Pressure Glow Discharge Plasma Research Articles

Study of surface atmospheric pressure glow discharge plasma based on ultrathin laminated electrodes in air

A method to generate large-area surface plasma in air by micro-discharge is proposed. Two ultrathin laminated electrode structures of non-insulating and insulating types were formed by using the nanoscale ITO conductive layer. The surface glow discharge in atmospheric air is realized in low discharge voltage by constructing the special electric field of two-dimensional unidirectional attenuation. In particular, the insulating electrode structure can avoid the loss of ITO electrodes so that the discharge stability can be increased, and the treated objects can be prevented from metal ion pollution caused by the electrode in the discharge. It has broad application prospects in the fields of aerodynamics and material surface treatment.

Exploration to generate atmospheric pressure glow discharge plasma in air

Atmospheric pressure glow discharge (APGD) plasma in air has high application value. In this paper, the methods of generating APGD plasma in air are discussed, and the characteristics of dielectric barrier discharge (DBD) in non-uniform electric field are studied. It makes sure that APGD in air is formed by DBD in alternating current electric field with using the absorbing electron capacity of electret materials to provide initial electrons and to end the discharge progress. Through designing electric field to form two-dimensional space varying electric field and three-dimensional space varying electric field, the development of electron avalanches in air-gap is suppressed effectively and a large space of APGD plasma in air is generated. Further, through combining electrode structures, a large area of APGD plasma in air is generated. On the other hand, by using the method of increasing the density of initial electrons, millimeter-gap glow discharge in atmospheric pressure air is formed, and a maximum gap distance between electrodes is 8 mm. By using the APGD plasma surface treatment device composed of contact electrodes, the surface modification of high polymer materials such as aramid fiber and polyester are studied and good effect of modifications is obtained. The present paper provides references for the researchers of industrial applications of plasma.

The polypropylene membrane modified by an atmospheric pressure plasma jet as a separator for lithium-ion button battery

The plasma modification of the polypropylene (PP) membrane as a separator in lithium-ion battery (LIB) has been reported in this paper. Specifically, a commercial PP separator was modified by an atmospheric pressure glow discharge plasma jet (APGD-PJ) with the acrylic acid (AA) monomer. The morphology, electrolyte uptake and retention, the pore size distribution, and the electrochemical properties of the modified PP separator were analyzed. The experimental results indicate that the AA polymer (PAA) was uniformly coated on the surface of the PP membrane, and the contact angle of modified PP was reduced from 112° to 39° using He/O2/AA plasma and the electrolyte uptake of the modified PP separator increased to above 300% of the value of the unmodified one. Compared with the original PP, the cells assembled with the PP separator modified with Ar/O2/AA or He/O2/AA plasma showed higher capacities and better C-rate capacity. The excellent performances of assembled LIB endow the APDG-PJ as a promising protocol for modifying polyolefin separators for LIB applications.

Study on Glow Discharge in One-Dimensional Transverse Non-uniform Electric Field and Surface Processing of Aramid Fabric

Using a staggered contact electrode structure, the conditions for and mechanism of uniform discharge in one-dimensional transverse non-uniform electric field and with aramid fiber (AF) as a dielectric barrier material were explored for the first time in this study. An atmospheric pressure glow discharge (APGD) plasma was generated, and the large-area and continuous processing of AF was achieved. Through the electric field simulation as well as scanning electron microscope and X-ray photoelectron spectroscopy tests, it was found that the modification method of pressing the electrode closely to the AF could form the extremely strong electric field region of magnitude 1.444 × 107 V/m under the premise of uniform discharge. The highly active plasma generated could not only effectively increase the surface roughness of the treated material, but also introduce nitrogen functional groups which can’t be introduced through traditional air plasma. As found through the contact angle measurement, the contact angle was greatly decreased (by 52.3%) after being treated with 12.05 W/cm3 of plasma for 10 s, indicating that APGD plasma can achieve a good modification effect and high modification efficiency at low discharge power density.

Battery-Operated Atomic Emission Analyzer for Waterborne Arsenic Based on Atmospheric Pressure Glow Discharge Excitation Source.

In this paper, a sensitive atomic emission spectrometer (AES) based on a new low power and low argon consumption (<8 W, 100 mL min-1) miniature direct current (dc) atmospheric pressure glow discharge (APGD) plasma (3 mm × 5 mm) excitation source was developed for the determination of arsenic in water samples. In this method, arsenic in water was reduced to AsH3 by hydride generation (HG), which was then transported to the APGD source for excitation and detected by a compact CCD (charge-coupled device) microspectrometer. Different parameters affecting the APGD and the hydride generation reactions were investigated. The detection limit for arsenic with the proposed APGD-AES was 0.25 μg L-1, and the calibration curves were found to be linear up to 3 orders of magnitude. The proposed method was successfully applied to the determination of certified reference material (GBW08605), tap water, pond water, groundwater, and hot spring samples. Measurements from the APGD analyzer showed good agreement with the certified value/values obtained with well-established hydride generation atomic fluorescence spectrometry (HG-AFS). These results suggest that the developed robust, cost-effective, and fast analyzer can be used for field based arsenic determination and may provide an important tool for arsenic contamination and remediation programs.

Study of atmospheric-pressure glow discharge plasma jets based on analysis of electric field

To achieve an atmospheric-pressure glow discharge (APGD) in a long electrode gap and generate large-diameter atmospheric-pressure glow discharge plasma jets (APGDPJs), an electrode, adopting the mode of a dielectric barrier discharge with a non-uniform dielectric thickness, was used. For the analysis of the electric field profile of the electrode, the strong electric field areas that could easily generate discharge could initially be formed in the non-uniform gap. Additionally, the distribution of the electric field with high intensity in the short gap and low intensity in the long gap was not likely to result in a filament discharge. Experiments indicate that the electrode could not only achieve APGD in the discharge gap by using air and nitrogen, but also generate stable nitrogen APGDPJs with a diameter of 3.5 mm. This was a relatively large diameter achieved for a glow discharge nitrogen plasma jet device.

Surface Processing of Polyester Canvas using Atmospheric Pressure Air Glow Discharge Plasma

A staggered contact electrode structure was proposed in this study. Through pressing the electrode closely to the surface of polyester canvas, the electric field distribution with intensive electric field in short gap while weak electric field in long gap was formed, which was conducive to inhibit the emergence of filamentary discharge. Specifically, such electric field distribution could restrain the development degree of electron avalanche so that the quasi atmospheric pressure glow discharge plasma with nearly uniform luminescence could be generated in air gaps between the electrode and the surfaces of polyester canvas. Moreover, the device based on multi groups of staggered contact electrode structures was employed to achieve the large-area and continuous processing of polyester canvas. Through scanning electron microscope observations and peel strength tests, it could be observed that the surface roughness of polyester fabrics was obviously enhanced and the adhesion property of the canvas was greatly improved after treatment. The peel strength value was increased from 3.5 to 7.3 N/mm.

A study of the glow discharge plasma jet of the novel Hamburger-electrode

To generate atmospheric pressure glow discharge plasma jets (APGDPJs), a novel Hamburger-electrode was proposed. Through the study on electric field distributions, flow field distributions, and characteristics of the discharge and jet, we found that adopting the mode of dielectric barrier discharge with non-uniform thickness of dielectric, it was easy to form the strong electric field areas which were conducive to generate discharge and electric field distributions with large electric field intensity in the narrow gap and weak electric field intensity in the wide gap that were not inclined to form a filament discharge. Using the structure of evenly distributed inner electrodes, it was easy to weaken the pressure of strong electric field areas and form flow field distributions which is beneficial for taking out the high density charged particles and generating APGDPJs. Stable APGDPJs in nitrogen with 3.5 mm in diameter and 9 mm in length were formed by using the novel Hamburger-electrode.

Study on Glow Discharge Plasma Used in Polyester Surface Modification

To achieve an atmospheric pressure glow discharge (APGD) in air and modify the surface of polyester thread using plasma, the electric field distribution and discharge characteristics under different conditions were studied. We found that the region with a strong electric field, which was formed in a tiny gap between two electrodes constituting a line-line contact electrode structure, provided the initial electron for the entire discharge process. Thus, the discharge voltage was reduced. The dielectric barrier of the line-line contact electrodes can inhibit the generation of secondary electrons. Thus, the transient current pulse discharge was reduced significantly, and an APGD in air was achieved. We designed double layer line-line contact electrodes, which can generate the APGD on the surface of a material under treatment directly. A noticeable change in the surface morphology of polyester fiber was visualized with the aid of a scanning electron microscope (SEM). Two electrode structures - the multi-row line-line and double-helix line-line contact electrodes - were designed. A large area of the APGD plasma with flat and curved surfaces can be formed in air using these contact electrodes. This can improve the efficiency of surface treatment and is significant for the application of the APGD plasma in industries.

Precise energy and temperature measurements in dielectric barrier discharges at atmospheric pressure

A specially designed dielectric barrier discharge (DBD) cell and associated equipment has been used to carry out precise measurements of electrical energy, , dissipated per discharge cycle of the applied ac voltage, Va over the frequency range 5 ⩽ ⩽ 50 kHz. Twin pairs of several different dielectric materials (2.54 cm diameter discs, thicknesses = 2.0 or ca. 0.1 mm) with relative permittivities between 2.1 ⩽ ⩽ 9.5 were used as dielectric barriers in DBDs of four different gases: He, Ne, Ar and N2. Much of the work relates to the study of atmospheric pressure glow discharge (APGD) plasma in flowing He gas; five separate thermometers (including fiber-optic probes immune to high voltage and high-frequency electromagnetic fields) have enabled us to perform a detailed calorimetric (heat balance) investigation in He APGD, believed to be the first of its kind. Fair agreement in the overall energy balance, which includes vacuum ultraviolet (VUV) light emission, lends strong support to the validity of both measurements and methodology. The latter includes refined algorithms that permit rapid data acquisition and processing. The present results are compared with literature, allowing several important conclusions/recommendations to emerge.

Modification of Polyester and Polyamide Fabrics by Atmospheric Pressure Glow Discharge Plasma

In this study, the surface of polyester and polyamide fabric were modified by atmospheric pressure glow discharge plasma (APGD) under different operating conditions to improve the hydrophilicity and printability of the fabric. Different plasma treatment gases i.e., air, oxygen (O2), nitrogen (N2), argon (Ar), and water vapor was investigated. The treatments of PET and PA fabrics by aspartic (Asp.) and sulfamic (Sulf.) acid were done after plasma treatment in order to improve their printability for basic and acid dyes. The plasma exposure time has been changed to control the extent of plasma surface modification. The efficiency of the plasma treatment was assessed through wettability, K/S, and fastness properties measurements. Surface characterization was performed through FTIR and SEM detection. It was observed that wettability, and the color strength of printed PET and PA fabrics were significantly improved by all plasma treatments.

A study of the glow discharge characteristics of contact electrodes at atmospheric pressure in air

Electric field distributions and discharge properties of rod-rod contact electrodes were studied under the condition of DBD for the steady generation of atmospheric pressure glow discharge plasma (APGD) in air. We found that under the effect of the initial electrons generated in a nanometer-scale gap, the rod-rod cross-contact electrodes yielded APGD plasma in air. Regarding the rod-rod cross-contact electrodes, increasing the working voltage expanded the strong electric field area of the gas gap so that both discharge area and discharge power increased, and the increase in the number of contact points kept the initial discharge voltage unchanged and caused an increase in the plasma discharge area and discharge power. A mesh-like structure of cross-contact electrodes was designed and used to generate more APGD plasma, suggesting high applicability.

The effect of anti-TGF-β2 antibody functionalized intraocular lens on lens epithelial cell migration and epithelial–mesenchymal transition

Migration and epithelial–mesenchymal transition (EMT) of lens epithelial cells (LECs) are main causes of central posterior capsule opacification after cataract extraction combined with intraocular lens (IOL) implantation. In this study, commercially available hydrophobic acrylic IOLs were first pretreated with atmospheric pressure glow discharge plasma to produce plenty of negatively charged chemical groups onto IOL surface, then polyethylenimine was deposited onto IOL surfaces as a precursor monolayer, and then anti-TGF-β2 (anti-T) antibody and poly-l-lysine were sequentially deposited onto IOL surface for four cycles followed by another upmost monolayer of anti-T antibody via layer-by-layer self-assembly technique. After the fabrication of anti-T antibody multilayers on IOL surface, the surface characteristics of the anti-T antibody functionalized IOL, as well as its effect on LECs adhesion, proliferation, migration and EMT were then tested in this study. Our results revealed that anti-T antibody multilayers could be successfully immobilized onto IOL surfaces by plasma pretreatment and layer-by-layer self-assembly technique, and could keep stable for at least 3 months on IOL surface. The anti-T antibody immobilized in the multilayers on IOL surfaces showed good immunological activity by its specific antigen-antibody interaction with exogenous TGF-β2. Anti-T antibody functionalized IOL surface was as smooth and flat as the untreated IOL surface. No difference in optical or physical properties was found between the anti-T antibody functionalized IOLs and the untreated IOLs. Compared with the untreated IOLs, the anti-T antibody functionalized IOL greatly inhibited LECs from migration and EMT, yet showed only transient inhibition to LECs adhesion and no inhibition to LECs proliferation. With these data, we demonstrate a simple, inexpensive, and feasible method to fabricate surface functionalized IOL for in situ capture and neutralization of TGF-β2 in the capsular bag, which might be a possible solution to preventing posterior capsule opacification after cataract surgery.

Plasma treatment induces internal surface modifications of electrospun poly(L-lactic) acid scaffold to enhance protein coating

Advanced biomaterials should also be bioactive with regard to desirable cellular responses, such as selective protein adsorption and cell attachment, proliferation, and differentiation. To enhance cell-material interactions, surface modifications have commonly been performed. Among the various surface modification approaches, atmospheric pressure glow discharge plasma has been used to change a hydrophobic polymer surface to a hydrophilic surface. Poly(L-lactic acid) (PLLA)-derived scaffolds lack cell recognition signals and the hydrophobic nature of PLLA hinders cell seeding. To make PLLA surfaces more conducive to cell attachment and spreading, surface modifications may be used to create cell-biomaterial interfaces that elicit controlled cell adhesion and maintain differentiated phenotypes. In this study, (He) gaseous atmospheric plasma glow discharge was used to change the characteristics of a 3D-type polymeric scaffold from hydrophobic to hydrophilic on both the outer and inner surfaces of the scaffold and the penetration efficiency with fibronectin was investigated. Field-emission scanning electron microscope images showed that some grooves were formed on the PLLA fibers after plasma treatment. X-ray photoelectron spectroscopy data also showed chemical changes in the PLLA structure. After plasma treatment, -CN (285.76 eV) was increased in C1s and -NH2 (399.70 eV) was increased significantly and –N=CH (400.80 eV) and –NH3+ (402.05 eV) were newly appeared in N1s. These changes allowed fibronectin to penetrate into the PLLA scaffold; this could be observed by confocal microscopy. In conclusion, helium atmospheric pressure plasma treatment was effective in modifying the polymeric scaffold, making it hydrophilic, and this treatment can also be used in tissue engineering research as needed to make polymers hydrophilic.

Conferring durable antimicrobial properties on nonwoven polypropylene via plasma-assisted graft polymerization of DADMAC

Spunbond nonwoven polypropylene (SB-PP), commonly used for hygienic products, was treated with diallyldimethylammonium chloride (DADMAC) to confer antimicrobial properties. Atmospheric pressure glow discharge plasma was used to induce free radical chain growth polymerization of DADMAC monomer onto the SB-PP in the presence of a crosslinker, which produced a graft polymerized network on the fabric with durable antimicrobial properties. The effects of different DADMAC concentrations and plasma operating condition parameters including the RF power (400–800W) and the time of plasma exposure (0–120s) were studied and the optimum treatment conditions were identified by determining the surface charge density on the treated fabrics. The presence of grafted poly-DADMAC on the polypropylene surface was confirmed using SEM, FT-IR and TOF-SIMS techniques. Antibacterial performance was investigated using the AATCC Test Method 100 for both gram positive and gram negative bacteria, and the antimicrobial test results showed 6 log reductions in the number of bacterial activities of Klebsiella pneumoniae and Staphylococcus aureus on the SB-PP samples, which is unprecedented.

Multi-functional military textile: Plasma-induced graft polymerization of a C6 fluorocarbon for repellent treatment on nylon–cotton blend fabric

This paper reports preparation of a dual functional 50/50 nylon/cotton blend fabric (NyCo) with an anti-bacterial bulk and repellent front surface using atmospheric pressure glow discharge plasma. In this report, a C6 fluorocarbon monomer, 2-(perfluorohexyl)ethyl acrylate was graft polymerized using plasma on the front surface of a nylon–cotton fabric which was already grafted with polyDADMAC for anti-bacterial properties. The surface was characterized by Fourier-transform infrared (FT-IR) spectroscopy and X-ray photoelectron spectroscopy (XPS). The presence of fluorine on the surface was mapped and confirmed by time-of-flight secondary ion mass spectroscopy (TOF-SIMS). Scanning electron microscopy (SEM) images showed a uniform layer of fluorocarbon polymer on the fiber surface. High water contact angle of 144° was obtained on the surface. The surface also achieved a high American Association of Textile Chemists and Colorists (AATCC) Test Method 193 rating of 8 and AATCC Test Method 118 rating of 5 indicating that the surface could repel a fluid with surface tension as low as 25dyn/cm.

Functional Military Textile: Plasma-Induced Graft Polymerization of DADMAC for Antimicrobial Treatment on Nylon-Cotton Blend Fabric

In this study, diallyldimethylammonium chloride (DADMAC), a quaternary ammonium salt monomer, is graft polymerized on 50–50 Nylon-Cotton (NyCo) standard military fabric using atmospheric pressure glow discharge plasma to impart self-detoxification capability. Atmospheric pressure plasma is used to induce free radical chain polymerization of the DADMAC monomer to introduce a graft polymerized network on the fabric with durable antimicrobial properties. Pentaerythritol tetraacrylate (PETA) is used as a cross-linking agent to obtain a highly cross-linked, durable polymer network. The presence of polyDADMAC on the fabric surface is confirmed using acid dye staining, SEM, and TOF–SIMS. Antibacterial performance is investigated using standard AATCC Test Method 100 for both gram positive and gram negative bacteria. Results show 99.9 % reduction in the bacterial activities of Klebsiella pneumoniae and Staphylococcus aureus.

Improving hydrophilicity and protein resistance of silicone hydrogel by plasma induced graft polymerization of 2- methacryloyloxyethyl phosphorylcholine

AbstractSurface properties of silicone hydrogels used as soft contact lenses play an important role in biocompatibility, conformability and deposition of protein. In this report, the surface hydrophilicity and protein deposition resistance of silicone hydrogel were modified using an atmospheric pressure glow discharge plasma (APGDP) induced graft polymerization of 2-methacryloyloxyethyl phosphoryl choline (MPC). Silicone hydrogel was treated with plasma and exposed to air to form oxide and hydroperoxides at the surface, which initiated surface graft polymerization of MPC. Elemental composition and structure at the surface of silicone hydrogel were characterized through ATR-FTIR and XPS. The data of ATR-FTIR and XPS analyses revealed that MPC was grafted onto the surface of silicone hydrogel. Contact angle measurement was used to evaluate the hydrophilic property of the silicone hydrogel. The MPC grafted silicone hydrogel has the contact angle about 55° when MPC solution with the concentration 10 wt% is applied for graft polymerization. The result showed that graft polymerzation of MPC improved the hydrophilicity of silicone hydrogel efficiently. Bovine serum albumin (BSA) was used as a model to investigate protein deposition resistance of the modified silicone hydrogel. The data obtained by bicinchoninic acid assay revealed that the grafted silicone hydrogels had a significant enhancement of protein resistance.

Atmospheric pressure glow discharge plasma polymerization for surface treatment on sized basalt fiber/polylactic acid composites

This study evaluates the effects of atmospheric pressure glow discharge plasma polymerization on basalt fiber to the properties of basalt fiber/polylactic acid composite. Plasma exposure time was the object of interest so the basalt fiber was exposed to the glow for 0.5, 1.5, 3, 4.5, and 6min, respectively. Characterization was conducted on the plasma polymerized fibers by identifying the molecular bonds and surface morphology. Properties (mechanical and thermal) and water absorption behavior of the fabricated composites were tested. Plasma exposure time on BF affected mechanical properties of its BF/PLA composite, showing a decline in mechanical properties until the BF was plasma polymerized beyond 1.5min. Optimum plasma polymerization on BF was for 4.5min of plasma exposure time where the composite’s strength and modulus were 45% and 18% higher, respectively, compared to those of untreated one.

Deepening Effect of Superfine Dyed Polyester by Escaping Electron-Beam Atmospheric Pressure Glow Discharge Plasma

Surface modification of the dyed polyester was performed by the combination of escaping electron-beam atmospheric pressure glow discharge plasma (APGDP) and softener was studied. Apparent depth was tested and the morphological change along the fiber was observed and analyzed by scanning electron microscopy (SEM). Experimental results indicate that surfaces of the treated PET become rougher and have visible traces of etched, and the apparent depth are also significant increased. These results show that: deepening effect of PET is improved clearly and being a good durability.