Antimicrobial Treatment of Heat Sensitive Materials by Means of Atmospheric Pressure Rf‐Driven Plasma Jet

Abstract

Since several years a number of activities on the field of antimicrobial treatment by using non-thermal plasmas are known. But although there are quite a few plasma based processes commercially available, the complexity of interaction between plasma and micro organisms prevents the breakthrough of this technology up to now. Thus plasma generation and treatment method needs to be adapted for each individual application. The aim of this work is to demonstrate the industrial applicability of plasma technological processes for medical devices. Therefore a non-thermal plasma jet operated in argon at atmospheric pressure and driven by radio frequency (27.12 MHz) is applied to antimicrobial treatment of samples made of heat sensitive materials, such as used in medical devices. Due to its compact design and low power consumption, typical 10 W to 60 W, it is predestined for modularisation. Therefore it can be adapted to nearly any geometry such as given by medical devices to be treated. The plasma is characterised by UV/VIS optical emission spectroscopy. In order to analyse the effect of the plasma on the micro organisms (Bacillus atrophaeus spores and Escherichia coli vegetative bacteria) microbiological tests are performed. First results on lethal effects of the plasma treamtent will be discussed.

Low temperature atmospheric pressure plasma sources for microbial decontamination

“…In recent years many investigations have been made in order to identify the role of single plasma agents for the microorganism inactivation process (Moisan et al, 2001;Laroussi and Leipold, 2004;Boudam et al, 2006;Brandenburg et al, 2007;Gaunt et al, 2006). Here, UV radiation and highly reactive species such as O, OH and NO x are identified as process relevant components, whereas heat plays a minor role.…”

Diagnostics of an O2–He RF Atmospheric Plasma Discharge by Spectral Emission

“…4 2. Experimental 5 Included in this work is the use of OES for recording the 1 absolute spectral emissions of the atomic and molecular lines a associated with helium, oxygen, nitrogen and hydrogen.…”

“…1 • 6 ) Density of helium 37 metasables atoms can be measured by laser absorption 3s spectroscopy 7 ) and the results of these experiments are 39 dependant on helium gas flow rate. 4 The lifetime of electrons in resonate energy levels are much 5 shorter than the lifetime in an "ordinary" excited energy level 5 ) and is many orders of magnitude shorter than an electrons life time at metastable energy levels. Because of 8 this the quenching of resonate energy levels is negligible and 9 therefore an electron transition that ends on a resonate energy 10 level may be use for the monitoring of an atom's density in 11 its ground state.…”

“…This is especially true because the 48 plasma chemical conversion ofN 2 and 0 2 into NOx is a very 49 efficient process. 4 ) …”

“…The large applicator head allows a laminar flow of 3 gas which is well structured, with a hot and bright core. 4 Moreover, the small amount of 0 2 added to the plasma · / s forming gas (helium) causes the plasma length to be reduced s to couple of millimeters.…”