Characteristics of 2.45 GHz Surface-Wave-Sustained Argon Discharge for Bio-Medical Applications

Evgenia Benova,Radka Tafradjiiska-Hadjiolova,Todor Bogdanov,Plamena Marinova,Todor Hikov,Zafer Sabit,Ivan Tsonev,Lubomir Traikov,Dimitar Bakalov,Nikolay Valchev

doi:10.3390/app12030969

Evgenia Benova, Radka Tafradjiiska-Hadjiolova + Show 8 more

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https://doi.org/10.3390/app12030969

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Abstract

Cold atmospheric plasma (CAP) applications in various fields, such as biology, medicine and agriculture, have significantly grown during recent years. Many new types of plasma sources operating at atmospheric pressure in open air were developed. In order to use such plasmas for the treatment of biological systems, plasma properties should fulfil strong requirements. One of the most important is the prevention from heating damage. That is why in many cases, the post-discharge region is used for treatment, but the short living particles in the active discharge zone and reactions with them are missed in that case. We use the active region of surface-wave-sustained argon plasma for biological systems treatment. The previous investigations showed good bactericidal, virucidal, seeds germination and decontamination effects at a short treatment time, but the discharge conditions for bio-medical applications need specific adjustment. A detailed theoretical and experimental investigation of the plasma characteristics and their possible optimization in order to meet the requirements for bio-medical applications are presented in this paper. The length of the plasma torch, the temperature at the treatment sample position and the microwave radiation there are estimated and optimized by the appropriate choice of discharge tube size, argon flow rate and microwave power.

Highlights

The low-temperature, non-equilibrium atmospheric pressure plasmas have attracted increasing interest as simple and less expensive plasma sources operating in open space for applications in biology, medicine, agriculture, and the food industry [1,2,3,4,5,6,7,8,9,10]
We found some regimes of operation allowing a microwave plasma torch to be applied for the treatment of biological systems without thermal damage
For comparing the results, the end of the plasma torch is at position z = 0, and the surfatron position is on the left side of the graph

Summary

Introduction

The low-temperature, non-equilibrium atmospheric pressure plasmas have attracted increasing interest as simple and less expensive plasma sources operating in open space for applications in biology, medicine, agriculture, and the food industry [1,2,3,4,5,6,7,8,9,10]. Various types of atmospheric pressure plasma sources were developed for such applications. The plasma produced at atmospheric pressure was with a temperature much higher than 40 ◦ C, and mainly the thermal effects of plasma were used, as in the argon plasma coagulation device [11,12]. Two main requirements are formulated in [1] for the direct application of plasma “on or in the human (or animal) body” and they are the same for treatment in vivo or in vitro of any biological system, including seeds, plants, fresh fruits, etc.: (i) good stability and reproducibility of the plasma source operating at atmospheric pressure in the open space; and (ii) low temperature (

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