Atmospheric discharge cold plasma technology has been employed by the medical community for several years. Examples of high power uses include tissue ablation, suture sealing and sterilization of a tissue area. Low power uses may include dermatologic, hemostasis and other health-field related applications.
The term “cold plasma” is used to indicate that only a small fraction of the inert carrier gas is ionized, although this fraction can be adjusted to suit the particular use or application. Typically, the ionized portion of the carrier gas can range between approximately 10−6 (a very weak plasma beam) to approximately 10−3 (a strong beam). A plasma can be formed where a gas is exposed to a specific amount of energy, and that energy exposure separates the gas component molecules into a collection of ions, electrons, charge-neutral gas molecules, and other species in varying degrees of excitation. Effectiveness has been demonstrated in rapid sterilization, decontamination and industrial processing. Unlike semiconductor industry applications, the cold plasma technology does not require a vacuum chamber. The plasma discharge is conducted in the open air.
The mean electron energy (or temperature) of a cold plasma is considerably higher than that of the bulk-gas molecules. Energy is primarily added to the electrons rather than the ions and background gas molecules, and the electrons can attain energies of approximately 10−1 eV or higher, while background gas remains at ambient temperature. A significant energy savings can be realized since electrons are preferentially excited and larger ions are left in a lower energy state in a cold plasma.
A plasma may also be formed when a modulated electric field is applied to a pair of electrodes and exposed to the gas. The plasma formation can cause oxygen molecules of the air passing near the electrodes to break down into component molecules, including reactive oxygen species (“ROS”). Organic substrates, such as bacteria, viruses, microbes and mold spores can be exposed to ROS, and then destroyed or rendered harmless rapidly. The same reaction can convert much or all of the ROS back into oxygen.
Cold plasmas can provide rapid decontamination of clothing, equipment or gear, and sterilization of medical equipment or food. However, while present methods of decontamination and sterilization may require long periods of time, even hours or days and generate damaging heat in the process; a cold plasma of the present disclosure can often sanitize an area or object very briefly, in seconds or minutes.
It would be advantageous in a number a fields to provide a cold plasma that can decontaminate or sterile large areas rapidly.