Low-temperature sterilization with Gas Plasma
Gas Plasma sterilization is one of the latest cold sterilization methods for health care providers. Gas Plasma, widely spread throughout the universe, has been defined as the fourth state of matter: solid, liquid, gaseous and precisely gas plasma. It is composed of free ions and charged particles and is the result of the action of a strong energy field on the gas matter that in the presence of a number of factors is disrupted at the molecular level producing a quantity of unstable particles: ions, atoms, highly reactive neutral free radicals. Simply, it is a gas with great internal energy with a neutral power band that emits free radicals when external electrons are hit by electromagnetic discharges, radio frequencies or microwaves.
The use of hydrogen peroxide in the form of plasma and steam ensures the rapid and effective sterilization of many medical-surgical equipment and materials, leaving no toxic residue. All phases of the sterilization cycle, including that of plasma, take place in a dry environment at low temperature.
Effects of Plasma
- Chemical effects: free plasma radicals can easily have a chemical reaction with polluted materials, leading them to infertility.
- Biological effects: Plasma sterilizes via electrons that destroy the cell wall of bacteria, viruses and other microorganisms.
- Physical effects: the huge amounts of positive and negative ions collide with the foreign particles contained in the air, turning them into charged particles that are forced to polymerize and sediment under the influence of the strong electromagnetic field; finally, these are withheld by special filters.
- The sterilization cycle consists of the following phases:
- Empty: when the material is correctly placed inside the waterked chamber, the system first creates a vacuum state. In this first phase the pressure of the treatment chamber is reduced to 300 militor. The operation to create the vacuum state is performed in a time ranging from 5 to 20 minutes depending on the humidity present.
- Injection: at this point a watery solution of hydrogen peroxide is injected and vaporized inside the treatment chamber. Hydrogen peroxide with suitable concentration has a strong oxidizing effect; when it enters the vacuum sterilization chamber it is gaseous and spreads rapidly.
- Diffusion: the diffusion phase of the gas inside the treatment chamber allows peroxide to spread evenly around the material to be sterilized.
- Plasma: the gas, hit by electromagnetic waves, in the presence of water, decomposes into many active free radicals and spreads on surfaces and in the inner parts. Active gas molecules (essentially free electrons and ions) kill bacteria and microorganisms present.
- Ventilation: after the sterilization process is complete, the pressure inside the chamber returns to the atmospheric pressure, the particles turn into water and oxygen, even with the help of UV rays, without any residue for the surrounding environment.
The phases are controlled by a microprocessor that monitors and ensures the perfect response of sterilization parameters by blocking the cycle in case of anomalies.
Features of the sterilization chamber
Low-temperature hydrogen peroxide is very sensitive to the temperature difference in the sterilization chamber; for this reason, the sterilization chamber was made of aluminum with a good thermal conductivity that allows to maintain the constant temperature. This ensures less sterilization time, homogeneity of chemical treatment and no residue. The thickness of the wall of the room is 8 mm. and anti-oxidant, its lifespan is more than 10 years.
With plasma, it is possible to sterilize:
stainless steel / aluminum / bronze / titanium and other metals / non-metallic such as glass / plastic / poly-acetyl / ethenyl / styrene polymers / ethylene resins / poly methyl methacrylate / non-woven fabric / polyurethane / PVC / nylon / polymers and polycarbonate.
In practice, it is possible to sterilize:
- ultrasound probes
- optical instruments
- electronic instruments
- probes of various kinds
- non-woven fabric
It is not allowed to put in the sterilization chamber:
- hygroscopic materials / articles
- flour products
- water also in bottles
- not completely dried articles.
It is important to know that VitroSteril sterilisers, are able to sterilize hollow bodies PTFE from 0.8 mm in diameter up and up to 2000 mm in length and beyond, while for the stainless steel instrument with open ends, cavities from 1 mm in diameter up to 500 mm in length.
VitroSteril offers the widest range of gas plasma sterilisers now on the market, starting with the 30-litre model, with microwave and radio frequency technology. Plasma allows sterilization at low temperatures; this allows sterilization, free of toxic residues and completely safe for both humans and the environment, even for devices sensitive to humidity and high temperatures.
VitroSteril adopts in all machines a computer control system of all sterilization phases, equipped with touch-screen LCD screen that provides a human-machine conversation platform. Floor models have an easy-to-operate organic incubator to automatically grow and recognize the biological result, and all models are able to store and print sterilization parameter reports.
Sterilisation technologies are essential for the treatment of tools in healthcare facilities
Cleaning or removing contaminants from objects and surfaces precedes sterilization to ensure a level of SAL 10-6 sterile guarantee. Since organic material and salts are known to affect the sterilization capacity of low-temperature technologies, William A. Rutala PhD, et all. from the University of North Carolina studied, and published in 2020, the impact of inadequate cleaning and saline crystalline residues on the effectiveness of sterilization technologies used in the United States.
Steam sterilization has killed all tested organisms; there was no significant difference by comparing the error rate of Ethylene Oxide or Hydrogen Peroxide Gas Plasma. On the other hand, the failure rate of vaporized Hydrogen Peroxide was significantly higher than for other technologies evaluated for both vegetative bacteria and spores (71,7% and 85,6% failure, respectively). In addition, when the negative impact of salts and serum on VHP technology was assessed, it was found that salts, not serum, had the most significant effect on the failure of sterilization.