Fabrication of the Plasma-Chemical Indicator and It’s Application

Abstract

In order to confirm the plasma processing effect at a required point by visual observation, the plasma-chemical indicator (PCI) was fabricated. In this research, the effects of NC and PA on discoloration properties of PCI was examined, since the color of prepared printing ink was fairly affected by the kind of binder. Viscosity effects of these binders on the sensitivity of PCI were also investigated. As an Application of PCI, the 3D mapping was created by the color difference E*ab obtained by 15 min of H O plasma irradiation using 25 pieces of PCI. 2 It was found that the influence of viscosity on change of color is small, comparing with the influence by the kind of binder. The expansion effect of an indicator range was able to be confirmed for H 2 O and H 2 O 2 plasma, but not for O 2 plasma. The optimal mixing ratio of NC and PA for H 2 O and H 2 O 2 plasma was 5 and 15 wt/wt, respectively. 3D mapping which visualized the situation was well in agreement with the visual observation results.

Sterilization Effects of HO₂/O₂^- Radicals Produced by H₂O-O₂ Plasma

“…The color of PCI shifted toward green when the PCI made contact with the radicals such as ･OH, ･O and ･O 2 -. Whereas it is shifted toward red when the PCI made contact with O 2 ( 1  g ) [7,8]. The reactor is equipped with a 8.8-L bell-jar made of stainless steel in which parallel disk-electrodes are set.…”

“…On the other hand, the resultant color of red in 100 Pa for O 2 plasma is explained by the ease of decomposing of green pigment in PCI against the action of O 2 ( 1  g ) [7,8]. As shown in Figure 8, the color of PCI after H 2 O 2 -O 2 plasma irradiation start is shifting in the green direction of -a, and it turns out that the time which showed the clearest green is 3 minutes after the start of plasma irradiation.…”

“…The resultant color of green in both case of H 2 O and O 2 plasma is considered to be the action of ･ OH for H 2 O plasma and ･O for O 2 plasma, and it is explained by the ease of decomposing of red dye in PCI against radical [7,8]. On the other hand, the resultant color of red in 100 Pa for O 2 plasma is explained by the ease of decomposing of green pigment in PCI against the action of O 2 ( 1  g ) [7,8].…”

“…In our previous report [7,8], in order to confirm the plasma processing effect at a required point by visual observation, PCI was fabricated. The relation between the resultant color of PCI and interactions with H 2 O and O 2 plasmas are shown in Table 3.…”

Plasma-Chemical Indicator and It’s Color Changes by Oxygen Plasma

“…In a previous report [1,2], the sensitivity of PCI was distinguishable to 30% H 2 O 2 and O 2 plasma was fabricated by screen printing on a PET sheet using printing ink prepared on the bases of composition of ordinary gravure ink in which two different colorants, red azo-dye (Az-R) and green phthalocyanine pigment (Ph-G) and nitro cellulose (NC) and polyamide (PA) resins as binder were used. When the PCI was exposed to H 2 O 2 and H 2 O plasma, the color continuously shifted from the purple of control PCI toward dull light green and light bluish green respectively during 15 minutes of processing time with the action of •OH.…”