Design-Driven Optimization of Electrode Geometry and Material for Enhanced RONS Production in Cold Atmospheric Plasma

Cold atmospheric plasma (CAP) has emerged as a versatile tool in biomedical engineering because of its ability to generate reactive oxygen and nitrogen species (RONS) such as OH, H₂O₂, NO, NO₂, and O₃ at near-room temperatures. These reactive species are known to promote wound healing, tissue regeneration, and microbial inactivation without causing thermal damage. This study investigates the influence of electrode geometric parameters—specifically the material type, electrode length, and inter-electrode spacing—on both the physical behavior of the plasma and the chemical generation of RONS. A two-dimensional axisymmetric model was developed using COMSOL Multiphysics 6.1 to simulate the coupled effects of electric fields, fluid flow, and reactive species transport under conditions relevant to medical plasma systems. Simulations were carried out for four electrode materials (copper, silver, steel, and tungsten) and three dimensions for both length and spacing (1.0, 1.5, and 2.0 cm). The results revealed that an electrode length of 2 cm achieved the most balanced and efficient plasma discharge, providing the strongest production of short-lived reactive species such as OH and H₂O₂. Among the materials, silver demonstrated superior chemical activity followed by steel, while copper showed balanced performance, and tungsten excelled only in physical parameters. The simulated outcomes showed good agreement with previously reported experimental observations, confirming the model’s validity. Overall, the findings emphasize the critical role of electrode geometry and material in optimizing RONS generation for biomedical applications. The developed model offers a reliable predictive framework for designing plasma sources tailored to specific medical objectives such as sterilization and wound treatment.