Effect of Dielectric and Liquid on Plasma Sterilization Using Dielectric Barrier Discharge Plasma (original) (raw)
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Sterilization using dielectric barrier discharge at atmospheric pressure
Fourtieth IAS Annual Meeting. Conference Record of the 2005 Industry Applications Conference, 2005., 2005
A newly developed plasma method has advantages of low temperature operation, time-saving and non-toxicity over the conventional methods, such as dry heat, steam autoclave, γ-ray irradiation and ethylene oxide (EtO) gas. Dielectric barrier discharge (DBD) can be exposed to plasma under atmospheric pressure. The effect of sterilization of Bacillus subtilis and Eschelichia coli (E. coli) was investigated using DBD plasma under dry and wet conditions at atmospheric pressure. The results show that the plasma sterilization method is relatively high speed for Bacillus Subtilis spore compared with conventional methods. The wet plasma method showed higher performance compared with the dry method. These results suggest that H 2 O plays an important role in the sterilization using the DBD plasma.
Dielectric barrier discharge (DBD) devices are known ozone generators. Authors have previously demonstrated a DBD surface plasma source, operating in air at atmospheric pressure, to achieve killing of vegetative cells in 2-3 min and sterilization in 20 min (bacterial spores). The aim of this paper is to examine the role of the ozone in surface DBD plasma sterilization. The role of ozone in plasma killing is examined by a) characterizing the rate of production/decay of ozone during DBD plasma generation, b) studying the effect of exposing bacteria (Escherichia coli) solely to the ozone thus produced. Our results indicate that while ozone plays a major role, the energy flux delivered to the electrodes is also crucial in the process of plasma sterilization.
Plasma for air and water sterilization
2008
This chapter describes the research efforts of Drexel Plasma Institute (DPl) in the area of plasma-based air and water sterilization. Motivation of this research is presented as well as the methods for selection of parameters for the experimental systems. Experimentally obtained results for air sterilization demonstrate that the direct influence of plasma charged particles on airborne bacteria in combination with active chemical substances generated by plasma is the probable reason for high sterilization efficiency of the Dielectric Barrier Grating Discharge (DBGD). Energy input on the level of 13 kJ/m3 is enough to reach a 5-log reduction of viable E. coli bacteria. Experimentally reached D-value (the dosage required for a 90Yo reduction of the number of viable microorganisms) for E. coli bacteria deactivation in water using spark discharge is very low, about 125 kJlm3, and UV-radiation is the most plausible sterilization factor in this case. A new seminumerical model is proposed for initial phase of electrical breakdown in water.
Journal of Applied …, 2009
Atmospheric pressure dielectric barrier discharge ͑DBD͒ plasma has been employed on Gram-negative bacteria, Escherichia coli BL21. Treatment was carried out using plasma generated with different compositions of gases: CH 4 / N 2 ͑1:2͒, O 2 , N 2 / O 2 ͑1:1͒, N 2 , and Ar, and by varying plasma power and treatment time. E. coli cells were exposed under the DBD plasma in triplicates, and their surviving numbers were observed in terms of colony forming units. It has been observed that the CH 4 / N 2 plasma exhibits relatively higher sterilization property toward E. coli compared to plasma generated by using O 2 , N 2 / O 2 , N 2 , and Ar gas mixtures. The time to kill up to 90% of the initial population of the E. coli cells was found to be about 2-3 min for CH 4 / N 2 and O 2 gas mixture DBD plasma. A prolongation of treatment time and an increase in the dissipated power significantly improved the E. coli killing efficiency of the atmospheric pressure DBD plasma.
Air and Water Sterilization using Non-Thermal Plasma
2007 IEEE Pulsed Power Plasma Science Conference, 2007
The sterilization effect of plasma on air and water were investigated in this study * . For air sterilization, a small scale model of HVAC was designed and Dielectric Barrier Discharge plasma source was used for treatment of air. This PDRF (Pathogen Detection and Remediation Facility) consisted of a circulatory airflow system, a plasma chamber and a sampling system. Air sterilization experiments were performed and the inactivation of Escherichia coli was studied. Conventional water sterilization methods such as chlorination, ozonation, filtration, UV irradiation etc have several drawbacks. Pulsed plasma discharge for the destruction of microorganisms in waste water and potable water is a cost effective technique developed recently. The energy efficiency of different types of plasma discharges in water contaminated with Escherichia coli has been studied. The effect of initial concentration of bacterial solution on the inactivation efficiency has also been studied 1-4244-0914-4/07/$25.00 ©2007 IEEE.
Science and technology Indonesia, 2023
Research on the inactivation of Escherichia coli causing diarrheal disease using non-thermal plasma SDBD has been carried out. SDBD is a new technique for non-thermal plasma generation with several advantages: low power generation, comprehensive treatment area coverage, and reducing the potential effects of burning and drying tissue. This study aimed to analyze the effect of treatment time variations, namely 0 as control, 60, 75, 90, 105, and 120 seconds and treatment distance variations of 3, 6, 9, 12, and 15 mm of non-thermal plasma treatment of SDBD on E. coli. The results of the non-thermal plasma SDBD treatment with variations in time and distance showed that the longer the treatment time, the more bacterial cells died. Colony counts decreased to 4.33 x 10 7 CFU/mL compared to the control, 409 x 10 7 CFU/mL, with a treatment time variation of 120 seconds, yielding the best treatment results. At the same time, the results of the treatment for variations in the non-thermal plasma distance of SDBD showed that the smaller the treatment distance, the greater the bacterial death rate, with the best treatment results at a 3 mm treatment interval, with colony counts of 8 x 10 7 CFU/mL, compared to 409 x 10 7 CFU/mL in control. Based on these results, SDBD non-thermal plasma treatment can be used to inactivate or kill bacteria with effectiveness in killing bacteria depending on the length of treatment time and the distance of treatment.
Investigation of the Roles of Plasma Species Generated by Surface Dielectric Barrier Discharge
Scientific Reports
As an emerging sterilization technology, cold atmospheric plasma offers a dry, non-thermal, rapid process that is minimally damaging to a majority of substrates. However, the mechanisms by which plasma interacts with living cells are poorly understood and the plasma generation apparatuses are complex and resource-intensive. In this study, the roles of reactive oxygen species (ROS), nitric oxide (NO), and charged particles (ions) produced by surface dielectric barrier discharge (SDBD) plasma on prokaryotic (Listeria monocytogenes (Gram-positive)) and eukaryotic (human umbilical vein endothelial cells (HUVEC)) cellular function were evaluated. HUVEC and bacterial oxidative stress responses, the accumulation of nitrite in aqueous media, air ion density, and bacterial inactivation at various distances from SDBD actuators were measured. SDBD actuator designs were also varied in terms of electrode number and length to evaluate the cellular effects of plasma volume and power distribution. NO and ions were found to contribute minimally to the observed cellular effects, whereas ROS were found to cause rapid bacterial inactivation, induce eukaryotic and prokaryotic oxidative stress, and result in rapid oxidation of bovine muscle tissue. The results of this study underscore the dominance of ROS as the major plasma generated species responsible for cellular effects, with ions and RNS having a secondary, complimentary role. Cold atmospheric plasma has been heavily investigated in recent years due to its many potential benefits in the field of healthcare, mainly for applications in disinfection and sterilization 1-5 , wound healing 6-8 , and cancer treatment 9-11. Various cold plasma technologies have shown effectiveness against drug-resistant bacteria and are currently being reviewed for clinical applications 12-14. Additionally, this technology has been extensively investigated in different forms for multiple food decontamination applications 15,16. However, many of the current designs used to generate cold plasma rely on direct plasma exposure 14 , consist of complex apparatuses, and require an external gas flow for distribution of plasma-generated species to treatment sites 17-21. As a result, there is a strong need for an effective, inexpensive, and versatile cold plasma generation technology with a simple design for broad applications in surface decontamination and sterilization. As previously described 1,22 , surface dielectric barrier discharge (SDBD) is a novel method of non-thermal plasma generation that overcomes these drawbacks: it has low power requirements, greater treatment flexibility, and an increased effective treatment range. Since SDBD plasma generation is a semi-direct method of exposure to plasma species and does not require the substrate to complete the electric circuit, potential negative effects such as burning and tissue desiccation can be mitigated. SDBD exposure has shown a dose-based differential response in eukaryotic cells 23 and lethal effects on prokaryotic cells 1,4,22,24. It was observed that prokaryotic cells have a lower tolerance to plasma-generated species than eukaryotic cells 22,24 and therefore surface decontamination of eukaryotic tissues may be possible without adverse effects on the treated tissue. SDBD, being a surface treatment, may provide an alternative for precision surface treatments in hospitals, medical facilities, and dermatological applications. Although investigated for many years for flow control applications 25-30 , the effects of different SDBD design parameters on the production and concentration of plasma-generated species has not been well defined. Different
Food Engineering Reviews, 2020
Microbial inactivation efficacy of plasma generated by a custom-made floating electrode dielectric barrier discharge (FE-DBD) or cold plasma at three different frequencies (1 kHz, 2 kHz, and 3.5 kHz) was experimentally evaluated for its inactivation of the pathogen surrogate Enterobacter aerogenes on a glass surface to obtain inactivation kinetics. COMSOL Mul-tiphysics® was used to numerically simulate the amount and the distribution of reactive species within an FE-DBD system. Microbial inactivation kinetics was predicted using species concentrations and microbial inactivation rates from the literature and compared with experimental data. The results showed that the FE-DBD plasma treatment achieved a microbial reduction of 4.3 ± 0.5 log CFU/surface at 3.5 kHz, 5.1 ± 0.09 log CFU/surface at 2 kHz, and 5.1 ± 0.05 log CFU/surface at 1 kHz in 2 min, 3 min, and 6 min, respectively. The predicted values were 4.02 log CFU/surface, 4.10 log CFU/surface, and 4.56 log CFU/surface at 1 kHz, 2 kHz, and 3.5 kHz, respectively. A maximum 1 log difference was observed between numerical predictions and the experimental results. The difference might be due to synergistic interactions between plasma species, UV component of FE-DBD plasma, and/or the electrical field effects, which could not be included in the numerical simulation.
Low pressure plasma discharges for the sterilization and decontamination of surfaces
New Journal of Physics, 2009
The mechanisms of sterilization and decontamination of surfaces are compared in direct and post discharge plasma treatments in two low-pressure reactors, microwave and inductively coupled plasma. It is shown that the removal of various biomolecules, such as proteins, pyrogens or peptides, can be obtained at high rates and low temperatures in the inductively coupled plasma (ICP) by using Ar/O 2 mixtures. Similar efficiency is obtained for bacterial spores. Analysis of the discharge conditions illustrates the role of ion bombardment associated with O radicals, leading to a fast etching of organic matter. By contrast, the conditions obtained in the post discharge lead to much lower etching rates but also to a chemical modification of pyrogens, leading to their deactivation. The advantages of the two processes are discussed for the application to the practical case of decontamination of medical devices and reduction of hospital infections, illustrating the advantages and drawbacks of the two approaches.
Application of an atmospheric dielectric barrier discharge for inactivation of bacteria
An atmospheric pressure dielectric barrier discharge (DBD) system capable of operating under both positively biased voltage pulses at 500 Hz and sinusoidal AC voltage at 8.5 kHz was constructed. The 500 Hz operation produced DBD plasma that was visually more uniform, whilst optical emission from DBD at 8.5 kHz operation was more intense. Though the inactivation of Gram-positive bacteria, Bacillus cereus took longer time than the Gram-negative bacteria, Escherichia coli ATCC 25922 and Salmonella enteritidis, complete sterilization was generally achieved in about 1 minute of DBD plasma treatment.