Experimental and Simulation Study of the Spatial-Temporal Distributions of Reactive Oxygen Species Generated by the Compact Medical Plasma Jet: NIGHTINGALE® Using H ₂ And O ₂ Feeding Gases for Medical Applications

Plasma jet applications such as sterilization, surface modification, and material synthesis require precise control of reactive oxygen species (ROS). This study investigates the distribution characteristics of ROS produced by plasma jet (feed gases: H2 or O2) to elucidate their production and transport dynamics. A combined computational–experimental approach was used: a 0D-fluid Global Simulation quantified ROS densities, while COMSOL Multiphysics modeled their spatial distribution. Comparative analysis revealed distinct differences in ROS generation and propagation between the two gases. Quantemol Global Model (QGM) results showed that O2-fed plasma generates significantly higher concentrations of atomic oxygen (O) and O3, whereas H2-fed plasma produces only trace oxygen-containing species, primarily due to O2 diffusion from the surrounding atmosphere. Both simulation and experimental measurements demonstrated effective diffusion of ROS from O2-fed plasma through agar, whereas H2-fed plasma exhibited a non-diffusive, localized distribution. This localized behavior suggests sustained reactivity driven by alternative ROS formation pathways within the medium. By tuning the feed gas composition, plasma jet performance can be optimized for targeted applications: O2-fed plasma is suited for processes requiring strong oxidizing agents, while H2-fed plasma enables applications benefiting from persistent, localized reactivity. These findings offer valuable insights for advancing plasma-based biomedical technologies.