Measurement of NO₂- penetration concentration in surface microdischarge treated model tissue, based on image processing technology

Plasma has a wide range of applications in the medical field. The reactive oxygen species and reactive nitrogen species generated by plasma play a major role during the plasma treatment. However, the measurement of penetration concentration of reactive species into tissues has always been a major problem in the application of plasma medicine. In this paper, based on the digital image processing technology, we realized the measurement of $\mathrm{NO}_{2}^{-}$ penetration concentration inside model tissues by SMD treatment. Firstly, based on the specific color reaction of Griess and $\mathrm{NO}_{2}^{-}$, the multivariate linear relationship between image color and standard concentration was established. Then, the model tissues were treated by SMD under different time and treating distance. Finally, the concentration of each point in each layer of the model tissue under SMD treatment was measured and calculated. It is found that the $\mathrm{NO}_{2}^{-}$ concentration distribution in the central part of each layer was uniform under SMD treatment, and the concentration gradually decreased with the penetration depth. This study offers a fast and smart diagnostic method for reactive species amount into tissue and provide data for clinic as well as numerical modeling investigation.