22 May 2022

It is capable of generating three jets of non-thermal plasma simultaneously, providing a large plasma contact area of 1 sq. cm

Scientists at the Immanuel Kant Baltic Federal University (IKBFU), together with their colleagues from France and Colombia have conducted research that has allowed them to create a compact device that accelerates medical procedures using non-thermal plasma. Immanuel Kant Baltic Federal University (IKBFU) press service announced this on Tuesday.

Plasma is an ionized gas composed of electrons and positively charged ions. There is also such a thing as "cold plasma," characterized by the low temperature of its electrons. However, the general or gas temperature, in the usual sense, can be high. For example, the plasma of a lit candle is considered cold, but its gas temperature exceeds 1,000 degrees Celsius. Yet, it is also possible to produce a plasma with the temperature of the electrons remaining high and the temperature of the positive ions being quite low. The term "non-thermal" is used for this kind of plasma. There are now many ways to generate non-thermal plasma with a gas temperature of 40 degrees Celsius, which can be used to treat skin and even on open wounds without any pain, the press service explained.

Thanks to research at the Immanuel Kant Baltic Federal University's Optical Radiation Laboratory, a compact device capable of generating three jets of non-thermal plasma simultaneously was developed, which provided a large plasma contact area of 1 square centimeter. This was achieved through a special electrode system design and a special discharge ignition mode.

"If we compare our device with its analogues, PlasmaDerms VU-2010 by a German company called CINOGY GmbH comes to mind, or Helios by a Russian company called NPC Plasma LLC, but the advantages of our device are obvious. Since the mentioned devices have plasma generated in the form of a thin needle, the area of contact of the jet with the patient's skin does not exceed 3 sq. mm, in addition, helium consumption in our device is three times lower. The large contact area of the plasma is necessary to reduce the time of the physiotherapy procedure and to reduce the consumption of working gas".

 Helium jet non-thermal plasma contains a stream of charged particles, when interacting with air particles, chemically active radicals are produced, as well as ozone generation and shortwave ultraviolet radiation. All these factors can quickly and painlessly destroy pathogenic bacteria or viruses and heal wounds without the use of antiseptics or antibiotics. Nonthermal plasma is also known to have a unique ability to rejuvenate skin.

Exploring optimal conditions for generating non-thermal plasma

Scientific research was required to develop new medical equipment generating a stream of non-thermal plasma with the desired characteristics.

IKBFU scientists and their French colleagues searched for optimal conditions in terms of minimal gas temperatures and the flow rate of helium used as a working gas. In the course of several scientific visits to the Laplace laboratory of the National Polytechnic Institute of Toulouse, a unique research unit was developed, which automatically recorded more than a dozen parameters of the generated plasma at the same time. "By analyzing the array of obtained experimental data, we were able to identify the conditions for achieving the optimal mode for generating a jet of non-thermal plasma," IKBFU noted. 

The plasma flux can be characterized by its geometric dimensions and some parameters of the plasma itself, the main one being the concentration of electrons. Therefore, the second work was devoted to the development of a non-contact and automated method to estimate the electron concentration in the generated non-thermal plasma flux.

The development of the optical method for diagnosing gas-discharge plasma was conducted at the IKBFU Coherent-optical Measuring Systems Laboratory under the supervision of Igor Alexeenko, Head of the laboratory. The laser beam passed through a jet of non-thermal plasma and numerous elements of the optical circuitry of the setup and fell into the lens of a digital camera. Thus, an interference picture was obtained, where the electron concentration and its distribution over the volume of the plasma jet were estimated by the distance between the fringes and their shape.

The results of the study were published in Plasma and AppliedScience of the journal MDPI (Switzerland).