# Applications of Plasma Produced with Electrical Discharges in Gases for Agriculture and Biomedicine
## 2 Plasma as a Medium for Application in Agriculture and Biomedicine
### Biomedical and Health Protection Problems  
Over the last two decades of this century, plasma technologies have been used to detect, prevent, and solve many problems related to health protection. These include hygiene problems, especially hospital hygiene and related viral and bacterial diseases, mycoses and skin diseases, chronic and senile diseases, dental care, cosmetology, tissue engineering, and medical diagnostics [22; 30; 37; 62; 65; 68; 69; 70; 71; 75; 76; 85; 86; 87].  
The effects of plasma on biological material (tissues, skin, viruses, bacteria, and fungi) result from three basic techniques: direct plasma, indirect interaction, and a hybrid technique [88]. The direct interaction of plasma is based on the fact that a living organ/tissue plays the role of one of the plasma rector electrodes. Most often, the voltage is not directly connected to the living tissue, but some current may flow through it in the form of a small forward current, a displacement current, or both, because tissues have conductive and dielectric properties. The conduction current is usually limited to avoid thermal effects or electrical stimulation of the muscles. Such treatment makes it possible to use the influence of active and uncharged atoms and molecules, as well as ultraviolet (UV) radiation, on the surface of living tissue. The most important feature that distinguishes direct plasma treatment is that a significant stream of charges reaches the surface of the living tissue. The indirect (\"current free\") plasma interaction mainly uses the uncharged atoms and molecules that are produced in the plasma and involves little, if any, flux of charges to the surface. The plasma generated between the two electrodes is transported to the application area by a gas stream (argon, helium, and oxygen). Various devices are used here, including very narrow devices, such as so-called plasma needles for larger plasma torches. An advantage of indirect treatment may be that the plasma device is always at a distance from the surface to be treated, so that there is no current flowing through the tissue. Hybrid plasma treatment combines both direct and indirect plasma generation techniques. The discharges used in the hybrid method are called barrier corona discharge (BCD) [60; 88]. This is achieved by introducing a grounded mesh electrode on one of the electrodes, which has much lower electrical resistance than the skin. As a result, virtually all the electric discharge current flows through the mesh electrode. The listed techniques of non-thermal plasma treatment allow for a certain degree of fine-tuning of its properties to a given medical process. Thus, the amount of nitric oxide (NO) can be fine-tuned compared with the ozone (O\({}_{3}\)) produced in the plasma. It is also possible to influence the microstructure of the plasma discharge, which may be of particular importance in direct treatment [89]. The direct plasma treatment technique involves a significant charge flux, which provides greater flexibility in fine-tuning the non-thermal effects of the generated plasma for medical applications.