Interaction of atmospheric plasma jet with living tissue

Summary form only given. Recently a great attention is attracted to creation of the cold plasma jets and their interaction with living tissue. The plasma gun operating on helium and equipped with high-voltage resonant transformer is designed (up to 10 kV, frequency ~30 kHz). The gun is equipped with pair of high voltage electrodes - central electrode (which is isolated from the direct contact with plasma by ceramics) and outer ring grounded electrode. Long nondivergent plasma jets with length more than 5 cm and diameter 1-2 mm are obtained. The electrical current measurements indicate that discharge current appeared for applied voltages U higher than threshold value of about 1 kV. Near to the threshold discharge current appeared as two peaks in the moments corresponded to maximum and minimum of the applied high voltage, while increase of U results in shift of discharge current peaks to the earlier times (up to quarter of period for U>3 kV). Value of current in peak increased with applied voltage (~8 mA for U=3 kV). Part of the discharge current is closing through the plasma jet: peak of current through the jet did not exceed 1 mA and appeared once in each period (when central electrode is at positive potential). The exposition of the living tissue to the helium plasma jet causes different types of cellular response. Experimental results indicate that the response of live cells to plasma jet can be classified in accordance with intensity of treatment (intense, medium and mild). At mild level of treatment the migration rate of cells is decreased, at medium level cells are detached from the extracellular matrix, and at intense treatment the protecting media is pressing out and cells dies most likely by desiccation in the uncovered by media region. It should be noted that similar effect of desiccation may be reached by helium flow only (no plasma), however it requires increase of the gas feeding by a factor of 2 in comparison with the case with plasma.