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Iseni S.,Center for Innovation Competence Plasmatis | Reuter S.,Center for Innovation Competence Plasmatis | Schmidt-Bleker A.,Center for Innovation Competence Plasmatis | Weltmann K.-D.,Leibniz Institute for Plasma Science and Technology
IEEE Transactions on Plasma Science | Year: 2014

In this paper, a megahertz atmospheric pressure plasma jet is investigated regarding its discharge pattern in correlation with the flow. Single-shot imaging shows plasma streamer development in a flow pattern determined by turbulent interaction with the atmosphere. Planar laser-induced fluorescence imaging on hydroxyl shows the flow pattern. The discharge pattern is streamerlike. Here, it can be observed that the streamer exhibits a hook-like structure at the end, which might also be attributed to the gas flow pattern. © 2014 IEEE. Source


Fricke K.,Leibniz Institute for Plasma Science and Technology | Koban I.,University of Greifswald | Tresp H.,Leibniz Institute for Plasma Science and Technology | Tresp H.,Center for Innovation Competence Plasmatis | And 6 more authors.
PLoS ONE | Year: 2012

Introduction: The medical use of non-thermal physical plasmas is intensively investigated for sterilization and surface modification of biomedical materials. A further promising application is the removal or etching of organic substances, e.g., biofilms, from surfaces, because remnants of biofilms after conventional cleaning procedures are capable to entertain inflammatory processes in the adjacent tissues. In general, contamination of surfaces by micro-organisms is a major source of problems in health care. Especially biofilms are the most common type of microbial growth in the human body and therefore, the complete removal of pathogens is mandatory for the prevention of inflammatory infiltrate. Physical plasmas offer a huge potential to inactivate micro-organisms and to remove organic materials through plasma-generated highly reactive agents. Method: In this study a Candida albicans biofilm, formed on polystyrene (PS) wafers, as a prototypic biofilm was used to verify the etching capability of the atmospheric pressure plasma jet operating with two different process gases (argon and argon/oxygen mixture). The capability of plasma-assisted biofilm removal was assessed by microscopic imaging. Results: The Candida albicans biofilm, with a thickness of 10 to 20 μm, was removed within 300 s plasma treatment when oxygen was added to the argon gas discharge, whereas argon plasma alone was practically not sufficient in biofilm removal. The impact of plasma etching on biofilms is localized due to the limited presence of reactive plasma species validated by optical emission spectroscopy. © 2012 Fricke et al. Source


Winter J.,Center for Innovation Competence Plasmatis | Winter J.,Leibniz Institute for Plasma Science and Technology | Brandenburg R.,Leibniz Institute for Plasma Science and Technology | Weltmann K.-D.,Leibniz Institute for Plasma Science and Technology
Plasma Sources Science and Technology | Year: 2015

Atmospheric pressure plasma jets have a long history of more than 50 years. During this time their design and plasma generation mechanism has been developed and adapted to various fields of applications. This review aims at giving an overview of jet devices by starting with a brief history of their development. This is followed by an overview of commonly used terms and definitions as well as a survey of different classification schemes (e.g. geometry, excition frequency or specific energy input) described in literature. A selective update of new designs and novel research achievments on atmospheric pressure plasma jets published in 2012 or later shows the impressive variety and rapid development of the field. Finally, a brief outlook on the future trends and directions is given. © 2015 IOP Publishing Ltd. Source


Schnabel U.,Leibniz Institute for Plasma Science and Technology | Schnabel U.,Center for Innovation Competence Plasmatis | Niquet R.,Leibniz Institute for Plasma Science and Technology | Krohmann U.,Leibniz Institute for Plasma Science and Technology | And 4 more authors.
Plasma Processes and Polymers | Year: 2012

Gentle sanitation of fresh fruits and vegetables is highly demanded. Currently used methods lead to losses in product amounts and quality. Furthermore, these methods go along with high costs and chemical residues. One reason for such problems is microbial contamination. Due to the fact that conventional decontamination processes are not suitable for preservation of fresh produce, alternatives such as plasma technology can be helpful. Three different artificial specimen and seeds of Brassica napus were contaminated with endospores of Bacillus atrophaeus and afterwards plasma treated directly with DBD plasma and indirectly with microwave plasma processed air. After a treatment time of 15 minutes reduction rates between 0.5 and 5.2 log were achieved. The viability of seeds was not affected. The advantages of plasma and promising results offer a wide range of possible uses in food industry. The antimicrobial efficacy of a dielectric barrier discharge (DBD) and a microwave plasma setup against Bacillus atrophaeus spores on biological and non-biological surfaces is investigated. Moreover, the establishment of a non-biological specimen for the comparability of different plasma techniques is shown. The decontamination efficiency raised up to 5.2 log cfu/specimen by plasma treatment. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim. Source


Reuter S.,Center for Innovation Competence Plasmatis | Schmidt-Bleker A.,Center for Innovation Competence Plasmatis | Iseni S.,Center for Innovation Competence Plasmatis | Winter J.,Center for Innovation Competence Plasmatis | Weltmann K.-D.,Leibniz Institute for Plasma Science and Technology
IEEE Transactions on Plasma Science | Year: 2014

Formerly so-called bullet jets have been in the focus of atmospheric pressure plasma jet research of the past years. In this paper, two perspectives of the dynamic phenomenon are presented. Averaged, the dynamics appears as a bright spot-the so-called bullet-traveling from the plasma jet nozzle. In single shot it is revealed that the discharge mode in fact is a streamer-type discharge leaving the jet nozzle into the ambient. © 2014 IEEE. Source

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