Today our topic of discussion is Plasma Sterilization.
Plasma Sterilization
Plasma is basically ionized gas. When applied by an electric field, it gets ionized into electrons and ions. These free radicals and ions interact with living organisms and destroys them.Most of the research in plasma sterilization pertains to volume discharge.
Triphasic behavior was observed in these experiments. The process involves UV irradiation, photo-desorption and chemical etching. The spores are basically made up of simple atoms like C, O, N, H and the like.
The radicals react with these atoms to form simple compounds like CO,, which can subsequently be flushed out. When the organism loses such atoms that are intrinsic to its survival, it dies.
Phases of Plasma Sterilization
Vacuum: Medical instruments are placed in the sterilization chamber (4 cubic feet in capacity). The chamber is sealed and air is pumped out to create a strong vacuum.
Injection: A solution of 59% hydrogen peroxide and water (from a cassette inserted by the operator at the beginning of every 10 cycles) is automatically injected into the sterilization chamber.
Diffusion: The solution vaporizes and diffuses throughout the chamber, surrounding the items to be sterilized. Hydrogen peroxide exhibits antimicrobial activity and is capable of inactivating microorganisms that it encounters in the sterilization chamber.
Plasma: Radio frequency (RF) energy is applied to create an electrical field, which in turn initiates the generation of the low-temperature plasma, i.e. a cloud of reactive and unstable species. These unstable particles collide with one another to produce a variety of new species, including free radicals that, like the hydrogen peroxide vapor, are capable of inactivating any microorganisms, viruses, or spores that may be encountered within the sterilization chamber.
In the plasma phase, the activated components ultimately lose their high energy and recombine to form primarily oxygen and water vapor. The combination of the diffusion pretreatment and plasma phases acts to sterilize while eliminating harmful residuals.
Vent: The RF energy is turned off, the vacuum is released. and the chamber is filled with filtered air, returning it to normal atmospheric pressure.After 10 sterilization cycles, the cassette self-ejects into an internal receptacle for futere dosposal.
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