic polymer composites in this study are made up of various weight ratios of cement or silica nanoparticles (1, 3, 5, and 10 wt%) using the casting method. The effects of doping ratio/type on mechanical, dielectric, thermal, and hydrophobic properties were investigated. Acrylic polymer composites containing 5 wt% cement or silica nanoparticles had the lowest abrasion wear rates and the highest shore-D hardness and impact strength. The increase in the inclusion of cement or silica nanoparticles enhanced surface roughness, water contact angle (WCA), and thermal insulation. Acrylic/cement composites demonstrated higher mechanical, electrical, and thermal insulation properties than acrylic/silica composites because of their lower particle size and their low thermal/electrical conductivity. Furthermore, to improve the surface hydrophobic characteristics of acrylic composites, the surface was treated with a dielectric barrier discharge (DBD) plasma jet. The DBD plasma jet treatment significantly enhanced the hydrophobicity of acrylic polymer composites. For example, the WCA of acrylic composites containing 5 wt% silica or cement nanoparticles increased from 35.3° to 55° and 44.7° to 73°, respectively, by plasma treatment performed at an Ar flow rate of 5 L/min and for an exposure interval of 25 s. The DBD plasma jet treatment is an excellent and inexpensive technique for improving the hydrophobic properties of acrylic polymer composites. These findings offer important perspectives on the development of materials coating for technical applications.

Enhancing wetting and adhesion of stainless steel (SS304) surfaces with dielectric barrier discharge (DBD) plasma jet treatment

Enhancing the adhesion of coatings to metallic surfaces can be achieved through decontamination and increased surface energy. Among the various techniques used for functionalizing metallic surfaces, such as chemical etching, laser etching, flame treatment, and ultraviolet radiation; dielectric barrier discharge (DBD) plasma stands out as a promising option. It offers low-power, cost-effective, room-temperature operation and provides treatment with minimal alteration of subsurface properties. This study investigates using a DBD plasma jet to increase the treatment area, surface wettability, organic decontamination, and paint adhesion on stainless steel (SS304). The impact of different plasma treatments and aging times on the liquid contact angles and corresponding surface energies are experimentally examined. The results indicate that the surface energy of SS304 increases with treatment time. X-ray photoelectron spectroscopy (XPS) measurements are carried out to correlate this increase in surface energy to an increase in oxide bonds and decontamination of organic species, resulting in surface activation. However, it is observed that the plasma-treated surfaces exhibit no significant alterations in surface morphology, as confirmed through analyses of surface roughness and micro-hardness. Cross-hatch adhesion tests are carried out to demonstrate that the plasma surface treatment results in a significant improvement in surface adhesion to external coatings. Furthermore, the study evaluates the impact of DBD plasma jet treatment speed and dose on coating adhesion, providing valuable insights for making a trade-off between treatment quality and energy efficiency. The findings could extend the applicability of the DBD plasma jet to various areas, including anti-fogging surfaces, water harvesting, paints and coatings, and organic decontamination of surfaces.

Fluorine-free superhydrophobic surfaces by atmospheric pressure plasma deposition of silazane-based suspensions

Atmospheric plasma is used to deposit superhydrophobic fluorine-free thin films onto a substrate. In this process, a suspension of micron size silica particles in a silazane based precursor is deposited in a single step using a dielectric barrier discharge plasma jet moving above the substrate. Thanks to an optimized configuration between the suspension injection and the plasma jet, the silazane precursor can be polymerized on the substrate surface but also, on silica particles to form additional micro size particles. The experimental parameters for optimal deposition are discussed, with emphasis on those leading to the formation of this dual roughness surface caused by the arrangement of both silica particles and particles generated from the precursor plasma polymerization. The combination of these two different length scales for the roughness leads to a decreased wettability of the coated substrate and a water contact angle larger than 150°.

Bayesian Optimization of Low-Temperature Nonthermal Plasma Jet Sintering of Nanoinks.

In response to the escalating demand for flexible devices in applications such as wearables, sensors, and touch panels, there is a need for innovative fabrication approaches for devices made from nanomaterial-based inks. Subsequent to ink deposition, a pivotal stage in device manufacturing typically involves high-temperature sintering, posing challenges for heat-sensitive substrates. Nonthermal plasma jet sintering utilizing an atmospheric pressure dielectric barrier discharge (DBD) plasma jet enables sintering at room temperature and standard pressure, facilitating the sintering of printed nanoparticle films without compromising substrate or film surface integrity. However, determining optimal plasma jet sintering conditions can be challenging due to multiple processing variables with intricate interrelationships. This work employed Bayesian optimization (BO) and machine learning (ML) to identify optimal values for seven primary plasma jet sintering variables. Optimization yielded a 99.2% increase in the measured electrical conductivity for plasma jet-sintered indium tin oxide (ITO) films after five rounds of experiments. Moreover, the optimal sintering conditions achieved an electrical conductivity that was 81.4% of conventional furnace sintering at 300 °C, but was three times faster and with a peak substrate temperature below 47 °C. This result demonstrates the prospect of applying BO to optimize processing techniques for emerging low-temperature requirements.

Improvement of adsorption properties of coconut shell activated carbon using atmospheric pressure dielectric barrier discharge plasma jet

Improvement of adsorption properties of coconut shell activated carbon using atmospheric pressure dielectric barrier discharge plasma jet

Physical and chemical characteristics of plasma-activated water generated by hybrid dielectric barrier discharge and gliding arc discharge

This research explores the synergistic application of Dielectric Barrier Discharge (DBD) and Gliding Arc Plasma Jet (GAPJ) in a Hybrid Plasma Discharge (HPD) setup for enhanced water activation. The HPD system demonstrated balanced and sustained generation of reactive oxygen and nitrogen species (RONS), maintaining efficiency at higher specific input energy (SIE) values. Comparative analyses with DBD and GAPJ systems highlighted the superior performance of the HPD system in generating RONS and modifying water’s molecular structure. Key observations included a decrease in water’s pH and an increase in oxidation-reduction potential, total dissolved solids, and conductivity, stabilizing beyond 5 l min−1 airflow and 10 min of treatment. UV−Vis spectroscopy identified nitrites, nitrates, hydrogen peroxide, and nitrous acid, while Raman spectroscopy captured shifts in vibrational modes, particularly in librational and O–H stretching bands. These changes correlated with alterations in reactive species concentrations and pH levels. Overall, the HPD system emerged as a versatile and efficient approach for generating plasma-activated water, suitable for applications in microbial deactivation, surface sterilization, and electrocatalytic process optimization, offering stable and continuous production of reactive species across a range of SIE values.

Numerical simulation of dynamics behavior of pulsed-DC helium plasma jet confined by parallel magnetic field at atmospheric pressure

A two-dimensional axisymmetric fluid model is used to simulate the dynamics behavior of an atmospheric-pressure helium plasma jet in the presence of a parallel magnetic field. The plasma jet is generated in a coaxial dielectric barrier discharge (DBD) driven by pulsed direct-current voltage. Comparative analysis of the plasma jet with and without the parallel magnetic field indicates that a slightly thinner plasma sheath inside the tube is present with the parallel magnetic field as a result of the decreased accumulated electrons on the inner surface of dielectric tube. After the streamer propagates outside the tube, a little more concentrated electron distribution in the annular wall is observed by applying the magnetic field because of the reduced electron diffusion in the radial direction and the confinement effect of the magnetic field on the electrons in the avalanche heads. The tiny reduction in the length of plasma jet is attributed to the E × B drift of charged particles. These results demonstrate that the parallel magnetic field has no apparent effect on the propagation of the plasma jet, and it contributes little to the performance improvement of the coaxial DBD, which agrees well with the previous experimental observations. This little impact of the parallel magnetic field on the coaxial DBD plasma jet may result from negligible contribution of the memory effect to the sole discharge pulse as well as the weak confinement effect of the applied magnetic field on the surface electrons that moves along the magnetic field lines under electrostatic repulsion. Published by the American Physical Society 2024

Effect of target material on electrical properties of a two-electrode dielectric barrier helium plasma jet

In this paper we present electrical characterization of a dielectric barrier discharge plasma jet operating with He (2 slm and 3 slm) as working gas and interacting with Cu, polyethylene terephthalate and distilled H2O targets. We used a plasma jet with two copper electrodes wrapped around a glass tube. One electrode was powered by a high-voltage sinusoidal signal of 30 kHz, whereas the other electrode and the target holder were grounded. We have performed detailed investigation of the voltage and current waveforms, phase differences, volt–current (V–I) characteristics, calculated impedances and power deposition. The aim was to determine the influence of different target materials and their conductivity on the plasma properties. We calculated the total harmonic distortion factor that showed that the current through grounded electrode depends on the conductivity of the target. We also calculated the power delivered to the plasma core and the plasma plume regions and observed that the change in the target conductance influenced the power in both plasma regions. The experimentally characterized electrical circuit was simulated by a model of equivalent electrical circuit corresponding to the plasma-off and plasma-on regime. Voltage controlled current source was added as model of a streamer formed in plasma-on regime.

Inactivation of Staphylococcus aureus in water by dielectric barrier discharge plasma jet: The role of inorganic ions, organic matter, and turbidity

Pathogenic microorganisms in water pose a potentially serious threat to human health. As an advanced oxidation technology, plasma sterilization has been widely used to kill pathogens in water. However, few studies on the effects of various substances in natural water bodies, such as common ions (Ca2+, Mg2+, Cl−, SO42−, Fe2+), as well as natural organic matter (humic acid, HA) and turbidity (diatomite), on plasma sterilization. This study used a dielectric barrier discharge (DBD) plasma jet to inactivate Staphylococcus aureus (S. aureus) in pure water and simulated water containing the above substances. We systematically investigated how experimental parameters and water constituents affected S. aureus inactivation. Results showed that Ca2+, Mg2+, Cl−, natural organic matter (humic acid, HA), and turbidity (diatomite) inhibited inactivation, while Fe2+ and SO42− promoted it. Additionally, the MDA content, cell metabolic capacity, and cell integrity of S. aureus in pure water and simulated water system were detected before and after plasma treatment. The results showed that RS produced by plasma attacked the cell membrane of S. aureus, causing a rupture. RS also accelerated oxidative stress and disrupted cell metabolism, ultimately leading to cell death. Long-lived reactive species (RS) in water induced by plasma, such as (H2O2, NO3−, NO2−), had no significant effect in plasma inactivation. The positive role of short-lived reactive species (O2−, 1O2 and OH) in the inactivation of S. aureus was verified by ESR and quenching experiments, especially •O2−.

Hierarchical Structures Formed in an Atmospheric Pressure Plasma Jet by Polymerization from an Aerosol of Oxalic Acid Stabilized WO3–x Nanosheet Colloids: Toward High-Performance Electrochemical Devices and Sensors

The development of microstructures which combine high total surface area and high porosity is crucial for technologies such as electrocatalysis, electrochromics, and sensors. High deposition rate, composition control of deposition, and low processing temperature to retain active compositions are also desirable. To this end, this study describes combining colloidal sol chemistry with a nonthermal atmospheric pressure dielectric barrier discharge plasma jet to print hybrid inorganic/organic tungsten trioxide/oxalic acid (WO3–x/OA) microspheres. Injection of an aerosol of oxalic acid stabilized colloidal tungstic acid into an atmospheric pressure plasma jet results in the deposition of spherical structures in which the colloid is trapped within a plasma-polymerized organic shell. Subsequent low-temperature sintering produces hierarchical spherical shell-like structures comprising tungsten oxide nanosheets. Alteration of the gas flow rate changes the composition of the deposited material. The method has promise for the general preparation from colloidal precursors of porous materials of controlled morphology and composition with hierarchical microstructures, such as are required for applications in electrochemical devices and sensors which need a high ratio of surface area to volume and connectivity throughout the structure, yet also need a microstructure which is open for rapid exchange of reactants.

Surface modifications of aluminium and aluminium oxide induced by a treatment with a He-plasma jet and plasma electrolytic oxidation

Erosion of an aluminium oxide surface as well as a formation of an aluminium oxide coating on an aluminium substrate, comparable with erosion and oxide formation induced by plasma electrolytic oxidation (PEO), can be caused at atmospheric pressure conditions by a DBD-like (dielectric barrier discharge) plasma jet. Obtained experimental results conform a previously assumed similarity of the erosion mechanisms induced by the atmospheric pressure DBD-like plasma jet and PEO microdischarges. The mechanism of a predominantly inward growth of the oxide layer during PEO processing is substantiated based on a comparison of aluminium oxide erosion and oxide layer deposition by a treatment with the considered He-plasma jet and a PEO process.

Evaluation of Selected Properties of Dielectric Barrier Discharge Plasma Jet.

In the technological processes requiring mild treatment, such as soft materials processing or medical applications, an important role is played by non-equilibrium plasma reactors with dielectric barrier discharge (DBD), that when generated in noble gases allows for the effective treatment of biological material at a low temperature. The aim of this study is to determine the operating parameters of an atmospheric pressure, radio-frequency DBD plasma jet reactor for the precise treatment of biological materials. The tested parameters were the shape of the discharge (its length and volume), current and voltage signals, as well as the power consumed by the reactor for various composition and flow rates of the working gas. To determine the applicability in medicine, the temperature, pH, concentrations of H2O2, NO2- and NO3- and Escherichia coli log reduction in the plasma treated liquids were determined. The obtained results show that for certain operating parameters, a narrow shape of plasma stream can generate significant amounts of H2O2, allowing for the mild decontamination of bacteria at a relatively low power of the system, safe for the treatment of biological materials.

Degradation of sulfamethoxazole in water by dielectric barrier discharge plasma jet: influencing parameters, degradation pathway, toxicity evaluation

Sulfamethoxazole (SMX) is an antibiotic and widely present in aquatic environments, so it presents a serious threat to human health and sustainable development. A dielectric barrier discharge (DBD) plasma jet was utilized to degrade aqueous SMX, and the effects of various operating parameters (working gas, discharge power, etc) on SMX degradation performance were studied. The experimental results showed that the DBD plasma jet can obtain a relatively high degradation efficiency for SMX when the discharge power is high with an oxygen atmosphere, the initial concentration of SMX is low, and the aqueous solution is under acidic conditions. The reactive species produced in the liquid phase were detected, and OH radicals and O3 were found to play a significant role in the degradation of SMX. Moreover, the process of SMX degradation could be better fitted by the quasi-first-order reaction kinetic equation. The analysis of the SMX degradation process indicated that SMX was gradually decomposed and 4-amino benzene sulfonic acid, benzene sulfonamide, 4-nitro SMX, and phenylsulfinyl acid were detected, and thus three possible degradation pathways were finally proposed. The mineralization degree of SMX reached 90.04% after plasma treatment for 20 min, and the toxicity of the solution fluctuated with the discharge time but eventually decreased.

Comparison of characteristics of atmospheric pressure plasma jets using argon and helium working gases

Dielectric Barrier Discharge (DBD) plasma jets have been studied extensively in recent years because of their wide range of applications. In this work, we studied the performance of a DBD cold atmospheric pressure plasma jet with neutral argon gas experimentally and compared the produced DBD argon plasma with the helium jet in an equivalent operation. We investigated the effect of applied voltage, flow rate, and electrodes configurations on the argon and helium plume length and analyzed the physical parameters of the plasma plume, including discharge voltage, average gas, temperatures of the discharge gap, and jet velocity in plasma-on mode via Pitot glass tube as a speedometer. The results showed that by increasing any of the applied voltage or the flow rate at low values in different electrodes arrangements, plumes shape are more homogeneous and their length increases, but the helium plasma plume is transient from laminar to turbulent flow mode at higher flow rates. The temperatures of the discharge gap between the electrodes and their surroundings in the argon jet had a large increase over the helium jet in an equi-operational. Speedometer results show that plasma discharge affects the speed of argon jet more than helium.

Superhydrophobic and superoleophilic surfaces prepared by one-step plasma polymerization for oil-water separation and self-cleaning function

Efficient superhydrophobic and superoleophilic thin films for oil-water separation and self-cleaning were prepared using the atmospheric-pressure plasma polymerization of hexamethyldisiloxane (HMDSO). A dielectric barrier discharge (DBD) plasma jet with argon (Ar) was used for the deposition of the functional thin films onto several substrates. The oil-water separation membrane was synthesized by the plasma polymerization of HMDSO on fabric and offset printing paper. The superhydrophobic coatings were deposited on glass to demonstrate their self-cleaning ability. The hydrophobicity of the thin films was found to vary significantly, depending on the operating parameters such as the deposition time, applied voltage, and gas flow rate. The gaseous shield of the plasma jet also affected the hydrophobicity to a large extent. Nitrogen (N2) rather than inert gases such as Ar and He exhibited an excellent shielding effect against the interference of ambient air on the plasma jet. The wettability of the glass was completely switched from superhydrophilic to superhydrophobic with the water contact angle (WCA) reaching 165° and the sliding angle about 2°. In addition, superoleophilicity was obtained with the oil contact angle (OCA) reaching 0° under the optimal operating conditions.

D-Glucose Oxidation by Cold Atmospheric Plasma-Induced Reactive Species.

The glucose oxidation cascade is fascinating; although oxidation products have high economic value, they can manipulate the biological activity through posttranslational modification such as glycosylation of proteins, lipids, and nucleic acids. The concept of this work is based on the ability of reactive species induced by cold atmospheric plasma (CAP) in aqueous liquids and the corresponding gas–liquid interface to oxidize biomolecules under ambient conditions. Here, we report the oxidation of glucose by an argon-based dielectric barrier discharge plasma jet (kINPen) with a special emphasis on examining the reaction pathway to pinpoint the most prominent reactive species engaged in the observed oxidative transformation. Employing d-glucose and d-glucose-13C6 solutions and high-resolution mass spectrometry and ESI-tandem MS/MS spectrometry techniques, the occurrence of glucose oxidation products, for example, aldonic acids and aldaric acids, glucono- and glucaro-lactones, as well as less abundant sugar acids including ribonic acid, arabinuronic acid, oxoadipic acid, 3-deoxy-ribose, glutaconic acid, and glucic acid were surveyed. The findings provide deep insights into CAP chemistry, reflecting a switch of reactive species generation with the feed gas modulation (Ar or Ar/O2 with N2 curtain gas). Depending on the gas phase composition, a combination of oxygen-derived short-lived hydroxyl (•OH)/atomic oxygen [O(3P)] radicals was found responsible for the glucose oxidation cascade. The results further illustrate that the presence of carbohydrates in cell culture media, gel formulations (agar), or other liquid targets (juices) modulate the availability of CAP-generated species in vitro. In addition, a glycocalyx is attached to many mammalian proteins, which is essential for the respective physiologic role. It might be questioned if its oxidation plays a role in CAP activity.

Analysis of a nano-pulsed DBD Plasma jet for endoscopy and impact of excitation parameters

Cold atmospheric plasma induces various dose-dependent effects on living cells, from proliferation to necrosis. These effects are of interest in the field of therapeutic flexible endoscopy, although implementing an effective plasma delivery system represents a technical challenge. This work studies the impact of critical parameters on plume intensity, delivered reactive species (RS), and current administered to the target for the use of plasma in endoscopy. A 2 m long dielectric barrier discharge plasma jet was studied upon nano-pulsed high voltage excitation to increase plasma reactivity. The peak voltage, gas gap, pulse repetition frequency, and pulse width were varied while the power dissipated by the system and the optical emissions (with imaging and spectrometry) were measured. Two configurations were compared: the first one with the plume exiting freely in air, and the second one with the plume impinging an electrical equivalent of the human body. Finally, the current flowing through the capillary was measured at regular intervals along the tube with a Rogowski coil. Results show that (a) a conductive target increases the ratio of RS produced over the dissipated power, (b) increasing the pulse repetition frequency does not improve the RS production per pulse (e.g. through a synergetic, memory effect), (c) increasing the pulse width does not influence RS production but increases the dissipated power, and (d) current linearly leaks through the tube walls, and leaks are lower with nano-pulsed compared to sinusoidal excitation. Reactance and capacitance values of the system are analyzed based on the electrical equivalent circuit approach. Finally, displacement and discharge currents are discussed to bring power dissipation mechanisms to light and compare them between configurations. The conclusions drawn are important for the future design of safe and effective endoscopic plasma devices.

Helium Dielectric Barrier Discharge Plasma Jet (DBD Jet)-Processed Graphite Foil as Current Collector for Paper-Based Fluidic Aluminum-Air Batteries

A helium (He) dielectric barrier discharge plasma jet (DBD jet) was used for the first time for treating graphite foil as the current collector of a paper-based fluidic aluminum-air battery. The main purpose was to improve the distribution of the catalyst layer through modification and functionalization of the graphite foil surface. The plasma functionalized the graphite foil surface to enhance the wettability where the more hydroxyl could be observed from XPS results. The 30 s-He DBD jet treatment on the graphite foil significantly improved the battery performance. The best current density of 85.6 mA/cm2 and power density of 40.98 mW/cm2 were achieved. The energy density was also improved to 720 Wh/kg.

A comparative study of dielectric barrier discharge plasma device and plasma jet to generate plasma activated water and post-discharge trapping of reactive species

This work shows a comparative study of a change in properties of plasma-activated water (PAW) when prepared by using two different dielectric barrier discharge (DBD) configurations named a pencil plasma jet (PPJ) and a plasma device (PD). The air plasma produced from the DBD-PPJ and DBD-PD is characterized by voltage-current characteristics, and plasma species/radicals are identified using optical emission spectroscopy. Moreover, the present work emphasizes the trapping of reactive species (O3, NOx, etc.) carried by post-discharge residual gases during PAW production. The trapping of these gases' reactive species is carried out in water, which provides a useful by-product named plasma processed water (PPW). The results revealed a higher concentration of reactive oxygen species (dissolved O3 and H2O2) and a lower concentration of reactive nitrogen species (NO3− and NO2− ions) in PAW prepared by the DBD-PPJ configuration compared to the DBD-PD configuration. The trapping of reactive species (O3 and NOx) present in post-discharge residual gases is confirmed by determining the change in physicochemical properties and reactive oxygen–nitrogen species (RONS) concentration in virgin water used as a trapping medium. The high concentration of RONS in PPW showed a high concentration of reactive species in post-discharge residual gases and vice versa. Therefore, the reduction in reactive species downstream of post-discharge residual gases is shown by a substantial decrease in the concentration of RONS and physicochemical properties of PPW. Thus, PAW and PPW (by-product) prepared in this work could be used for multiple applications such as microbial inactivation, food preservation, and agriculture.