Separation of VUV/UV photons and reactive particles in the effluent of a He/O₂atmospheric pressure plasma jet

Abstract

Cold atmospheric pressure plasmas can be used for treatment of living tissues or for inactivation of bacteria or biological macromolecules. The treatment is usually characterized by a combined effect of UV and VUV radiation, reactive species, and ions. This combination is usually beneficial for the effectiveness of the treatment but it makes the study of fundamental interaction mechanisms very difficult. Here we report on an effective separation of VUV/UV photons and heavy reactive species in the effluent of a micro scale atmospheric pressure plasma jet (µ-APPJ). The separation is realized by an additional flow of helium gas under well-defined flow conditions, which deflects heavy particles in the effluent without affecting the VUV and UV photons. Both components of the effluent, the photons and the reactive species, can be used separately or in combination for sample treatment. The results of treatment of a model plasma polymer film and vegetative Bacillus subtilis and Escherichia coli cells are shown and discussed. A simple model of the He gas flow and reaction kinetics of oxygen atoms in the gas phase and at the surface is used to provide a better understanding of the processes in the plasma effluent. The new jet modification, called X-Jet for its appearance, will simplify the investigation of interaction mechanisms of atmospheric pressure plasmas with biological samples.

Effect of Additive Oxygen on the Reactive Species Profile and Microbicidal Property of a Helium Atmospheric Pressure Plasma Jet

“…Schneider et al observed similar large, disk‐shape inactivation patterns in a μ‐APPJ ignited in a He/O 2 mixture . Measurements using molecular beam mass spectrometry revealed significantly high production of O and O 3 by the μ‐APPJ with O 2 added.…”

“…Measurements using molecular beam mass spectrometry revealed significantly high production of O and O 3 by the μ‐APPJ with O 2 added. Therefore, the inactivation of E. coli at large distances from the jet axis was attributed to O 3 because of its rather long life time …”

“…Therefore, the inactivation of E. coli at large distances from the jet axis was attributed to O 3 because of its rather long life time. [59]…”

Virucide properties of cold atmospheric plasma for future clinical applications

“…Contemporary, a widely accepted assumption concerning the biological CAP-mediated mechanisms is the occurrence of reactive oxygen and nitrogen species (ROS, RNS) [Bekeschus et al, 2014;Weiss et al, 2015b]. ROS and RNS are only two factors among various biologically reactive particles in the highly reactive-ionized gas, further containing ions, electrons, excited atoms and molecules, free radicals, photons, and electromagnetic fields, subsequently emitting visible ultraviolet, vacuum-ultraviolet, and infra-red radiation [Ahn et al, 2011;Heinlin et al, 2011;Schneider et al, 2011]. CAP treatment of biological tissues and cells becomes feasible due to CAP can be operated at 37-38˚C.…”

Atmospheric Pressure Pulsed-Periodical Spark Generator Forming Fast Moving Non-Equilibrium Plasma Clouds

“…[1]- [3] (cold treatment means that the average gas temperature in plasma jet at the target is close to room temperature). NTP itself is a gaseous mixture containing wide spectrum of biochemically active agents, specific types of which depend on plasma-forming gas mixture.…”