Dielectric Barrier Discharge Plasma Jet Research Articles

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.

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

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

Synergistic catalytic degradation of ciprofloxacin using magnetic carbon nanomaterial/NiFe2O4 promoted cold atmospheric pressure plasma jet: Influence of charcoal, multi walled carbon nanotubes and walnut shell

BackgroundCurrently, water polluted to antibiotics such as ciprofloxacin (CIP) has been a main concern for the ecosystem and environment. Hence, the removal of these emerging contaminants is essential. MethodIn this research, a hybrid process including magnetic carbon nanomaterial/NiFe2O4 promoted atmospheric non-thermal dielectric barrier discharge plasma jet (APJ) as an environmentally friendly hybrid system was evaluated for eliminating CIP from polluted synthetic effluent. Multi walled carbon nanotubes (MWCNTs), activated carbon formed using charcoal (ChAC), and the walnut shell was applied as the carbonous source. Besides, to solve the separation problem, the charcoal, as optimum sample, was magnetized with NiFe2O4 (ChAC/NiFe2O4) using the treatment solvothermal route. Characterizations of all carbon materials were carried out by X-ray diffraction, field-emission scanning electron microscopy, transmission electron microscopy, Brunauer-Emmett-Teller and Barrett-Joyner-Halenda and vibrating-sample magnetometer analyses. FindingThe degradation amount for 80 mg/L CIP gained 48.8, 80.8, and 98.1% over APJ system + walnut shell, MWCNTs, and ChAC, respectively, after 90 min at 15 kVp-p output voltage and 0.05 g/L of catalyst loading. The results showed the ChAC/NiFe2O4 (87.2%) had less removal than ChAC (98.1%), but it has magnetic properties that can facilitate the separation problem.

Dielectric Barrier Discharge Plasma Jet (DBDjet) Processed Reduced Graphene Oxide/Polypyrrole/Chitosan Nanocomposite Supercapacitors.

Reduced graphene oxide (rGO) and/or polypyrrole (PPy) are mixed with chitosan (CS) binder materials for screen-printing supercapacitors (SCs) on arc atmospheric-pressure plasma jet (APPJ)-treated carbon cloth. The performance of gel-electrolyte rGO/CS, PPy/CS, and rGO/PPy/CS SCs processed by a dielectric barrier discharge plasma jet (DBDjet) was assessed and compared. DBDjet processing improved the hydrophilicity of these three nanocomposite electrode materials. Electrochemical measurements including electrical impedance spectroscopy (EIS), cyclic voltammetry (CV), and galvanostatic charging-discharging (GCD) were used to evaluate the performance of the three types of SCs. The Trasatti method was used to evaluate the electric-double layer capacitance (EDLC) and pseudocapacitance (PC) of the capacitance. The energy and power density of the three types of SCs were illustrated and compared using Ragone plots. Our experiments verify that, with the same weight of active materials, the combined use of rGO and PPy in SCs can significantly increase the capacitance and improve the operation stability.

Non-thermal plasma multi-jet platform based on a flexible matrix.

A new plasma source design that merges the main characteristics of capacitive dielectric barrier discharge (DBD) and cold atmospheric plasma jet (CAPJ) is discussed. The DBD system contains a flexible, porous matrix consisting of silica aerogel, which is comprised between two biased electrodes. The helium flow supply subjected to a sinusoidal voltage of around 5 kV in amplitude and 15 kHz in frequency provides a set of plasma jets that propagates more than 1cm beyond the active DBD region. The studied plasma multi-jet system consists of an array of three aligned jets that flow in the laminar regime, and it is intended for treating the surfaces of 3D objects and large areas. CAPJ performance is discussed as a hypothetical morphing source in flat and bent configurations. Electrical characterization and optical emission spectroscopy diagnostics have provided current-voltage waveforms and the composition of the CAPJ through the aerogel layer, respectively. This novel source is promising for biomedical applications that require full adaptation of plasma parameters to delicate samples, such as wound healing and treatment of surgical margins in plasma-based cancer surgery.

Properties of DBD Plasma Jets Using Powered Electrode With and Without Contact With the Plasma

An experimental investigation comparing the properties of plasma jets in dielectric barrier discharge (DBD) configurations using a powered electrode with and without a dielectric barrier, while keeping a second dielectric barrier over the grounded electrode, is reported in this work. For this purpose, two different power sources were used to produce the plasma jets, with one of them producing a pulsed high-voltage (HV) output and the other one producing a pulse-like HV output, which consists of a damped sine HV waveform. Measurements of plasma parameters were performed for both configurations using argon and helium as working gases. As a result, if the pulsed power source is used, significant differences were found in discharge power ($P_{plasma}$), rotational and vibrational temperatures ($T_r$ and $T_v$, respectively) when switching from one configuration to the other. On the other hand, using the pulse-like HV only the $P_{plasma}$ parameter presented significant differences when switching the electrode's configuration. For the pulsed source it has been observed that despite the remarkable increase in $P_{plasma}$ when changing from the double barrier configuration to the single barrier one, the values obtained for $T_r$ and $T_v$ also increased, but not in the same proportion as the increase in $P_{plasma}$, which suggests a non-linear dependency between temperatures and discharge power in the plasma jet. As an example for application of plasmas in both configurations, tests in an attempt to remove copper films deposited on alumina substrates were performed and, as a result, there was significant material removal only when the powered electrode was in contact with the plasma. As a general conclusion, if higher power is really required for some application it is better to use this configuration.

Formation and behaviour of plasma spots on the surface of titanium film

Numerous studies have shown that dielectric barrier discharge (DBD) and DBD-like plasma jets interact with a treated surface in a complex manner. Eroded traces after treatment cannot be explained by conventional plasma-surface interaction theory. The mechanisms of a controlled formation of these plasma objects is still unclear. In this work, the authors show that the formation rate and characteristics of eroded traces, treating a titanium surface, can be controlled by process design and the combination of materials used. A thin (0.45 µm) layer of titanium film is deposited onto a glass substrate and is then treated in the effluent of a non-equilibrium atmospheric pressure plasma jet (N-APPJ) operated with argon or krypton flow. Plasma spots with diameters ranging from 100–700 µm are observed using an intensified digital camera on the titanium film surface. These plasma objects are strongly inhomogeneous, forming a core with a very high current density and leave erosion holes with diameters of about 1 µm. By using krypton as a working gas, effective erosion of the titanium substrate can be shown, whereas by using argon no traces are detected. For the latter case, traces can be provoked by deposition of a thin aluminum layer on top of the titanium substrate, by creation of artificial scratches or by an additional swirling flow around the discharge. Based on the experimental results presented in this and previous papers, it is assumed that plasma spots with dense cores are produced by an interaction of micro-vortices within the plasma channel and by the formation of an extremely high axial magnetic field. This assumption is confirmed by destruction of the treated surface material, extraction of paramagnetic atoms and toroidal substrate heating, which is most likely caused by a helical current of the plasma spot.

Effect of dielectric barrier discharge plasma jet on bactericidal and human dermal fibroblasts adult cells: In vitro contaminated wound healing model

Commercial dielectric barrier discharge plasma jet (DBDPJ) with helium gas was used as a handy cold atmospheric pressure plasma tool to study the DBDPJ effects on contaminated wound healing. The contaminated wound was modeled into three parts: bacteria as the contaminant origin, bacterial biofilm as the simulated bacterial contaminant layer on the wound, and the wound cells. The bacteria were Staphylococcus aureus and Pseudomonas aeruginosa and the wound cells were human dermal fibroblasts adult (HDFa) cell. DBDPJ treatments were carried out on the three model parts respectively to study the DBDPJ effects on bactericidal and wound cell survival as functions of the plasma conditions including the plasma dissipated power and exposure time and the role played by the plasma radical species. The results demonstrated that DBDPJ could effectively kill the bacteria without significant side effect on the HDFa cell. Optimal plasma conditions were determined and are ready for clinical uses.

Effect of insulating oil covering electrodes on the characteristics of a dielectric barrier discharge

In this study, the effects of the fluid cooling and electric field line deformation were investigated in a dielectric barrier discharge (DBD) plasma source. The DBD plasma jet is improved by covering the ground electrode and a power electrode with insulating oil. We obtained positive results as insulating oil prevents arc formation, while it improved the supplied power and plasma jet length, and increased radical production. Radical production of this nonthermal plasma jet is studied with polyvinyl alcohol–potassium iodide liquid.