Diffuse Coplanar Surface Barrier Discharge Research Articles

Modeling the growth of Aspergillus brasiliensis affected by a nonthermal plasma.

The main objective of the study was to develop and validate a model for the growth of Aspergillus brasiliensis on surfaces, specifically on agar culture medium. An additional aim was to determine conditions for complete growth inhibition of this micromycete using two different nonthermal plasma (NTP) sources. The developed model uses two key parameters, namely the growth rate and growth delay, which depend on the cultivation temperature and the amount of inoculum. These parameters well describe the growth of A. brasiliensis and the effect of NTP on it. For complete fungus inactivation, a single 10-minute exposure to a diffuse coplanar surface barrier discharge was sufficient, while a point-to-ring corona discharge required several repeated 10-minute exposures at 24-h intervals. The article presents a model for simulating the surface growth of A. brasiliensis and evaluates the effectiveness of two NTP sources in deactivating fungi on agar media.

Plasma Treatment of Large-Area Polymer Substrates for the Enhanced Adhesion of UV-Digital Printing.

UV-digital printing belongs to the commonly used method for custom large-area substrate decoration. Despite low surface energy and adhesion, transparent polymer materials, such as polymethylmethacrylate (PMMA) and polycarbonate (PC), represent an ideal substrate for such purposes. The diffuse coplanar surface barrier discharge (DCSBD) in a novel compact configuration was used for substrate activation to improve ink adhesion to the polymer surface. This industrially applicable version of DCSBD was prepared, tested, and successfully implemented for the UV-digital printing process. Furthermore, wettability and surface free energy measurement, X-ray photoelectron spectroscopy, atomic force, and scanning electron microscopy evaluated the surface chemistry and morphology changes. The changes in the adhesion of the surface and of ink were analyzed by a peel-force and a crosscut test, respectively. A short plasma treatment (1-5 s) enhanced the substrate's properties of PMMA and PC while providing the pre-treatment suitable for further in-line UV-digital printing. Furthermore, we did not observe damage of or significant change in roughness affecting the substrate's initial transparency.

Effect of atmospheric pressure cold plasma on the physiochemical characteristics and Fourier transform infrared spectroscopy analysis of hazelnuts and peanuts

Abstract Consuming nuts in their raw form becomes a significant concern due to the presence of microbial contamination. The efficacy of low-temperature plasma (LTP) for inactivating fungi on nuts is already known. However, it is also necessary to examine the impact of this technique on physiochemical parameters to demonstrate the safety of LTP, especially when considering its practical application. The aim of the study is the investigation of the effect of LTP on physiochemical parameters, and the possible impact on the ageing of selected nut samples. LTP was generated in ambient air using diffuse coplanar surface barrier discharge (DCSBD). Based on FTIR analysis, no significant changes were detected on the surface of peanuts. In hazelnuts, moderate changes were recorded mainly in regions belonging to lipids. Changes inside the samples were not detected. A slight increase of polyphenol, flavonoid content and antioxidant activity was observed.

Interaction of Cold Atmospheric Pressure Plasma with Soybean Seeds: Effect on Germination and DNA, Seed Surface Characteristics and Plasma Diagnostics

This study investigates the relation between cold atmospheric pressure plasma (CAPP) effect on seeds and the plasma parameters. As a source of CAPP, the diffuse coplanar surface barrier discharge (DCSBD) generated in nitrogen, ambient air, and oxygen at atmospheric pressure was used. Results of germination and the level of DNA damage of soybean seeds (Glycine max L.) treated in plasma and plasma gaseous products showed that the most advantageous is the use of ambient air plasma treatment. The water contact angle (WCA) of samples treated directly in plasma was significantly smaller than that of samples treated with gaseous products. Using attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR), we did not observe significant changes between the spectra of individual samples, what indicates that there is no damage on the surface of the samples during the treatment, only the binding of polar groups. The method of optical emission spectroscopy (OES) and Fourier transform infrared spectroscopy (FTIR) were used to study the plasma parameters. The most radiant system observed in ambient air and nitrogen plasma is the second positive system of nitrogen N2C3∏u→B3∏g\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${\ ext{N}}_{2} \\left( {{\ ext{C}}^{3} \\prod _{{\ ext{u}}} \ o {\ ext{B}}^{3} \\prod _{{\ ext{g}}} } \\right)$$\\end{document}. FTIR measurements showed the presence of reactive oxygen and nitrogen species O3, NO2, N2O, NO, HNO2 depending on the working gas. Finally, it can be assumed that the positive effect of plasma on the seed is caused not only by the individual components of the plasma, but also by their synergistic effect, while the ratio of the individual active particles as well as the plasma exposure to the seeds are important.

Rapid, low-temperature, air plasma sintering of mesoporous titania electron transporting layers in perovskite solar cells

Reducing the sintering temperature and time of mesoporous titanium dioxide (m-TiO2) from the standard thermal approach of baking at 500 °C for 1 h is an important step for employment of mesoscopic perovskite solar cells (PSCs). We present a robust method based on atmospheric pressure ambient air plasma of the diffuse coplanar surface barrier discharge (DCSBD) for sintering of m-TiO2 in 2.5 min at 70 °C. When implemented in PSCs as an electron transport layer an efficiency of (15.8 ± 1.0) % was achieved, which is on the same level as a standard thermal approach. The organic moieties which hinder the perovskite infiltration into the porous structure were removed to a similar extent as the thermal sintering. The approach does not affect the conduction band alignment with the perovskite absorber and an appropriate energy offset is preserved.

Efficacy Comparison of Three Atmospheric Pressure Plasma Sources for Soybean Seed Treatment: Plasma Characteristics, Seed Properties, Germination

Plasma seed treatment has proven to be a useful technique for improving germination, growth dynamics, as well as plant resistance. In this paper, we studied the efficacy of soybean seeds treatment using various sources of cold atmospheric pressure plasma generated in air. We compared three types of plasma treatments: direct treatment with plasma generated by a diffuse coplanar surface barrier discharge (DCSBD), direct treatment with plasma generated by a multi-hollow surface dielectric barrier discharge, and indirect treatment using the gaseous products of plasma generated by an air plasma jet. The composition of plasma generated by each of the sources was analysed using optical emission spectroscopy and Fourier Transform Infrared spectroscopy (FTIR). Parameters of the plasma treatments have been optimized to improve soybean germination. Plasma-treated seeds were examined by the means of water contact angle, surface free energy and imbibition measurements, attenuated total reflectance FTIR (ATR-FTIR), x-ray photoelectron spectroscopy (XPS) and scanning electron microscope (SEM) analyses. Surface analysis by ATR-FTIR and XPS showed changes in the chemical bonds on the surface of the plasma-treated seeds, which led to an increase in wettability and imbibition. SEM analysis confirmed that the plasma treatment is non-invasive and does not cause changes in seed surface morphology. Among the studied sources, DCSBD proved to be the best suited for soybean seed treatment in terms of germination improvement as well as treatment time and energy efficiency.

Fast, scalable, and environmentally friendly method for production of stand-alone ultrathin reduced graphene oxide paper

In the present, there is a big need for materials that can replace materials currently used in technologies, improving mainly the performance and ecological impact of manufacturing. Graphene-based materials are such an alternative, primarily graphene oxide (GO) and reduced graphene oxide (rGO). This work presents a scalable, fast, safe, and eco-friendly method for preparing rGO thin paper (∼5 μm) with conductivity reaching 435 S/m. These rGO papers were fabricated by reducing thin GO paper prepared in an in-house-built vacuum chamber and applying spraying cycles of GO dispersion for a precise and highly controllable deposition process. The atmospheric plasma generated by Diffuse Coplanar Surface Barrier Discharge (DCSBD) plasma source was employed for rapid GO reduction-exfoliation (in the order of seconds) to prepare highly porous rGO paper. Prepared rGO papers were then post-processed by a cold rolling press into uniform conductive self-standing pure rGO papers to create more precisely defined samples and enhance their mechanical and electrical properties. The morphology of GO and rGO papers was studied by SEM and AFM, the chemical changes before/after the plasma reduction were analyzed by the XPS technique and the electrical parameters of the fabricated papers were analyzed by the 4-point probe method and the structure of GO and rGO was analyzed by Raman and XRD methods. The short duration and the scalability potential of the herein-described plasma-reduction-exfoliation method open new possibilities for large-scale implementation of rGO papers in industrial applications.

Application of cold atmospheric plasma for mold inactivation

Mold growth in indoor interiors is an increasing problem that has adverse effects on both occupants and building materials. The aim of this study was to present the new environmentally friendly method (cold atmospheric plasma treatment) for decontamination of indoor environments contaminated by mold spores, with the potential to become an effective replacement for conventional methods, such as ultraviolet-C (UV-C) germicidal irradiation. The spores of Aspergillus species on malt extract agar plates were exposed to plasma produced by diffuse coplanar surface barrier discharge. The surface coverage of mold was evaluated using image analysis. Cold plasma treatment inactivated spores on the surface of the culture medium in 0.5 min, whereas a weak growth delay was observed after 30 minute exposure to UV-C irradiation. This study demonstrated that cold atmospheric plasma is a more effective method for reducing mold spores on agar compared with germicidal UV-C irradiation.

Atmospheric-pressure air plasma sources for cleaning and activation of float soda-lime glass: Effects and comparison

The effects of atmospheric-pressure air plasma treatment on the surface properties of common float soda-lime glass were studied using four different plasma sources. The purpose of the studied treatment was to remove contamination and activate the surface with hydrophilic functional groups, without affecting the surface morphology, by balancing the involved mechanisms. The in-depth chemical XPS analysis, based on the achieved hydrophilic effects and ageing recovery evaluated by WCA measurement, revealed a proportional distribution of the various processes involved, which were complemented by AFM measurements. An exposure time of 1 s caused significant modification of the glass surface with all tested plasma sources, while the specific properties of the obtained effects varied due to individual physical plasma parameters. The effects of the treatment with gliding arc, plasma torch, and multi-hollow surface dielectric barrier discharge exhibited some undesirable properties such as non-uniformity, rapid hydrophobic recovery, thermal damage or unbalanced removal of surface material. Only the treatment with diffuse coplanar surface barrier discharge plasma achieved optimal results that met all the investigated parameters and requirements of conditioning the float glass as an interface for bonding of additional materials. Comparing four plasma sources with different physical characteristics provided valuable information about their potential use for applications that involve adding materials to glass surfaces in the form of thin films, coatings, and layers.

Modification process of selected thermoplastics with cold plasma and evaluation of changes in their properties

AbstractTargeted surface modification of materials is becoming a commonly used process in the production and research environment. This process alters the functional properties of the polymer surface and, under laboratory and manufacturing conditions, can ideally be initiated by a diffuse coplanar surface barrier discharge plasma, also called a cold plasma. The efficiency of the surface modification process by this type of discharge is given mainly by the speed of the plasma‐chemical modification process. An interesting area of research in this area is the characterization of changes in the above plasma chemical modification. The nature of the changes can be observed ideally on the flat surfaces of selected materials, since the height of the visually homogeneous plasma layer is approximately 0.3 mm. During the process of plasma chemical modification, the investigated surface of the polymeric material is also exposed to temperature, electric micro‐discharges, heat flow and ultraviolet radiation. All these elements affect changes that need to be investigated and described. The effect of temperature and micro‐discharges during the cold plasma treatment can be evaluated from thermograms. Visually homogenous plasma respectively heat flow from its generation is first time monitored with Schlieren Imaging system. The effect of degradation (due to ultraviolet radiation) of polymers is monitored with static tensile test.

Characterization of TiO2 nanofibers with enhanced photocatalytic properties prepared by plasma assisted calcination

In this article, we present a novel approach to produce titania (TiO 2 ) nanofibers with enhanced properties using plasma pre-treatment. Nanofibers were produced from electro-spun polyvinylpyrrolidone (PVP) based nanofibers with titanium(IV) isopropoxide (TTIP) as a precursor. PVP/TTIP fibers were plasma treated using diffuse coplanar surface barrier discharge (DCSBD) followed by thermal calcination at 500 °C, 600 °C and 700 °C. The morphology of nanostructures was characterized using SEM, BET and XRD, the chemical composition was analyzed by XPS, ATR-FTIR, the photocatalytic activity was evaluated by degradation of methylene blue and band gap was determined from diffuse reflectance spectra (DRS) using Tauc plot. Initial plasma treatment caused decomposition of polymer matrix, which led to faster oxidation and crystalline phase transition at lower temperature during the following thermal processing/calcination. The results showed enhanced photocatalytic properties of plasma pre-treated fibers despite the fact they possess higher proportion of rutile and lower specific surface area. UV–vis DRS measurements exhibit lower band gap energy at 700 °C, but difference between plasma treated (PT) and non-treated (NT) samples at the same temperature was not observed.

Polyimide Layers with High Refractivity and Surface Wettability Adapted for Lowering Optical Losses in Solar Cells.

The performance of photovoltaics with superstrate configuration is limited by the rigidity and low refractivity of a classical glass cover. In this work, two polyimides (PIs) and two copolyimides combined in the main chain cycloaliphatic moieties, aromatic sequences, chalcogen atoms, and having/lacking fluorine atoms, are proposed as shielding covers for solar cells. The samples containing small cycloaliphatic moieties displayed high transmittance above 80% at 550 nm. The refractive index values under changeable wavelengths and temperatures were shown to influence the magnitude of the reflection losses. At the sample interface with the transparent electrode, optical losses were reduced (~0.26%) in comparison to the classical glass (~0.97%). The samples with the best optical features were further subjected to a surface treatment to render the self-cleaning ability. For this, a new approach was used residing in irradiation with the diffuse coplanar surface barrier discharge (DCSBD), followed by spraying with a commercial substance. Scanning electron microscopy and atomic force microscopy scans show that the surface characteristics were changed after surface treatment, as indicated by the variations in root mean square roughness, surface area ratio, and surface bearing index values. The proposed PI covers diminish the optical losses caused by total internal reflection and soiling, owing to their adapted refractivity and superhydrophobic surfaces (contact angles > 150°), and open up new perspectives for modern photovoltaic technologies.

Large‐area open air plasma sources for roll‐to‐roll manufacture

SummaryThe aim of the current paper is to introduce technology for the generation of high‐power density surface plasma by a diffuse coplanar surface barrier discharge (DCSBD) plasma unit. The diffuse and uniform plasma generated in low‐cost gases such as open air enables easy integration into novel or existing roll‐to‐roll (R2R) lines. We briefly discuss the history of the development of dielectric barrier discharges (DBDs) toward the most advanced plasma sources based on the coplanar arrangement of electrodes. Moreover, we present and discuss the advantages and disadvantages of the effect of volume and coplanar DBD treatments performed in R2R mode on the surface of polyamide. The paper also discusses the potential of R2R plasma treatments for next‐generation applications of novel flexible and printed electronics.

DMA Analysis of Plasma Modified PVC Films and the Nature of Initiated Surface Changes.

The application of DCSBD (Diffuse Coplanar Surface Barrier Discharge) plasma is referred to as the surface modification/activation of materials. The exposure of material surfaces to DCSBD plasma is initiated by changes in their chemical composition, surface wettability and roughness. The given study presents the mentioned plasma application in the context of the modification of the material viscoelastic properties, namely the PVC polymer film. The measurement of viscoelastic properties changes of PVC was primarily examined by a sensitive thermal method of dynamic-mechanical analysis. This analysis allows identifying changes in the glass transition temperature of PVC, before and after DCSBD plasma application, Tangens Delta, supported by glass transition temperatures of Elastic and Loss modulus. The results of the present study prove that DCSBD plasma applied on both sides to PVC surfaces causes changes in its viscoelastic properties. In addition, these changes are presented depending on the variability of the material position, with respect to the winding of the electrodes in the ceramic dielectric generating the DCSBD plasma during modification. The variability of the PVC position holds an important role, as it determines the proportion of filamentous and diffuse components of the plasma that will interact with the material surface during modification. The application of DCSBD plasma must, therefore, be considered a complex modification of the material, and as a result, non-surface changes must also be considered.

Application of diffuse coplanar surface barrier plasma discharge to polymeric materials

AbstractThe KPR 200 mm plasma reactor is a device designed for the surface modification of various materials. Such a modification occurs by applying a unique type of plasma – plasma generated on a ceramic dielectric. The ceramic dielectric is a durable system with which it is possible to continuously modify the surfaces of materials with such a plasma. The advantage of applying this unique type of plasma is that the modification of the materials occurs at room temperature and atmosphere. However, it is necessary to monitor and observe certain parameters, for example: the selected power, the exposure time of the surfaces of the modified materials, and the distance of the surface from the ceramic dielectric itself. Therefore, in the present paper, the effect of diffuse coplanar surface barrier discharge (DCSBD) plasma discharge on selected polymeric materials was investigated. Plasma impact assessment was also performed using image analysis, that could provide relevant information in the process of plasma‐chemical modification. Changes in the surfaces of the investigated thin polyvynil chloride material, before and after exposure to plasma discharge, were also observed (changes in contact angle, atomic force microscopy).

The Influence of Selected Physico-Chemical Factors on Physico-Mechanical Properties of Studied Vulcanizates

The focus of the presented study was set on the influence of physico-chemical factors on the physico-mechanical properties of the investigated vulcanizates containing carbon black filler substitution by mixing alternative fillers. Relating to the alternative partial substituents of fillers, the fine fractions of bentonite, polylactide, polypropylene and coffee grounds have been chosen. The prepared vulcanizates were exposed to various environment conditions which were based namely on DCSBD, plasma discharge (Diffuse Coplanar Surface Barrier Discharge), organic solvent and fungus extract of Piptoporus betulinus. The main objective of the study was to investigate the influence of the selected environment conditions on the physico -mechanical as well as dynamical and mechanical properties of the studied vulcanizates. The effect of chosen alternative fillers and physico-chemical factors on the physico-mechanical properties (elongation, tensile strength and hardness) was evaluated for the studied vulcanizates. Taking into account the chosen environment conditions, the viscoelastic behaviour of the prepared vulcanizates with alternative fillers and reference vulcanizate were evaluated on the basis of the results of the dynamical and mechanical analysis which was resulting from measurements. The measured results show that selected physico-chemical factors in combination with selected alternative fillers affect the physico-mechanical as well as dynamical and mechanical properties of the studied vulcanizates.

ZnO nanofibers prepared by plasma assisted calcination: Characterization and photocatalytic properties

The ZnO nanofibers (ZnO-NF) have been fabricated by the novel approach of plasma assisted calcination using the low-temperature atmospheric pressure plasma generated by diffuse coplanar surface barrier discharge (DCSBD). The electrospun polyvinyl pyrrolidone/zinc acetate fibers were exposed to DCSBD plasma before the thermal processing at different temperatures (400 °C,500 °C and 600 °C) and characterized in term of chemical composition and morphological structure by ATR-FTIR, XPS, SEM, XRD, and BET analysis. The photocatalytic activity of prepared ZnO-NF has been investigated under UV-radiation using methylene blue and the kinetics of photodegradation and reusability were studied. The results showed that initial removal of organic matrix at low-temperature by application of plasma leads to better formation of Zn-O even at lower calcination temperature. The plasma pre-treated (PT) fibers exhibit lower diameter of final products and helps to preserve a well-defined fibrous structure during thermal processing. The ZnO-NF prepared by a combination of plasma treatment and thermal processing showed significantly higher photodegradation activity and the difference was higher with decreasing calcination temperature. The highest rate constants were reached for fibers calcined at 600 °C with and without plasma treatment – kPT = 0.0149 min−1, kNT = 0.0107 min−1, respectively. The slight improvement of re-usability in cyclic photodegradation was observed on samples calcined at 600 °C.

Changes in Surface Characteristics of BOPP Foil after Treatment by Ambient Air Plasma Generated by Coplanar and Volume Dielectric Barrier Discharge.

Biaxially oriented polypropylene (BOPP) is a highly transparent polymer defined by excellent mechanical and barrier properties applicable in the food packaging industry. However, its low surface free energy restricts its use in many industrial processes and needs to be improved. The presented study modifies a BOPP surface using two different atmospheric-pressure plasma sources operating in ambient air and capable of inline processing. The volume dielectric barrier discharge (VDBD) and diffuse coplanar surface barrier discharge (DCSBD) were applied to improve the wettability and adhesion of the 1–10 s treated surface. The changes in morphology and surface chemistry were analyzed by SEM, AFM, WCA/SFE, and XPS, and adhesion was evaluated by a peel force test. Comparing both plasma sources revealed their similar effect on surface wettability and incorporation of polar functional groups. Additionally, higher surface roughness in the case of VDBD treatment contributed to slightly more efficient adhesion in comparison to DCSBD. Although we achieved comparable results for both plasma sources in the term of enhanced surface wettability, degree of oxidation, and stability of induced changes, DCSBD had less effect on the surface deterioration than VDBD, where surface structuring caused an undesirable haze.

New shielding covers based on transparent polyimide/ferrous sulfide composites that reduce optical losses in solar cells

The protective cover glass is an essential element of solar cells in superstrate configuration, determining their efficiency by means of its lightweight, flexibility, optical, morphological and interfacial properties. In this work, a set of new composites based on a fluorinated polyimide and various contents of ferrous sulfide was prepared and characterized for use as shielding covers. FTIR spectra confirmed the structure of the synthesized samples. The transmittance of the obtained films was above 77% at 500 nm at 10% ferrous sulfide, maintaining a good optical clarity upon reinforcement. The measured refraction index ranges between 1.628 (0% filler) and 1.730 (20% filler), rendering a good match with those of the adjacent ITO transparent conductive oxide, which favors reduction of the optical losses. Here is pointed out for the first time, the temperature effect in refractive index and its impact on diminishment of optical losses at interface. The fluorinated structure of the polyimide enables high hydrophobicity that removes the dew related issues, rendering anti-soiling features to the composite samples. Moreover, diffuse coplanar surface barrier discharge plasma exposure of one side of the prepared films enhances the adhesion with the neighboring conductive layer, hence induces a greater compatibility among the solar cell layers.

Effect of cold atmospheric pressure plasma processing on quality and shelf life of red currants

Red currants, berries usually consumed fresh, are prone to fast quality deterioration, due to microbial spoilage. This study evaluates diffuse coplanar surface barrier discharge cold atmospheric pressure plasma (DCSBD CAPP) treatment as a potential decontamination technique for red currants and investigates its effects on microbial load and quality. Red currants were treated with air- and nitrogen-generated CAPP for 0, 5, and 10 min and stored for 10 d at 7 °C. The microbial load and physicochemical quality parameters were measured before and after treatment and during storage. Air-generated CAPP reduced yeasts and moulds load up to 1.28 log CFU g−1, whereas nitrogen-generated CAPP had a significant effect on aerobic mesophilic total viable count (initial reduction of 1.11 log CFU g−1) and not on yeasts and moulds load. Both treatments did not have significant impact on most quality parameters. Results indicated that CAPP could be an effective decontamination technique for red currants, which also ensures the preservation of their antioxidant properties and high nutritional value during storage.