Cold plasma is a partially ionized gas consisting of a variety of charged and neutral particles. It contains so-called reactive species (RONS – Reactive Oxygen and Nitrogen Species), which make up the majority of the payload of cold plasma. These “active substances” include reactive oxygen (ROS) and nitrogen species (RNS), such as ozone (O₃), hydrogen peroxide (H₂O₂), nitrogen monoxide (NO) and hydroxyl radicals (OH). These species have a strong disinfectant effect and play a crucial role in plasma medicine and water and air purification.

Electrons are accelerated by electric fields and collide with neutral gas atoms, causing ionization, dissociation and excitation to occur. Ions formed in plasma can also drive chemical reactions, particularly in modifying the surface of materials or killing microorganisms. Due to the different temperatures of the electrons and heavy particles, there is only a small amount of heat generated in the plasma. In cold plasma, the total energy always remains low enough to avoid thermal damage to living tissue.

Cold plasma also produces some ultraviolet radiation (UV), which can contribute to sterilization. This radiation also works synergistically with the reactive species to destroy microorganisms. High-frequency electric fields keep the cold plasma stable and control ionization. These fields influence charged particles in the plasma and can be used specifically for material processing or cell stimulation.

Cold plasma also often emits visible light, which can appear in different colors depending on the gases used. These luminous phenomena arise from the recombination of electrons with ions or from the transition of excited atoms to a lower energy level.