"Plasma" is an ionized gas – the so-called fourth state of matter (the others being solid, liquid and gas) – and is generated by being energized up to 100,000 degrees or more. Natural examples for plasmas are the sun – a gigantic plasma ball – or lightning on Earth - temporary electrical discharges.
Cold atmospheric plasmas (CAP) are partially ionized gases, that means only one particle out of 1 ∙ 109 is ionized. The advantage of cold atmospheric plasmas is that they are "cold", within the meaning that they operate under room temperature and can be produced at atmospheric pressure on Earth.
From the technological point of view the easiest and furthermore most cost-effective way for generating cold plasma is the "Surface Micro Discharge" technology, which was developed and patented at the Max Planck Institute for Extraterrestrial Physics and which is now being commercialized at terraplasma GmbH.
With this "Surface Micro-Discharge" technology millions of controlled micro-discharges can be generated, which locally ionize the surrounding gas (e.g. the ambient air). As a consequence more than 600 chemical reactions take place, which produce a reactive mix – the so-called "plasma cocktail" - composed of electrons, ions, excited atoms and molecules, reactive species and UV radiation.
This "plasma cocktail" inactivates very efficiently bacteria – independent of the specie and resistance against antibiotics – as well as viruses, fungi and spores.
Based on the research with different plasma sources, it is known that plasma components can be generated in different concentrations, and as a result, various plasma sources do have different effectiveness. The diversity of sources is large and correspondingly not every plasma source suits every application.