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Plasma Sterilization disinfection

Sterilization and disinfection with plasma, how does this work?

Plasma is a very reactive ionized gas that consists of free electron, ions excited atoms, free atoms, the so-called Radical molecule fragments und photons (visible light and UV light).

You can read more under “what is plasma”

It is proven that plasma damages all parts of the pathogens (bacteria, viruses, fungi).
Thus, the pathogens envelopes are destroyed amongst other effects, the cell membranes and DNA genetic information of the pathogen are also destroyed.
Plasma also kills or renders the bacteria, viruses, virion (virus particles that exist outside of a cell, the transmission mechanism or the virus), prions and fungi that may be already present inactive.
It also cleans the surfaces of contamination and toxins.
Due the excellent crack penetration of the low-pressure plasma even the smallest of cracks and cavities are reached by the plasma disinfection / sterilization.
Scientific studies have proved that the sterilizing effect of low pressure plasma is based on several effects, amongst others these are:

The high reactivity of the particles in the plasma

  • The different reactive species that exist in the plasma damage the organic molecules of the living organisms such as bacteria.
  • Bacteria are killed by the oxides existing in the plasma

The UV light present in low pressure plasma

  • Viruses are rendered inactive by the UV light in plasma.
  • Bactria are killed by the UV light in plasma.
  • UV light is an effective disinfections method.
    The UV light damages the genetic information in the DNA molecules.
    Because of this not only living cells like Bacteria for example, but also virus that do not have their own metabolism are destroyed.

The high kinetic energy in the ions and electrons

  • The plasma particles hit the surface of the product with high speed and sputtering off the existing contamination and pathogens.
    Independent of the nature of the contaminating particles, living or not, they are mechanically removed.
    They are transferred into the gas phase and due to the constant gas flow transported from the plasma chamber.
  • The charged particles destroy bonds in the cell membranes and hence reach the Virus envelopes from enveloped viruses (Information: The SARS-CoV-2 are such enveloped viruses).

Low pressure plasma - fine vacuum

  • Due to the vacuum in the plasma chamber and the increased temperature due to contact with the reactive high energy plasma particles the organisms of the pathogens will be dehydrated.

Materials and products suitable for low pressure plasma sterilization or disinfection

Which materials can be sterilized or disinfected in plasma?

Materials

The list of compatible materials for low pressure plasma treatment is long.

Metals, polymers (plastics), elastomers, TPU, Silicone, glass, ceramics, textiles and membranes are all compatible with low pressure plasma sterilization.
Basically, any materials that are not damaged by vacuum or plasma.
For example, foamed materials with closed cells are not compatible.
Not suitable are materials that have a high outgassing as this may hinder the generation of the fine vacuum.

Products suitable for low pressure plasma sterilization

Typically, products that are suitable for low pressure plasma sterilization or disinfection are found in the pharmaceutical, medical and packing industries.
For the low pressure sterilization, the products must fit in the chamber.
The plasma cannot reach products that are already packed, in such cases only the external packing will be sterilized and not the product itself.
For example, the following products are ideally suited for low pressure plasma sterilization or disinfection:

  • Face Masks
  • Safety glasses
  • Protective clothing
  • OP instruments
  • Dentists instruments

Also, FFP3 face masks and other protective items for clinic and hospital personnel that are normally single use items can be sterilized and reused.

Recommended plasm systems and processes for disinfection and sterilization

The choice of the suitable system and process is dependent on the product to be treated and the volume to be treated and the required result.
Should the process take place in a production line or be a central plasma sterilization for a group of businesses clinics or hospitals
maybe a service offered by a local authority, then a large volume system is more suitable.
The plasma sterilization system will be manufactured to meet any special requirements of the product to be sterilized, or the existing infra structure or production.
The plasma system can also be designed to form a clean lock to keep sterilized goods separate from incoming contaminated goods.

The rotating drum plasma systems or interlocking double door system could be of special interest for such applications.
See the film of our system in action. For a mobile application or a smaller clinic then oursmaller laboratory or small production plasma system will be better suited.
The choice of the process gas and process will be dependent on the product to be sterilized, we will advise you on this.

Definition of plasma cleaning, plasma disinfection and plasma sterilization.

Dependent on the desired level of cleanliness from the product or surfaces the best process is selected.
Do you want to clean, disinfect or sterilize, different low pressure plasma process give different results.
The important fact in this decision is the desired reduction in the germ count.

Cleaning

Under plasma cleaning it is generally understood that there will be a general removal of contamination and microorganisms
without necessarily deactivating or killing these.
In a medical area cleaning is often done with cloths or vacuum cleaners.
In a plasma chamber the mechanical removal of microorganisms occurs by a sputter effect.
So a cleaning process will achieve about an 50 – 80% reduction in the germ count (See KRINKO guide lines).

Disinfection

A disinfection reduces the count of health damaging germs so that the treated item presents no danger of infection.
The process is focused on reducing and not completely eliminating and deactivating the pathogens and germs.
An effective disinfection is defined as reducing the germ count by 84–99.9%.
Dependent on the process choice, intensity and time in the plasma atmosphere can the product disinfected and sterilized.

Sterilization

Under sterilization it is understood that during the process a complete and irreversible destruction and inactivation of all microorganisms including those in incubation.
This means sterile products are free from spores, fungi, germs or bacteria capable of reproduction.
Also Prions, viruses and virion must be inactivated.
Dependent on the choice of the plasma intensity, process gas and time in the plasma atmosphere the product will be both disinfected and sterilized.