Pressure Plasma Jet Research Articles

Atmospheric pressure plasma jet for respiratory face masks decontamination and re-use: Considerations on microbiological efficacy, material impact and product lifecycle.

Disposable filtering face piece respirators (FFRs) are not approved for reuse as standard of care. However, lessons learnt from the SARS-CoV-2 pandemic, FFRs decontamination and reuse may be needed as crisis capacity strategy to ensure availability in medical facilities. We studied a decontamination methodology based on atmospheric pressure plasma technology, which allows for rapid, contact-free decontamination without utilisation of harmful chemicals, and suitable to access small pores and microscopic filters openings. Promising performances in terms of bioburden reduction (Log6) were achieved while imparting mainly transient chemical surface modifications to the masks filtering layers. The plasma decontamination process proposed was also considered in terms of the environmental impact of re-use technology for FFR medical devices in order to understand its sustainability. This study assessed the feasibility of an atmospheric pressure plasma approach for the decontamination of disposable filtering face piece respirators (FFR) or respiratory masks commonly used in hospital settings.

Atmospheric pressure plasma jet deposition of TiO2 layer on alumina/epoxy to improve electrical properties

In gas-insulated lines, basin-insulators can accumulate charge under non-uniform electric fields, distorting the field distribution and potentially causing surface flashover, which threatens the stability of power systems. In this study, Atmospheric Pressure Plasma Jet (APPJ) technology was used to deposit TiO2 on the surface of alumina/epoxy (Al2O3/EP) composites. The impact of deposition of TiO2 layer on the surface morphology and chemical composition of Al2O3/EP was studied using testing methods such as Scanning Electron Microscope, X-ray photoelectron spectroscopy, Fourier Transform Infrared Spectrometer, and Energy Dispersive Spectrometer. It was found that APPJ creates a dense, rough Ti-O layer on the Al2O3/EP surface, which bonds tightly with the substrate. The efficacy of APPJ was found to depend on processing time, with optimal results observed at 3 min, DC and AC flashover voltages increased by 29.6% and 15.7%, respectively. TiO2 layer enhances the conductivity of the resin and shallows trap levels. Through the synergistic effects of various factors, surface charges are efficiently dissipated and evenly distributed. This study not only reveals the physicochemical process of TiO2 deposition via APPJ but also integrates surface characteristics with electrical performance. The findings offer a new strategy to enhance surface flashover voltage and ensure equipment safety.

Atmospheric pressure plasma jet for surface treatment: a review

Atmospheric pressure plasma jet for surface treatment: a review

Ultra-fast etching of photoresist by reactive atmospheric-pressure thermal plasma jet with surface temperature measurement

Abstract Atmospheric-pressure reactive thermal plasma jet (R-TPJ) with Ar and O2 gas mixture was applied to etching of photoresist (PR) on silicon wafer. An optical interference contactless thermometry (OICT) and optical emission spectroscopy were carried out to clarify the relationship between the etching rate, amount of atomic oxygen radicals, and PR surface temperature. The results show that O2 flow rate and surface temperature are obviously related to the etching rate of PR. The R-TPJ irradiation with input current at 60 A reaches surface temperature of 720 K within 7 ms and achieved etching rate of 84 μm/s.

Preparation and Characterisation of CdO@Au Nanoparticles by Hybrid System Using Laser Ablation and Plasma Jet Methods for Cytotoxicity Against Rat Embryonic Fibroblast Cell Line

The purpose of the research is to see if cadmium oxide@gold (CdO@Au) nanoparticles produced using the laser ablation and plasma jet method in deionised water (DW) solution could be a viable alternative to typical materials in cytotoxicity of rat embryonic fibroblast (REF) normal cell line. The cadmium nanoparticle core was prepared using a Q-switched Nd:YAG laser at a wavelength of 1,064 nm, with laser pulse energies varying between 800 mJ and 1,000 mJ over 500 shots. Gold nanoparticles shell prepared using atmospheric pressure plasma jet. The structural analysis process used X-ray diffraction (XRD) and UV-vis absorption spectroscopy to study the surface plasmon resonance (SPR) to follow the fast changes in the nanoparticles (NPs) colloidal solutions brought on by the interaction between Au sheets and CdO core. From UV-visible transmittance and absorbance spectra, it was observed that the transmittance pattern that can be obtained decreases. At the same time, the energy gap increases with the increase of laser energy, and this may be due to the increase in absorption. The XRD investigation revealed that the polycrystalline structure of CdO@Au NPs and their preferred orientation along (111) direction. The normal REF cell line was employed in the study to investigate the cytotoxicity of CdO@Au nanoparticles. After 48 h of exposure, the CdO@Au NPs displayed the maximum toxicity at a concentration of 100%.

Measurements of power dissipated in an atmospheric pressure plasma jet device with double plasma discharge ignition

Measurements of power dissipated in an atmospheric pressure plasma jet device with double plasma discharge ignition

Investigating the influence of Ar or O2 carrier flow rate on electrical insulation resistance of SiO2 layer deposited by atmospheric pressure plasma jet technology

Investigating the influence of Ar or O2 carrier flow rate on electrical insulation resistance of SiO2 layer deposited by atmospheric pressure plasma jet technology

Nanosecond resolved vibrational kinetics of CO2 in CO2/N2 mixtures measured in a pulsed discharge jet

Abstract This work studies the vibrational kinetics of CO2/N2 mixtures in a nanosecond pulsed near atmospheric pressure plasma jet. Quantum-cascade laser absorption spectroscopy is used to measure the populations of rovibrationally excited states of CO2 without any assumption on a particular vibrational distribution function and with a variable time resolution of as high as 8 ns. These studies are complemented by measurements using electric field induced second harmonic generation and electrical measurements to characterize the discharge. The nanosecond pulsing, combined with fast diagnostics, allows for a temporal separation of processes on different timescales, namely, electron impact excitation (e-V) during the discharge and vibrational-vibrational (V-V) and vibrational-translational (V-T) transfer in the afterglow. During the discharge, the Fermi resonant 10 0 01 state is excited at a higher rate than the energetically close 02 2 01 state of the bending mode, leading to different effective vibrational temperatures. In the afterglow, the two vibrational temperatures converge to a combined vibrational temperature T 12 within 200 ns . This equilibration process is observed here for the first time. In the afterglow, the populations of all vibrational states increase for several 10 μ s . This can be attributed to the V-V transfer from N2 to the asymmetric stretch mode of CO2 and from the latter to the other vibrational modes of CO2. An increase of the N2 admixture, which acts as an energy reservoir for the CO2, enhances the increase of the vibrational populations of CO2 in the afterglow and slows down the decay of the asymmetric mode in the late afterglow through continuous replenishment via V-V transfer. The combined data of all diagnostics allow for a detailed comparison with kinetic models.

Dibutyl phthalate degradation and toxicity assessment based on hydroxyl radicals generated by plasma jet

Phthalate esters such as dibutyl phthalate (DBP) are widely used as plasticizers in various industries and are known to cause water pollution reaching 15.7 mgL-1 in freshwater and 0.01 mgL-1 in seawater. This study investigated the effectiveness of DBP degradation using an atmospheric-pressure plasma jet (APPJ). Variation in the argon (Ar) gas flow rate influenced the spatial distribution of the hydroxyl radicals (∙OH) as it altered the laminar-to-turbulent flow transition. The highest density of ∙OH was recorded to be 3.1 × 1016 cm−3 when the Ar flow rate was maintained at 2 standard liters per minute. Additionally, the ∙OH concentration in plasma-activated water substantially increased to 35.5 μM with prolonged treatment. Similarly, the concentrations of H2O2, which is formed as a result of the recombination of the ∙OH, gradually increased to 34.4 μM over 8 min of treatment time, and subsequently reduced to 32.6 μM after an additional 2 min of treatment. A degradation rate of 96.6 % was achieved within 10 min of treatment, as confirmed by a gas chromatography (GC)-flame ionization detector. GC-mass spectrometry was used to identify the intermediate products, and propose possible degradation pathways. However, a decline in the energy efficiency was observed because of reduced initial concentration over the extended treatment time. Furthermore, a 40 % increase in cell viability and a 45 % decrease in the percentage of the dead cell population were observed during the exposure of MRC5, astrocytes, and PC-3 cell lines to APPJ-treated DBP solution, indicating reduced toxicity of the contaminant. Thus, the proposed approach can effectively reduce the contamination of water resources by DBP.

Comparing the Effects of Different Dielectric Materials on an Atmospheric Pressure Plasma Jet by Experiments and Simulations

ABSTRACTThis study investigates how quartz and alumina affect atmospheric pressure plasma jet (APPJ) stability using numerical simulations and experiments. Unlike previous research, it uses simulations and equivalent circuits to explore discharge characteristics. Experimental results show a temperature increase in quartz APPJ, leading to decreased gas voltage and enhanced plasma intensity, validated by equivalent circuit analysis. Alumina APPJ maintains more stable plasma intensity. Simulation reveals that higher dielectric coefficients enhance capacitance, leading to higher plasma parameters such as electron density, ion density, and electron temperature. This research clarifies quartz's voltage increase over time, which is crucial for biomedical plasma applications, aiding in selection of stable dielectric materials.

A new optimization strategy, the influence of hollow electrode chamfers on the development of helium atmospheric pressure plasma jets

This work suggests applying chamfering treatment to the plasma generator of the empty electrode structure. Enhancing the electrodes’ physical structure can significantly improve plasma characteristics without requiring intricate control systems. Experiments have shown that changes in the electrode’s shape can lead to changes in the formation of the atmospheric pressure plasma jet. Specifically, our observations indicate that an increase in the chamfer radius leads to an increase in the ignition voltage and a greater density of reactive species inside the jet. We developed a multi-channel equivalent circuit model to describe the discharge process of a plasma jet. Then, using the mixed layer theory, we investigated the effect of the chamfer radius on the plasma jet. Our findings suggest that chamfering increases the effective discharge area, resulting in more discharge channels in the model. This leads to a higher density of reactive species. Additionally, chamfering improves the mixing of helium and air, increasing the concentration of N2 and O2. This consumes some of the avalanche electrons and raises the ignition voltages, ultimately enhancing the chemical reactivity of the plasma jet. This work provides new ideas for the optimization strategy of atmospheric pressure plasma radiation devices.

Physicochemical properties and antimicrobial efficacy of argon cold atmospheric pressure plasma jet activated liquids – a comparative study

Cold atmospheric pressure plasma jet activated liquids (CAPJALs) have attracted considerable scientific attention due to their peculiar antimicrobial characteristics. In the current context, there is a need to compare the bactericidal activity of CAPJALs and demonstrate the specific parameters necessary to obtain greater effectiveness. This in-vitro research examines the antimicrobial activity of liquids, such as deionized water (DI-W), drinking water (DW), tap water (TW), and normal saline (NS) activated by Ar cold atmospheric pressure plasma jet (CAPJ) against multidrug-resistant (MDR) E. coli and S. aureus. The computed D- value showed that CAPJALs' bacterial inactivation efficacy followed the trend – DI-W ≈ NS > DW > TW for both the isolates. To obtain greater bactericidal effectiveness, an optimum combination of liquid activation time by CAPJ and CAPJAL – bacteria interaction time was noticed. In addition, the rate at which the physicochemical parameters (pH, electrical conductivity (EC), total dissolved solids (TDS), and concentration of reactive species (H2O2, NO3-, and NO2-)) changed within the liquid varied in different ways. It was observed that the identified gas-phase species (Ar I, Ar+, N2, N2+, O I, OH•, OH+, NO+, O2+, N2O3-, NO3-, N2O2-, etc.) would contribute to modification of liquid physicochemical property by generating liquid phase reactive species (NO3-, NO2-, H+, H2O2, ONOOH, Cl2, HOCl, etc.) via reaction cascades. These reactive species in the liquid phase, together with other physicochemical characteristics, were found to play a part in the process of bacterial inactivation. This study into the underlying mechanism of CAPJ – liquid and CAPJAL – bacteria interaction would help to determine its potential use as a disinfectant in healthcare settings. List of microorganismsE. coli: Escherichia coli; S. aureus: Staphylococcus aureus.

Enhanced Oxygen Evolution Reaction Performance of NiMoO4/Carbon Paper Electrocatalysts in Anion Exchange Membrane Water Electrolysis by Atmospheric-Pressure Plasma Jet Treatment.

NiMoO4 was grown on carbon paper (CP) by a hydrothermal method. A rapid and high-temperature atmospheric-pressure plasma jet (APPJ) process was used to generate more oxygen-deficient NiMoO4 on the CP surface to serve as an electrode material for the oxygen evolution reaction (OER). After 60 s of APPJ treatment, the overpotential of the electrode at 100 mA/cm2 decreased to 790 mV and that at 10 mA/cm2 decreased to 368 mV. Additionally, the charge transfer resistance decreased from 2.8 to 1.2 Ω, indicating that APPJ treatment effectively reduced the electrode overpotential and impedance. The effect of NiMoO4/CP/APPJ-60 s on the anion exchange membrane water electrolysis (AEMWE) system was also tested. At a system temperature of 70 °C and current density of 100 mA/cm2, the energy efficiency reached 95.1%, and the specific energy consumption decreased from 4.02 to 3.83 kWh/m3. These results demonstrate that the APPJ-treated NiMoO4/CP electrode can effectively enhance the OER performance in water electrolysis and improve the energy efficiency of the AEMWE system. This approach shows promise in replacing precious metal electrodes, thereby potentially reducing the cost and providing an environmentally friendly alternative.

Mechanism of lipid peroxidation of liposomes by cold atmospheric pressure plasma jet irradiation.

Liposome lipid peroxidation induced by cold atmospheric pressure plasma jet (CAPPJ) irradiation was investigated. The formation of thiobarbituric acid reactive substances (TBARS), an indicator of lipid peroxidation final products, as a function of irradiation was observed. Lipid radicals, peroxidation reaction intermediates generated by CAPPJ irradiation, were confirmed by increased NBD-pen fluorescence intensity. Additionally, lipid peroxidation products, liposomal phosphatidylcholine (PC) isomers, were analyzed by LC-MS/MS. Products specific to singlet oxygen (1O2) oxidation, 16:0/10-hydroperoxy-8E,12Z-octadecanoic acid (10-8E,12Z-HpODE) PC and 16:0/12-9E,13E-HpODE PC, were not detected, but radical oxidation specific products 16:0/13-9E,11E-HpODE PC and 16:0/9-10E,12E-HpODE PC were. This suggests that during CAPPJ irradiation, radicals, rather than 1O2, are the primary reactive species of lipid peroxidation. This is also supported by the β-carotene quenching of 1O2 not suppressing TBARS and lipid radical generation. Also, neither TBARS formation nor lipid radical generation were suppressed by SOD, indicating that the superoxide radical (O2 •-) is not responsible for the lipid peroxidation reaction. As the CAPPJ irradiation of water produces large quantities of hydroxyl radical (•OH) and •OH scavengers decreased the amount of TBARS produced by CAPPJ irradiation, it is highly plausible that •OH is the primary species involved in CAPPJ-induced liposome lipid peroxidation.

Energy efficiency of reactive species generation in radio frequency atmospheric pressure plasma jets driven by tailored voltage waveforms in a He/O2 mixture

Abstract The effect of the shape of the applied voltage waveform on the energy efficiency of reactive species generation is investigated in an atmospheric pressure RF microplasma jet operated in a He/O2 mixture (99.5%/0.5%) based on a one-dimensional hybrid fluid-kinetic simulation method. Using a tailored waveform synthesized from four consecutive harmonics (with a base frequency of f b = 13.56 MHz and amplitudes of ( 160 / k ) V for the k-th harmonic), it is shown that by changing the identical phases of the even harmonics in the waveform, ϕ, the generation efficiencies of three specific reactive species (helium metastables, atomic and vibrationally excited oxygen), defined as the ratio of mean density and input plasma power, attain their maxima for different values of ϕ, due to changes in the Electron Energy Probability Function (EEPF). The phase control of the EEPF and its critical role in modulating generation energy efficiencies are explained in detail. The simulation results are verified by experimental (Phase Resolved Optical Emission Spectroscopy and Two Photon Absorption Laser Induced Fluorescence) data.

Improving insulating film deposition stability with atmospheric pressure plasma jet by post-mixing precursor feedthrough with hollow electrode

Film deposition with atmospheric pressure plasma jet (APPJ) is an effective approach to enhance surface performances of insulating materials for its high reactivity and flexible operation. However, the plasma-activated precursor will inevitably produce inner-wall contamination in the dielectric tube as it travels through the electrode gap, deteriorating film deposition stability during long-term operation. In this paper, a post-mixing precursor feedthrough is designed to suppress the dielectric tube contamination and improve film deposition stability. The influences of traditional pre-mixing feedthrough and post-mixing feedthrough proposed in this paper on discharge and film deposition stability are compared. The thickness of inner-wall contamination is acquired by image processing technique. The electrical and optical discharge characteristic variations with operation duration are diagnosed to evaluate the discharge stability. The film performance is characterized by the water contact angle (WCA) and flashover voltage. Finally, scanning electron microscope (SEM) and X-ray photoelectron spectroscopy (XPS) measurements are performed for the film physicochemical property variations to explore the mechanism about the effect of precursor feedthrough on film deposition stability. The results indicate that the thickness of the contamination is reduced by 79.9 % for the post-mixing feedthrough after a 30-minute operation. Contamination growth increases the initial discharge voltage and decreases the discharge strength, which is remarkably inhibited for the post-mixing feedthrough. The degradation of WCA and flashover voltage for the post-mixing feedthrough is <10 % after a 30-minute operation. The film physicochemical properties for the post-mixing feedthrough exhibit no spectacular change according to SEM and XPS results. Whereas, the ratio of high-oxidized silicone bonds for the pre-mixing feedthrough is reduced and the degree of cross-linking is drastically decreased. This paper provides a reference for optimizing precursor feedthrough to improve the stability of film deposition with APPJ.

Shrouding Gas Plasma Deposition Technique for Developing Low-Friction, Wear-Resistant WS2-Zn Thin Films on Unfilled PEEK: The Relationship Between Process and Coating Properties

In this study, tungsten disulfide–zinc (WS2-Zn) composite films were generated on polyether ether ketone (PEEK) disks by an atmospheric pressure plasma jet (APPJ) equipped with a shrouding attachment. The friction and wear properties of the WS2-Zn coatings were intensively investigated by using a rotational ball-on-disk setup under dry sliding and ambient room conditions. In order to gain more information about the lubrication mechanism, the coating areas as deposited and the worn areas (i.e., in the wear track) were analyzed with a scanning electron microscope (SEM) with regard to their chemical composition in depth by energy-dispersive X-ray spectroscopy (EDS). X-ray photoelectron spectroscopy (XPS) was conducted to obtain precise chemical information from the surface. The results indicated that WS2-Zn coatings significantly improved the tribological properties, exhibiting a coefficient of friction (COF) of &lt;0.2. However, the tribological performance of the coatings is strongly dependent on the plasma process settings (i.e., plasma current, dwell time of the powder particles in the plasma jet), which were tuned to reduce the oxidation by-products of WS2 to a minimum. The COF values achieved of the dry lubricant films were significantly reduced in contrast to the uncoated PEEK by a factor of four.

Cold Atmospheric Pressure Plasma May Prevent Oral Mucositis-Related Candidemia in Chemotherapy-Treated Rats.

Oral mucositis associated with candidiasis can causes systemic candidemia, posing a risk to cancer patients administered antineoplastic therapy. Cold atmospheric pressure plasma jets (CAPPJs) have antifungal and anti-inflammatory properties. This study evaluated the effects CAPPJs in preventing systemic fungal dissemination in a murine model of oral mucositis associated with candidiasis. Forty Wistar rats were divided into groups: CAPPJs (treated) and non-treated controls (for comparison), with subgroups subject to 24 and 72 h of treatment (n = 10 each). Four cycles of chemotherapy (cisplatin and 5-fluorouracil (5-FU)) were administered, followed by oral inoculation of Candida albicans for 3 days. Mucosal damage was induced on the lateral side of tongue with 50% acetic acid. CAPPJ treatment was performed on the lesion for 5 min (2 days). Body weight was assessed daily. Fungal dissemination was conducted using organ macerates and plated on Sabouraud Agar with chloramphenicol. Blood samples were obtained for blood count tests. Chemotherapy affected the general health of the animals, as evidenced by body weight loss. Treatment with CAPPJs showed an inhibitory effect on C. albicans, with a significant reduction in fungal recovery from the tongue after 24 h (p < 0.05). Interestingly, systemic fungal dissemination was significantly reduced after 24 and 72 h of treatment when compared to control (p < 0.05). Taken together, these results suggest that CAPPJs have potential for clinical application in patients with oral mucositis at risk of candidemia.

Characterization of modified low‐density polyethylene by cold atmospheric pressure plasma jet treatment in the melt state

AbstractCold plasma treatment in the melt state is a novel area of research focused on producing modified polymers, hence more research on the underlying plasma‐polymer interactions in this context is needed. In this study, low‐density polyethylene (LDPE) was treated with a cold atmospheric pressure plasma jet (CAPPJ) during melt processing in a polymer batch mixer. Electron spin resonance (ESR) results proved that plasma treatment effectively generates free radicals in the material, increasing the room temperature spin concentration by an order of magnitude to 2 × 1015 spins g−1. The generated radicals react mainly by cross‐linking, forming a gel phase of up to 31%, and consequently increasing the polymer's melt viscosity. Furthermore, oxidation was established as solely a thermal effect limited by radical availability at the interface exposed to the atmosphere, whereas plasma exposure did not lead to further oxidation. Interestingly, plasma appears to interact with the thermally created ketone groups, possibly forming unsaturated carbonyl compounds.

Influence of the water content in polyamide 6 on atmospheric pressure plasma jet pre-treatment and adhesion for adhesive bonding

AbstractTo quantify the influence of absorbed water in PA6 on the pre-treatment and bonding process, an unfilled and unreinforced PA6 material is investigated in a dried and saturated state. The material is pre-treated by atmospheric pressure plasma jet (APPJ) with varying jet distances. The surfaces are investigated by contact angle measurements, DSC and FTIR to detect molecular and morphological changes in the surface. To evaluate the bonding strength, samples are bonded with a two-component polyurethane adhesive and a two-component acrylate adhesive and tested in a lap shear and a tensile configuration. The results show that water content has a significant influence on the effectivity of the pre-treatment process and the resulting bonding strength and failure mechanism. The adhesion is majorly affected, however these effects do not influence the macroscopic wetting behavior and cannot be measured in contact angles. FTIR spectra and DSC scans do not show significant changes in molecular groups or crystallinity that would explain the observed adhesion improvement in dried samples. High bonding strength is only achieved with adherents at low water content.