Fabrication of the Plasma-Chemical Indicator Strip for the Detection of Plasma Processing Effects

In order to confirm the plasma processing effect at a required point by visual observation, the plasma-chemical indicator (PCI) was fabricated. PCI is the piece of PET (polyethylene terephthalate) sheet strip on which a color indication mark which is sensitive and distinguishable to H2O2 and O2 plasma was printed. The distinguishable property on PCI between H2O2 and O2 plasma was realized by mixing two different colorants: red azo-dye and green phthalocyanine pigment were mixed into nitro cellulose resin. When PCI is treated by H2O2 and H2O plasma, the color is continuously shifted from the purple of control PCI toward dull light green and light bluish green respectively after 15 minutes of treatment time. However, when the PCI is treated by O2 plasma, it also continuously shifted toward a pinkish color after 15 minutes of treatment time. Therefore, it could be said that this prepared PCI is sensitive and distinguishable to H2O2 and O2 plasma. Finally it is discovered that not only final color, but also the color in the middle of the change can also be available as PCI.