Atmospheric Pressure Plasma Jet Treatment Research Articles

Surface cleaning with atmospheric pressure plasma jet investigated by in-situ optical emission spectroscopy and laser-induced breakdown spectroscopy

Cleaning of surfaces with atmospheric pressure plasma jet (APPJ) is investigated by in-situ optical emission spectroscopy (OES) and laser-induced breakdown spectroscopy (LIBS). The APPJ device operates a spark discharge of kW power in Argon gas flow resulting in a powerful plasma jet expanding into air. For cleaning experiments samples are coated with lubricant layers of 1.1 to 7.1 µm thickness. Light collected at the sample surface during APPJ treatment is analyzed spectroscopically and used to monitor the cleaning process. LIBS chemical imaging delivers spatial cleaning profiles of plasma treated surfaces. From measured emission intensities of CN molecular band and Na atomic line the cleaning efficiencies for carbon and Na containing contaminants are determined. The power of APPJ plasma generator, distance between sample and jet nozzle, scan speed, and Argon gas flow are varied to optimize the surface treatment. Thermal and non-thermal processes contribute to cleaning. For the carbon containing contaminant thermal processes are dominating (∼90 %) while also non-thermal processes (∼30–45 %) are relevant for the Na containing component. A cleaned surface area per time from 0.3 to 10 cm2/s is investigated. Cleaning efficiency up to 95 % is obtained highlighting the potential of APPJ surface cleaning under ambient conditions.

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.

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.

The oxidative stress mechanism of Bacillus cereus spores induced by atmospheric pressure plasma jet

Emerging plasma technology has demonstrated its effectiveness in inactivating bacteria and spores, showing wide applicability in environment cleaning and in the food supply chain. Studies have revealed that the main reason of plasma-mediated bacterial inactivation were contributed to the oxidative damage on inner membranes (IMs) of cell, while few research paid attention to the oxidation stress process of lipid in spores’ IMs. This study investigated the impact of atmospheric pressure plasma jet (APPJ) treatment on spore inactivation, focusing on oxidative stress mechanisms and changes in membrane lipid composition. Results demonstrated that APPJ treatment induced significant oxidative stress within spores, characterized by elevated levels of reactive oxygen and nitrogen species (RONS). This oxidative stress led to the peroxidation of glycerophospholipids, particularly phosphatidylglycerol, phosphatidylcholine, and cardiolipin, major components of spore membranes. Subsequently, the rearrangement of membrane lipid and the formation of lipid hydroperoxide, caused by the released cations and RONS, accelerated membrane instability. These changes correlated with increased membrane permeability and structural damage observed via flow cytometry, indicating the critical role of membrane lipid peroxidation in spore inactivation. Furthermore, the study highlighted the potential of APPJ as a robust technology for enhancing food safety by targeting spore-forming pathogens throughout the food supply chain.

Research on Solid-State Linear Transformer Driver Power Source Driving Atmospheric Pressure Plasma Jet Treatment of Epoxy Resin

The Solid-State Linear Transformer Driver (SSLTD) is a nanosecond pulse power source characterized by its fast rise time and adjustable output waveform. It can generate uniform and stable atmospheric plasma jets, which is suitable for material surface modification. In this study, a 15-stage SSLTD was designed and assembled, which can produce a stable nanosecond pulse voltage up to 15 times the amplitude of the charging voltage at high frequencies, with a rise time of approximately 10 ns. This device can be used to generate stable atmospheric pressure Ar plasma jets with an electron density in the range of 1015~1016 cm−3 and gas temperatures close to room temperature. After the modification treatment by the plasma jets, the content of the C=O groups on the surface of the epoxy resin significantly increased in the wavelength range of 1720~1740 cm−1, and its flashover resistance was noticeably enhanced. The optimal comprehensive modification effect was achieved at a charging voltage of 600 V, pulse width of 50 ns, and pulse frequency in the range of 800~1000 Hz.

Effects of cold atmospheric plasma‐treated medium on HaCaT and HUVEC cells in vitro

AbstractCold atmospheric plasma (CAP) is an emerging technology that can generate various reactive oxygen and nitrogen species (RONS) at room temperature and shows promising applications for skin wound healing. The effects of plasma‐treated medium (PTM) promoting cell proliferation have been verified, but the biological mechanisms involved are not well known. This study aims to assess the proliferation effect and mechanism induced by PTM on human keratinocyte cells (HaCaT) and human umbilical vein endothelial cells (HUVEC) in vitro. The results showed that the concentrations of H2O2 and NO2− inside PTM increased in a time‐dependent manner as the atmospheric pressure plasma jet (APPJ) treatment time was prolonged. The biological outcomes were determined by cell counting kit, wound healing assay, flow cytometry, enzyme‐linked immunosorbent assay (ELISA), and western blot analysis. The cell viability and motility assays indicated that appropriate plasma conditions of short treatment time (15s‐, 30s‐ and 45s‐PTM) could promote cell proliferation, while long treatment time would inhibit cell proliferation (60s‐PTM). With an appropriate time of PTM treatment, the secretion of vascular endothelial growth factor‐α (VEGF‐α) and transforming growth factor alpha (TGF‐α) was promoted and the extracellular signal‐regulated kinase/serine‐threonine protein kinase pathways were activated, which induced HaCaT and HUVEC cell proliferation eventually. These behaviors of cells were mainly related to the enhancement of intracellular reactive oxygen species levels. These findings established a theoretical foundation for potential clinical applications of PTM in wound healing.

Influence of O2 content on surface modification of epoxy resin using He/CF4 atmospheric pressure plasma jet to improve surface flashover strength

In order to improve the surface flashover strength of the insulation materials and solve the problem that the relatively high price of CF4 restricts the large-scale application of fluorination modification of CF4 atmospheric pressure plasma jet (APPJ) in the industrial field, He/CF4/O2 APPJ with different O2 content is used to treat epoxy resin (EP) dielectric material. By analyzing the results of scanning electron microscopy, atomic force microscopy, and x-ray photoelectron spectroscopy, the influence of O2 content on the multiple characteristics of EP surface before and after APPJ treatment is studied. Flashover experiment is also carried out on EP surface before and after APPJ treatment. It is found that the addition of 0.1% O2 can increase the mature voltage of the EP surface by about 16.10% compared with untreated EP surface. It is concluded that the improvement of the surface flashover strength with a small amount of O2 (within 0.1%) is influenced by the surface roughness and chemical composition of the dielectric. The deposition effect of APPJ on EP surface is enhanced to increase the surface roughness and reaches the best at 0.1% O2, because the addition of excessive O2 will weaken the APPJ intensity. It is speculated that the creepage distance of the EP surface is increased to inhibit the formation of electron collapse and the content of electronegative fluorine and oxygen on the EP surface is increased under a small amount of O2 addition, resulting in the inhibition of the formation of surface flashover.

Direct Current Pulse Atmospheric Pressure Plasma Jet Treatment on Electrochemically Deposited NiFe/Carbon Paper and Its Potential Application in an Anion-Exchange Membrane Water Electrolyzer.

An atmospheric pressure plasma jet (APPJ) is used to process electrochemically deposited NiFe on carbon paper (NiFe/CP). The reactive oxygen and nitrogen species (RONs) of the APPJ modify the surface properties, chemical bonding types, and oxidation states of the material at the self-sustained temperature of the APPJ. The APPJ treatment further enhances the hydrophilicity and creates a higher disorder level in the carbon material. Moreover, the metal carbide bonds of NiFe/CP formed in the electrochemical deposition (ED) process are converted to metal oxide bonds after APPJ processing. The potential application of APPJ treatment on NiFe/CP in alkaline water electrolysis is demonstrated. With more oxygen-containing species and better hydrophilicity after APPJ treatment, APPJ-treated NiFe/CP is applied as the electrocatalyst for the oxygen evolution reaction (OER) in alkaline water electrolysis. APPJ-treated NiFe/CP is also used in a custom-made anion-exchange membrane water electrolyzer (AEMWE); this should contribute toward realizing the practical large-scale application of AEM for hydrogen production.

The Conversion of Li2SnO3 Li-Ion Hybrid Supercapacitors from Pastes Containing LiCl-SnCl2 Liquid Precursors Using an Atmospheric-Pressure Plasma Jet

We fabricate lithium tin-based oxide Li2SnO3 on carbon cloth from a gel-state precursor containing LiCl and SnCl2·2H2O using a nitrogen atmospheric-pressure plasma jet (APPJ). APPJ treatment provides both a high-temperature environment for the conversion of precursor into Li2SnO3 and nitrogen plasma reactive species for electrode surface modification. Here, the best electrochemical performance for the Li2SnO3 Li-ion hybrid supercapacitors (Li–HSCs) is achieved with 480 s of APPJ processing. The areal capacity of the 480 s APPJ-processed Li2SnO3 Li–HSCs reached 46.113 mC/cm2. The results indicate that APPJ is an effective tool for the rapid conversion processing of Li2SnO3 electrodes for Li–HSCs.

Pea protein-inulin conjugate prepared by atmospheric pressure plasma jet combined with glycosylation: structure and emulsifying properties.

Pea protein is one of plant proteins with high nutritional value, but its lower solubility and poor emulsifying properties limit its application in food industry. Based on wet-heating glycosylation of pea protein and inulin, effects of discharge power of atmospheric pressure plasma jet (APPJ) on structure, solubility, and emulsifying ability of pea protein-inulin glycosylation conjugate were explored. Results indicated that the APPJ discharge power did not affect the primary structure of pea protein. However, changes in secondary and spatial structure of pea protein were observed. When APPJ discharge power was 600 W, the solubility of glycosylation conjugate was 75.0% and the emulsifying stability index was 98.9 min, which increased by 14.85 and 21.95% than that of only glycosylation sample, respectively. These findings could provide technical support for APPJ treatment combination with glycosylation to enhance the physicochemical properties of plant-based proteins.

Effect of atmospheric pressure plasma jet on the structure and physicochemical properties of wheat starch.

The effect of atmospheric pressure plasma jet (APPJ) with different discharge power (0, 400, 600, and 800 W) on the structure and physicochemical properties of wheat starch were evaluated in this study. After APPJ treatments, significant declines in peak viscosity, breakdown viscosity, and final viscosity of wheat starch pasting parameters were observed with increase of plasma treatment power. Being treated with discharge power of 800 W, the PV and BD value of wheat starch paste significantly dropped to 2,578 and 331 cP, respectively. Apparently, APPJ could raise the solubility of wheat starch, while reduce the swelling capacity, and also lower the G' and G″ value of wheat starch gel. Roughness and apparent scratch was observed on the surface of the treated wheat starch granules. Although APPJ treatment did not alter wheat starch's crystallization type, it abated the relative crystallinity. APPJ treatment might be useful in producing modified wheat starch with lower viscosity and higher solubility.

Effect of atmospheric pressure plasma jet treatment on the performance of needleless electrostatic spinning with low concentration of PCL solution

PCL nanofibers were prepared by needle-free electrostatic spinning using atmospheric atmospheric pressure plasma to pretreat Polycaprolactone (PCL) electrostatic spinning solution. The results show that the conductivity and acidity of the plasma-treated polymer solution increase significantly, and the viscosity increases and then decreases. The untreated and treated solutions were then subjected to electrostatic spinning, and it was found by scanning electron microscopy that the solutions obtained after plasma treatment had fewer beads on the surface of the fibers, and the nanofibers were more uniformly distributed in diameter and finer. It was also found that the plasma treatment affected the size of the molecular chain segments of the PCL, and the crystal structure of the fibers was altered.The XPS results showed that the surface elements of the nanofibers do not change before and after the plasma treatment, and the chemical bonding between the carbon and oxygen elements is consistent.

Surface Modification on TiNb2O7 Anode Via Atmospheric Pressure Plasma Jet for High-Rate Lithium-Ion Battery

Lithium-ion battery is one of the most vital energy storage devices due to high energy density property. In anode, TiNb2O7 (TNO) demonstrates high capacity as compared to Li4Ti5O12 materials. It is attractive for its high safety because of adequate Fermi level, implying that the solid electrolyte interface would not form during the charging and discharging process. This work provides a promising method of modifying the electrode, which includes PVdF, conductive carbon, and TNO, using the technology of atmospheric pressure plasma jet (APPj) treatment. This method is potential to accomplish roll-to-roll modification in the industry without any complex synthesis processes. In addition, APPj method is a time-effective process to treat the electrode. It has found that the treatment via APPj enhances the electrochemical performance by N-doped decoration on conductive carbon, as well as defects manufacturing of the TNO anode materials, and electrolyte wettability improvement on binder. The surface free energy of the APP-20 sample increases, improving the wettability of the electrolyte and contributing to an enhanced electrochemical performance. The C-rate performance of APP-20 improves significantly at 10C as compared to the sample without treatment. Also, the cycle test of APP-10 provides high retention after 300 cycles at 1C. In summary, this work promotes a feasible and facile treatment for roll-to-roll processing, and the mechanism could be established. APPj In short, the modification technique of APPj is an affordable method to apply in the lithium-ion battery of the industry manufacturing.

Atmospheric plasma treatment: an alternative of HF etching in lithium disilicate glass-ceramic cementation.

Objectives: This study aimed to investigate whether the atmospheric pressure plasma jet (APPJ) could modify the surface of lithium disilicate glass ceramics (LDC) instead of hydrofluoric acid (HF) in LDC resin cementation. Methods: Two hundred and thirty-two LDC blocks were randomly divided into seven groups: Group 1 (16 specimens) was the blank control group (without HF or APPJ treatment); Group 2 (36 specimens) was etched by HF; Groups 3-7 (36 specimens each) were treated with APPJ, and the relative air humidity (RAH) of the discharge was 22.8%, 43.6%, 59.4%, 75.2%, and 94.0%, respectively. Three LDC blocks in each group were characterized via X-ray photoemission spectroscopy (XPS) analyses, 3 blocks via contact angle measurements, and other 10 blocks via surface roughness measurements. The residual LDC blocks in groups 2-7 were cemented to composite cylinders. Testing the cemented specimens' shear bond strength (SBS) before and after thermocycling (6,500 cycles of 5°C and 55°C) revealed fracture patterns. Data were analyzed by ANOVA (post hoc: Bonferroni) (α = 0.05). Results: After APPJ treatment, the water contact angle values of APPJ treated blocks dropped from 31.37° to 5.66°, while that of HF etched ones dropped to 18.33°. The O/C ratio increased after HF etching or APPJ treatment according to the calculated results, except for the APPJ-treated samples at a RAH of 22.8%. The surface roughness of LDC blocks showed no statistic difference before and after APPJ treatment, but experienced significant difference after HF etching. The O/Si and O/C ratios varied after HF etching or APPJ treatment. No significant difference in SBS values could be found among groups 2-7 before or after artificial aging (p > 0.05). All specimens showed mixed failure patterns. Conclusion: The APPJ treatment method reported in this study is a promising novel strategy for surface modification of the LDC. With acceptable bonding strength, it might be an alternative to HF in LDC-resin cementation.

Effect of Atmospheric Pressure Plasma Jet Treatments on Magnesium Phosphate Cements: Performance, Characterization, and Applications.

Atmospheric pressure plasma treatments are nowadays gaining importance to improve the performance of biomaterials in the orthopedic field. Among those, magnesium phosphate-based cements (MPCs) have recently shown attractive features as bone repair materials. The effect of plasma treatments on such cements, which has not been investigated so far, could represent an innovative strategy to modify MPCs' physicochemical properties and to tune their interaction with cells. MPCs were prepared and treated for 5, 7.5, and 10 min with a cold atmospheric pressure plasma jet. The reactive nitrogen and oxygen species formed during the treatment were characterized. The surfaces of MPCs were studied in terms of the phase composition, morphology, and topography. After a preliminary test in simulated body fluid, the proliferation, adhesion, and osteogenic differentiation of human mesenchymal cells on MPCs were assessed. Plasma treatments induce modifications in the relative amounts of struvite, newberyite, and farringtonite on the surfaces on MPCs in a time-dependent fashion. Nonetheless, all investigated scaffolds show a good biocompatibility and cell adhesion, also supporting osteogenic differentiation of mesenchymal cells.

Surface preparation of aluminum by atmospheric-pressure plasma jet for suspension plasma sprayed ceramic coatings

Surface preparation is a key step preceding the deposition of suspension plasma spray (SPS) coatings, a type of thermal spray coatings. This work evaluates the effect of surface preparation by atmospheric-pressure plasma jet (APPJ) treatment on the adhesion of SPS-deposited Al2O3 ceramic coatings on aluminum (Al-2024) substrates. For comparison, the substrate surfaces were also prepared by grit-blasting. Surface roughness (R) parameters and surface morphology of both grit-blasted and APPJ-treated substrates were characterized by confocal microscopy and scanning electron microscopy (SEM). In addition, surface chemistry was evaluated by attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR). Based on morphological analyses, the grit-blasted surfaces exhibit typical random peaks and valleys, whereas those subjected to APPJ treatment show self-organized patterns with multilayered and multiscale features. ATR-FTIR spectroscopy analyses also demonstrated a significant difference in surface chemistry for both surface preparation types. After the characterization of both types of prepared substrates, SPS coating was deposited on the substrates under two spray conditions. One spray condition demonstrated poor adherence of the coatings for both types of the prepared substrates; the other spray condition produced coatings with good adherence. The microstructures of the coating were evaluated for both spray conditions. The Adhesion strength of the coating was evaluated for the condition, which produced a coating with good adhesion. ASTM-C-633 pull test protocol was followed for the adhesion evaluation, and the pull test revealed significant adhesion improvements when the surface was prepared by APPJ. Improved adhesion strength was linked to the surface morphology and also to the surface chemistry of the surface prepared by APPJ. In addition, splat morphology was investigated on both grit-blasted and APPJ-treated substrates to correlate the improved adhesion.

Changes in physicochemical and conformational properties of myofibrillar proteins isolated from mandarin fish (Siniperca chuatsi) treated by atmospheric pressure plasma jet

ABSTRACT The effects of atmospheric pressure plasma jet (APPJ) treatment on the physicochemical and conformational properties of myofibrillar protein (MP) isolated from mandarin fish. The findings revealed that after exposing MP to APPJ for 0–12 s, there was a significant (P < .05) decline in the solubility and total sulfhydryl concentration. Turbidity and surface hydrophobicity increased significantly, while pH value decreased significantly at first but then stabilized. Gel electrophoresis confirmed that the extracted protein was unaffected. FTIR spectroscopy indicated that the APPJ treatment caused slight changes in secondary structure. However, the UV absorption spectral and intrinsic tryptophan fluorescence demonstrated that the tertiary structure of MP was altered following APPJ treatment. According to the rheological characteristics, APPJ treatment could improve protein cross-linking, raise storage modulus, and promote the development of protein gel network structure. These findings demonstrated that APPJ treatment might improve the functional characteristics of MP isolated from mandarin fish.

Influence of atmospheric pressure plasma jet on the structural, functional and digestive properties of chickpea protein isolate

Chickpea protein (CPI) is a promising dietary protein and potential substitute for soy protein in food product development due to its high protein content and low allergenicity. However, CPI possesses denser tertiary and quaternary structures and contains certain amount of anti-nutritional factors, both of which constrain its functional properties and digestibility. The objective of this study was to assess the effectiveness of atmospheric pressure plasma jets (APPJ) as a non-thermal method for enhancing the functional characteristics and digestibility of CPI. In this study, the reactive oxygen and nitrogen species generated by the APPJ treatment led to protein oxidation and increased carbonyl and di-tyrosine contents. At the same time, the secondary, tertiary and microstructural structures of CPI were changed. The solubility, water holding capacity, fat absorption capacity, emulsifying capacity and foaming capacity of CPI were significantly improved after 30 s APPJ treatment, and a higher storage modulus in rheology was observed. Additionally, it was observed that the in vitro protein digestibility (IVPD) of APPJ-treated CPI increased significantly from 44.85 ± 0.6 % to 50.2 ± 0.59 % following in vitro simulated gastric and intestinal digestion, marking a noteworthy improvement of 11.93 %. These findings indicate that APPJ processing can enhance the functional and digestive properties of CPI through structural modification and expand its potential applications within the food industry.

Li-Ni Metal Oxides Processed with Rapid Atmospheric-Pressure-Plasma Jet for Flexible Gel-Electrolyte Li-Ion Hybrid Supercapacitors

We use screen printing to deposit LiCl + Ni(NO3)2·6H2O pastes on a flexible carbon cloth substrate and then calcine it using a nitrogen atmospheric-pressure-plasma jet (APPJ). Through the high-temperature treatment by APPJ, pastes can be rapidly converted into Li-Ni oxides (LNOs). The LNOs on carbon cloth are then used as the electrodes of flexible gel-electrolyte Li-ion hybrid supercapacitors (Li-ion HSCs). The best areal capacity of 21.076 mC cm−2, as measured by cyclic voltammetry, is achieved by APPJ treatment at 620 °C for 480 s. To demonstrate the flexibility of the Li-ion HSCs, the Li-ion HSCs were bent at different curvatures to measure its performance. After bending test, the capacity remains >93% under bending with a curvature of up to 2 cm−1.

Tuning lattice defects and photocurrent response of ZnO thin films by Mg doping and Ar-H2 atmospheric plasma treatment

The effects of Mg doping and Ar-H2 atmospheric pressure plasma jet (APPJ) treatment on zinc oxide (ZnO) thin films were investigated. Mg doping has been demonstrated to facilitate the incorporation of atomic hydrogen in the ZnO lattice via Ar-H2 APPJ. The co-doping of Mg and H changed ZnO’s primary oxygen defect type from vacancy (VO) to interstitial (Oi), which reduced photocorrosion significantly. The dominance of interstitial defects (i.e., Zni and Oi) in the H-doped Zn0.9Mg0.1O thin film was confirmed by photoluminescence spectroscopy. Zni shallow donors improved light absorption at wavelengths > 650 nm, increasing the film’s photocurrent density. Without Mg, doping H via Ar-H2 APPJ was ineffective for pure ZnO thin film. The dominance of VO in pure ZnO thin film after APPJ, though enhanced light absorbance, gave rise to an erratic photocurrent response due to the instability of VO. The lack of acceptor states also led to severe photocorrosion.