The generation of reactive species downstream of an atmospheric pressure plasma jet

Atmospheric pressure plasma jets have gained interest in the past decades, due to their efficiency in producing reactive oxygen and nitrogen species (RONS) at low gas temperatures. This makes them especially interesting for biomedical applications because some of the produced species play crucial roles for sudden and programmed cell death. Many plasma sources have been developed for this purpose. However, one of the challenges in the field is to compare the results from different laboratories and plasma sources. To bring the field of plasmas with biomedical applications forward, it would be beneficial to have a standard similar to the gaseous electronic conference (GEC) cell. Such a jet, called the ’COST Reference Microplasma Jet’, was proposed as part of the ‘Biomedical Applications of Atmospheric Pressure Plasmas’ EU COST Action MP1101. However, the reproducibility of this jet, or any other jet has not yet been demonstrated. This was done in is this work by comparing four of these devices for plasma power, temperature of the effluent, ozone and atomic oxygen densities and bacteria inactivation. Having established the reproducibility, more measurements were undertaken for a helium/water/oxygen plasma to measure absolute densities of atomic oxygen, hydroxyl and hydrogen peroxide with laser induced fluorescence techniques, absorption spectroscopy and Fourier-transform infrared spectroscopy in the gas phase in the effluent. It was found that with oxygen admixture added to the water containing plasma, the hydrogen peroxide, ozone and atomic oxygen production can be tailored. Atomic oxygen densities were measured for different water admixtures and gas curtains on a plasma jet. This is more oriented for clinical application, such as through use with the kINPen. It was also found that the atomic oxygen production changes directly above a wet and a dry surface and, thus, possibly alters the amount of reactive species delivered to the same surface when using the kINPen.