Tempo-spatially Resolved Ozone Characteristics During Single-electrode Dielectric Barrier Discharge (SE-DBD) Operation against Metal and Porcine Skin Surfaces

Abstract

Ozone is a major component produced by low-temperature plasmas operating in oxygen-containing gas mixtures. For correlation with biological or clinical results of plasma medical therapies as well as for evaluation of application security, tempo-spatially resolved ozone concentrations need to be considered. When operating a single-electrode dielectric barrier discharge (SE-DBD), the electric field characteristics are dependent on the geometrical setup as well as the electrical properties of the counter electrode. Thus, the counter electrode also affects the plasma input power and hence the total production of chemical species. Therefore, we studied the power input and the tempo-spatial characteristics of ozone concentrations during operation of a SE-DBD operated at voltage pulses in the µs regime against a clean metal electrode and a metal electrode covered with porcine skin samples. At energy densities of up to 1.85 J/cm 2 , the ozone concentrations in the plasma volume amount to as much as 293 ppm whereas at a distance of 5 and 20 cm, respectively, from the discharge, concentrations have decreased beneath recommended safety limits of 0.1 ppm. Furthermore, significantly lower ozone concentrations could be observed when skin samples were used as part of the counter electrode.

Effect of direct cold atmospheric plasma (diCAP) on microcirculation of intact skin in a controlled mechanical environment

“…Considering the relatively small plasma area in Heuer et al compared to the studies of Kisch et al and our experiments, the pulse energy as well as plasma power density can be assumed the highest in Heuer et al Therefore, the relatively high‐energy input into the skin as well as the plasma (typically leading to high RONS concentrations in the plasma volume) obviously leads to a very pronounced impact on dermal microcirculation. Kisch et al operated their diCAP device with an area of 22.5 cm² at 12 mW/cm² (when operated against a metal counter electrode), whereas in our study, the device with an electrode area of 27 cm² was operated at 4 mW/cm² . Concluding the above findings, the applied plasma power density seems to correlate with quantitative differences in microcirculation enhancement and thus might be a key process parameter.…”

“…For details on typical plasma process parameters, the interested reader is referred to literature . In this work, the power density was determined to be 4 mW/cm² by an approved measurement technique when the single high‐voltage electrode is operated against a metal counter electrode …”

A single application of cold atmospheric plasma (CAP) improves blood flow parameters in chronic wounds

“…The size of the electrode is 9 × 5.5 cm with a plasma area of 27.5 cm 2 , and the device can be plugged into the conventional electrical supply network. 40 Immediately after CAP-application, assessment of blood flow parameters was carried out on the wound.…”

How to produce an NOx- instead of Ox-based chemistry with a cold atmospheric plasma jet

“…The CAP sources that are applied in plasma medical research or in clinical practice are based on different concepts such as dielectric barrier discharges (DBDs), plasma jets, or micro hollow cathode discharge (MHCD), each producing a cocktail of various RONS. However, the amount and composition of this RONS cocktail can vary significantly, e.g., from a nitrogen oxides (NO x )‐dominated plasma chemistry to an O x (atomic oxygen, O, singlet oxygen, , ozone, O 3 )‐dominated chemistry . However, very different CAP source concepts were proven to be effective, e.g., for their antibacterial properties .…”

“…The SteriPlas (Adtec Healthcare Ltd., United Kingdom) is also operated with argon as feed gas, however, it is operated at microwave frequency (2.45 GHz) and produces a hot plasma (more than 800 K at the outlet of the device), resulting in a NO x ‐dominated plasma chemistry . The PlasmaDerm (Cinogy GmbH, Germany) is a floating electrode DBD, which is operated with ambient air as process gas close to room temperature and can hence be expected to produce an O 3 ‐dominated plasma chemistry . To date, it is still largely unclear which RONS composition is favorable for a given medical condition.…”