Air Plasma Exposure Research Articles

Optimizing beet seed germination via dielectric barrier discharge plasma parameters

This study explores the synergistic effects of gas composition and electric field modulation on beetroot seed germination using dielectric barrier discharge (DBD) plasma. The investigation initially focuses on the impact of air plasma exposure on germination parameters, varying both voltage and treatment duration. Subsequently, the study examines how different gas compositions (argon, nitrogen, oxygen, and carbon dioxide) affect germination outcomes under optimal air plasma conditions. Results indicate that plasma treatment significantly enhances germination rates and seedling growth relative to untreated controls. Notably, plasma exposure alters seed surface morphology and chemistry, increasing roughness, porosity, and hydrophilicity due to the formation of new polar functional groups. The highest germination rate (a 54.84 % increase) and germination index (a 40.11 % increase) were observed at the lowest voltage and shortest duration, whereas higher voltages and prolonged exposure reduced germination, likely due to oxidative stress. Among the tested gas environments, air plasma was most effective in enhancing water uptake and electrical conductivity, while oxygen plasma resulted in the highest germination index and marked improvements in root and shoot length. Conversely, carbon dioxide plasma treatment exhibited inhibitory effects on both germination and subsequent growth metrics. The results highlight the potential of DBD plasma technology to enhance agricultural productivity by optimizing seed germination and early growth. The study emphasizes the importance of precise parameter tuning, particularly gas composition and plasma exposure conditions, to maximize benefits while minimizing adverse effects, offering a refined approach to seed priming in agricultural practices.

Silicon (100) surface passivation-driven tuning of Ag film crystallinity and its impact on the performance of Ag/n-Si mid-infrared Schottky photodetector

The utilization of metal/semiconductor Schottky devices for plasmonic harvesting of hot carriers holds immense potential in the field of sub-bandgap photodetection. In this work, we explore a surface passivation scheme using air plasma exposure to modify the Si (100) surface and subsequently the crystal orientation of the deposited Ag film for photon detection in the mid-infrared (MIR) regime. This tailoring was achieved by varying the plasma exposure duration (0, 150, 300, 450, and 600 s). As a result, we could tune the crystal orientation of Ag from the (200) to the (210) crystal plane, with the Ag (111) orientation present in all devices. Furthermore, the photo-response behavior under MIR exposure at λ = 4.2 µm was studied both experimentally and using COMSOL simulations. It was observed that both photoelectric (PE) and photothermal (PT) effects contributed to the photo-response behavior of all devices. The Ag/Si device exposed to air plasma for 300 s exhibited the maximum PE-driven response (2.73 µA/W), while the device exposed to air plasma for 600 s showed a significant PT-driven response (13.01 µA/W). In addition, this strategy helped reduce the reverse leakage current by up to 99.5%. This study demonstrates that MIR detection at longer wavelengths can be optimized by tailoring the crystal orientation of the metal film.

Surface modification of clay‐coated paper by atmospheric‐pressure plasma in air

The aim of this work was the wettability improvement of clay‐coated paper by ambient air plasma exposure. Industrial corona with a volume dielectric barrier discharge in cylindrical configuration was used as a plasma source; the exposure times varied from 0.25 up to 5 s. Water contact angle (WCA) measurement and surface free energy (SFE) evaluation were carried out for the estimation of wettability changes. Plasma treatment in the duration of 0.25 s was sufficient to decrease the WCA almost to the half of the original value, which was 76°. SFE of paper has increased by 40%–50% after plasma treatment. Long‐term ageing effect study of treated samples was carried out up to 3 months after the treatment. WCA did not reach the original value even after 3 months, and it was still 20%–30% lower. O/C ratio increased from 0.7 to 1.8 in case of 5‐s plasma treatment, and the new chemical bonds (C=O, O–C=O) were created on the surface.

Quantitative characterization of plasma treated PDMS microfluidic substrates by inverse gas chromatography

Abstract The effect of air plasma exposure time on the surface energies and acid-base characteristics of polydimethylsiloxane (PDMS) particles was studied. Polymerized PDMS powder was radio frequency induced air plasma irradiated for 2–10 s with the power of 500 W. The efficiency of the plasma treatments was investigated by a new generation inverse gas chromatograph, a surface energy analyzer. The dispersive component of surface energy was determined by the Dorris-Gray method describing the van der Waals interactions, while the specific component of surface energy expressed the surface ability for Lewis acid-base interactions. It was demonstrated that the air plasma treatment did not affect the dispersive and acidic parts of the surface energy and the change of surface hydrophilicity was caused by the raise of the electron-donor ability of the PDMS surface, characterized by van Oss-Good-Chaudhury’s base number. The optimal plasma treatment time was found to be 5 s. Analysis of the specific surface energy and acid-base characteristics with respect to exposure time showed that partial to complete hydrophobic recovery occurred within 38 h.

Sub-100 nm wrinkling of polydimethylsiloxane by double frontal oxidation.

We demonstrate nanoscale wrinkling on polydimethylsiloxane (PDMS) at sub-100 nm length scales via a (double) frontal surface oxidation coupled with a mechanical compression. The kinetics of the glassy skin propagation is resolved by neutron and X-ray reflectivity, and atomic force microscopy, combined with mechanical wrinkling experiments to evaluate the resulting pattern formation. In conventional PDMS surface oxidation, the smallest wrinkling patterns attainable have an intrinsic lower wavelength limit due to the coupling of skin formation and front propagation at fixed strain εprestrain, whose maximum is, in turn, set by material failure. However, combining two different oxidative processes, ultra-violet ozonolysis followed by air plasma exposure, we break this limit by fabricating trilayer laminates with excellent interfacial properties and a sequence of moduli and layer thicknesses able to trivially reduce the surface topography to sub-100 nm dimensions. This method provides a powerful, yet simple, non-lithographic approach to extend surface patterning from visible to the deep UV range.

Effects of non-thermal atmospheric pressure air plasma exposure on SLA-treated implant in relation to cellular activity

Surface properties of titanium implants are known as important factors for successful osseointegration. The purpose of this research is to apply recently highlighted non-thermal atmospheric pressure plasma jet (NTAPPJ) on sand blast, large grit, acid etching(SLA) treated Titaniumi surface to improve the hydrophilicity and cellular response. The change in the chemical binding state of SLA-treated Ti before and after the NTAPPJ treatment were determined using field emission scanning electron icroscope, optical surface roughness system, X-ray photoelectron spectroscope, and water contact angle measuring system. MC3T3-E1 cells (murine osteoblastic cell line) attachments and proliferations were examined by the PrestoBlue reagent. This study found that the compressed air-based NTAPPJ treatment on SLA-treated Ti surface significantly increased the hydrophilicity and MC3T3-E1 cell attachments and proliferations. These results suggested that compressed air-based NTAPPJ treatment on the SLA-treated Ti surface had an effect on increasing attachments and proliferations of MC3T3-E1 cell for better osseointegration in

Surface analysis of poly(ethylene naphthalate) (PEN) films treated at atmospheric pressure using diffuse coplanar surface barrier discharge in air and in nitrogen

Surface modification of poly(ethylene naphthalate) (PEN) films by Diffuse Coplanar Surface Barrier Discharge (DCSBD) in ambient air and nitrogen at atmospheric pressure was studied at short plasma exposure times from 1 s up to 10 s. Chemical changes in the surface composition after the plasma treatments were studied using a high resolution XPS (X-ray Photoelectron Spectroscopy). The water contact angle was reduced from an initial value of 79° to values of 31° and 20° for the ambient air and nitrogen plasma treatments. After 3 days of storage in ambient air the contact angles were still about 50° and 40°, respectively. The polar component of surface energy was changed by the aging significantly less than the total surface energy. Despite the marked increase in the surface energy, the plasma treatment had no significant influence on the surface morphology.The surface modification in air plasma resulted in significant reduction the OC bond formation on the treated surface. The concentration of oxygen on PEN surface was increased from an initial value of 22 at.% up to 45 at.% already after 5 s air plasma exposure, and this oxygen concentration remained constant for longer plasma treatments. A small presence of nitrogen under 1.5 at.% from the air was also found after the treatments. The nitrogen plasma modified surface composition only by implanted nitrogen up to 5 at.% when the ratio of CO and C–O was not significantly changed. But some new bonds are also expected to be formed in a very low number only.

The nature of the defects generated from plasma exposure in pristine and ultraviolet-cured low-k organosilicate glass

Defects in low-k organosilicate glass produced during air and nitrogen plasma exposure were investigated. The defects, through the measurements of electron-spin resonance and Fourier-transform infrared spectroscopy, were found to be silicon-dangling bonds. Air-plasma exposure increases the defect concentrations by breaking silicon–hydrogen bonds. Nitrogen-plasma exposure as well as free-radical exposure has only a small influence on the bond breaking. It was also shown that ultraviolet curing improves the chemical-damage resistance of the dielectric.

Plasma/thermal-driven the rapid wettability transition on a copper surface

A simple and time-saving method to realize the reversible wettability transition is reported. Through a solution–immersion process followed by stearic acid modification, a superhydrophobic surface was prepared on the copper surface. After being treated by air-plasma exposure, the surface wettability was converted into superhydrophilicity. XPS analysis demonstrated that the incorporation of oxygen species by air-plasma activation accounted for the highly hydrophilic character of the surface. Upon annealing the plasma-treated surface in air, the non-oxidized alkyl chains were transferred to the surface for recovery the superhydrophobicity. It was found that the recovery was fast upon annealing at a relative high temperature. By the alternation of air-plasma treatment and annealing process, the rapid reversible wettability transition between superhydrophobic and superhydrophilic state was realized. The shortest processing time for a whole reversible wettability transition was 21min.

Ablation behavior of SiC fiber/carbon matrix composites under simulated atmospheric reentry conditions

Processing, mechanical properties, and ablation behavior of SiC fiber/carbon matrix composites for a thermal protection system material of a re-entry vehicle were examined. Orthogonal 3-D woven fabrics ( V f = 0.21, 0.21 and 0.02 for x, y, z directions) made of SiC fibers (Tyranno ZMI) were applied for reinforcement with a carbon matrix formed by polymer impregnation and pyrolysis (PIP) and/or chemical vapor infiltration (CVI). This SiC/CVI-C composite has high ultimate tensile strength of 415 MPa at 25 °C. Air plasma exposure in a plasma wind tunnel revealed no surface recession. The mass loss rate decreased over time. The SiC/C composites exhibit excellent oxidation resistance in high enthalpy plasma air for short durations.

Spores Survivability After Exposure to Low-Temperature Plasmas

To date, research on the inactivation of microorganisms by nonequilibrium atmospheric pressure plasmas has mainly been concerned by the killing efficiency and/or with the study of the roles played by various plasma agents (ultraviolet, radicals, ions, etc.) in the inactivation process. In this paper, the authors look at the problem from the cells' side. More specifically, the following questions are asked: What part of the spore structure plays a crucial role in its defense against the unfavorable plasma environment, and if the cells do survive plasma treatment, do they emerge the same or do they undergo some kind of noticeable changes? Although complete and comprehensive answers to these questions are not at the authors' grasp at this time, this paper presents convincing preliminary data that show that the integrity of the proteins of a spore's coat plays a major role in its survivability and that cells that survive air plasma exposure emerge with a changed metabolism

Tritium retention in CX-2002U and methods to reduce tritium inventory

Tritium retention in CX-2002U was studied by exposure to high flux of D/T atomized particles. The amount of tritium retained in CX-2002U appeared to be proportional to the half power of total incident fluence below 597 K and to the one third power at 897 K. No saturation was observed up to 10 27 atoms/m 2 at 297 K. The tritium concentration profile was also measured by means of autoradiography, from which an overall diffusion coefficient of D t =3.6×10 −14 m 2/s at room temperature was estimated. This value, which was much larger than the reported bulk diffusion coefficient, implies additional diffusion processes such as pore diffusion of tritium atoms or molecules. Tritium removal from the sample by exposure to air and helium plasma after irradiation of D/T atomized particles was studied. Tritium retention was reduced by about one tenth during air plasma exposure and by about a half during helium plasma exposure.