Separation of VUV/UV photons and reactive particles in the effluent of a He/O2 atmospheric pressure plasma jet

TL;DR

This study introduces an innovative method to separate UV/VUV photons from reactive particles in a plasma jet effluent, enabling more precise analysis of their individual effects on biological samples.

Contribution

The paper presents the X-Jet, a novel plasma jet modification that effectively separates photons from reactive species, facilitating detailed investigation of plasma interactions with biological materials.

Findings

Effective separation of photons and reactive particles achieved

Separate use of photons and reactive species demonstrated on biological samples

The X-Jet simplifies the study of plasma interaction mechanisms

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 ($\mu$-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.