## 3 Results
### Determination of the Effective Treatment Area
Figure 6: Alteration of (**a**) width, (**b**) length and (**c**) total area depending on incidence angle (0\({}^{\circ}\), 25\({}^{\circ}\), 50\({}^{\circ}\)) and plasma treatment time (30, 45 and 60 s) of inoculated agar plates (_Staphylococcus aureus_ DSM 799/ATCC 6538) with kINPen® MED-\(\beta\) (M \(\pm\) SD, \(n\) = 6). After the visualization of the biological effective area for the kINPen® MED-\(\beta\), the question arose if this shape–in particular, the elliptical shape–of the inhibition zone during tilted treatment can be correlated with a non-biological parameter (Figure 5b). Therefore, the reactive oxygen species (ROS) and (vacuum) ultraviolet (V)UV distribution on the treated surface was analyzed with regard to the influence of the incidence angle on the shape of the effective area on a treated surface. Figure 8: Effective (**a**) width and (**b**) length of the inhibition zones in the antimicrobial assay (_Staphylococcus aureus_ DSM 799/ATCC 6538, M \(\pm\) SD, \(n\) = 6) and the ROS determination (M \(\pm\) SD, \(n\) = 3) of primary, secondary and peripheral zones depending on incidence angle (0\({}^{\circ}\), 25\({}^{\circ}\), 50\({}^{\circ}\)) after 45 s treatment with kINPen® MED-ß. Figure 7: Effective treatment area of kINPen® MED-ß visualized by starch-potassium iodide plates at 8.5 mm distance after 45 s plasma treatment for (**a**) perpendicular treatment and (**b**) an incidence angle of 50\({}^{\circ}\) (side 1: inclination of the kINPen® MED-ß as shown in Figure 2c, side 2: area with plasma plume propagation) and (**c**,**d**) analyzed according to primary (green), secondary (blue) and peripheral (red) zones. The width of the effective zones increased by 23% in the case of VUV and remained stable for UV, whereas the length remained stable for VUV and decreased by 19% for UV with a rising incidence angle of the kINPen(r) MED-\(\beta\) (Figure 11a,b). The total area of VUV was smaller compared to UV because of the strong absorption within the ambient air outside the argon gas-containing plasma  
Figure 10: (**a**) VUV and (**b**) UV irradiation profile for an incidence angle of 60\({}^{\circ}\) (side 1: inclination of the kINPen® MED-\(\beta\) as shown in Figure 2c, side 2: area with plasma plume propagation) and (**c,d**) analyzed according to primary (green), secondary (blue) and peripheral (red) zones. Figure 9: Total effective area depending on incidence angle (0\({}^{\circ}\), 25\({}^{\circ}\), 50\({}^{\circ}\)) after 45 s treatment with kINPen® MED-\(\beta\) for the inhibition zone assay (_Staphylococcus aureus_ DSM 799/ATCC 6538, M \(\pm\) SD, \(n=6\)) and ROS determination (M \(\pm\) SD, \(n=3\)). effluent (Figure 11c). Additionally, the total area of the UV radiation zone decreased by 21%, whereas the size of the VUV zone was independent of the incidence angle. The total area of the inhibition zones (_S. aureus_) increased (Figure 6c), whereas UV slightly decreased and VUV remained stable with rising incidence angle (Figure 12). Figure 11: Alteration of (**a**) width, (**b**) length and (**c**) total area of VUV and UV irradiation caused by kINPen® MED-\(\beta\) after perpendicular (0\({}^{\circ}\)) and tilted (5–60\({}^{\circ}\)) application visualized by fluorescence dyes. Figure 12: Total effective area depending on incidence angle (0\({}^{\circ}\), 25\({}^{\circ}\), 50\({}^{\circ}\)) with kINPen® MED-\(\beta\) for the inhibition zone assay (after 45 s treatment; _Staphylococcus aureus_ DSM 799/ATCC 6538, M \(\pm\) SD, \(n=~{}6\)) as well as VUV and UV.