Studying the non-thermal plasma jet characteristics and application on bacterial decontamination

Ali F Al-Rawaf,Husham K Oudah,Fadhil Khaddam Fuliful,Mohammed K Khalaf

doi:10.1007/s40094-018-0279-y

Abstract

Non-thermal atmospheric-pressure plasma jet represents an excellent approach for the decontamination of bacteria. In this paper, we want to improve and characterize a non-thermal plasma jet to employ it in processes of sterilization. The electrical characteristics was studied to describe the discharge of the plasma jet and the development of plasma plume has been characterized as a function of helium flow rate. Optical emission spectroscopy was employed to detect the active species inside the plasma plume. The inactivation efficiency of non-thermal plasma jet was evaluated against Staphylococcus aureus bacteria by measuring the diameter of inhibition zone and the number of surviving cells. The results presented that the plasma plume temperature was lower than 34 ^circC at a flow rate of 4 slm, which will not cause damage to living tissues. The diameter of inhibition zone is directly extended with increased exposure time. We confirmed that the inactivation mechanism was unaffected by UV irradiation. In addition, we concluded that the major reasons for the inactivation process of bacteria is because of the action of the reactive oxygen and nitrogen species which formed from ambient air, while the charged particles played a minor role in the inactivation process.

Highlights

Non-thermal atmospheric pressure plasma has attracted considerable attention in biomedical applications due to its simplicity and efficiency [1]
We concluded that the major reasons for the inactivation process of bacteria is because of the action of the reactive oxygen and nitrogen species which formed from ambient air, while the charged particles played a minor role in the inactivation process
It is worth mentioning that the diameter of inhibition zone was always larger than the plasma plume diameter, which can be attributed to the fact that the inactivation occurred mostly due to the action of reactive oxygen and nitrogen species (RONS)

Summary

Introduction

Non-thermal atmospheric pressure plasma has attracted considerable attention in biomedical applications due to its simplicity and efficiency [1]. UV emissions, heat (more than 120 C), ethanol and strong chemicals [2, 3] are effective sterilizing methods for inactivation of microorganisms. These methods have recently raised general disagreements about their environmental effects. Nishime et al [16] evaluated the sterilizing efficacy of a DBD non-thermal helium plasma jet toward Gram-positive and Gram-negative bacteria, and demonstrated that the sterilizing efficacy depends critically on the active species such as ozone. Maisch et al [17] evaluated the antimicrobial effects and the mechanism of cold atmospheric

Objectives

Results

Conclusion