Plasma Sterilization Indicator with Azo Dye
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Solution Overview
Problem
Existing indicators for cold plasma sterilization with hydrogen peroxide gas do not effectively change color and lack stability, making it difficult to confirm whether sterilization is complete and proper, especially when compared to ethylene oxide gas and heat sterilization methods.
Innovation Solution
A novel indicator using an azo dye with a heterocyclic ring, a mercapto or dithiocarbamyl group, and a specific resin binder, which changes color clearly upon plasma sterilization and maintains stability under high humidity conditions, allowing for effective confirmation of sterilization completion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If existing indicators for cold plasma sterilization are used, then the sterilization process can be performed, but the color change is not clear and the indicator lacks stability under high humidity conditions
Solution Approach 1:
The patent modifies the chemical parameters of the indicator by using specific azo dyes with heterocyclic rings (thiazole, benzothiazole, thiadiazole, triazole, pyridine, or quinoline) combined with mercapto or dithiocarbamyl groups. This chemical parameter change enables clear color transformation from yellow to blue upon plasma sterilization while maintaining stability under high humidity conditions, directly resolving the contradiction between reliability and measurement precision.
2Loss of information
If existing indicators are used, then the sterilization can be performed, but it is difficult to confirm whether sterilization is complete and proper
Solution Approach 1:
The patent employs a color change mechanism where the indicator transforms from yellow to blue upon exposure to cold plasma sterilization. This visual color change provides clear and unambiguous information about sterilization completion and effectiveness, eliminating the loss of information and enabling precise sterilization detection without requiring complex instrumentation.
3Stability of the object's composition
If existing indicators are used, then the sterilization process can proceed, but the color tone reverts or fades making confirmation difficult
Solution Approach 1:
The patent creates a composite indicator system combining specific azo dyes with heterocyclic rings and mercapto or dithiocarbamyl groups. This composite material structure ensures that the color change produced during plasma sterilization remains stable and does not revert or fade, maintaining both color tone stability and sterilization confirmation reliability throughout the sterilization process and afterward.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The indicator provides a clear and stable color change after sterilization, ensuring proper sterilization confirmation and maintaining color tone stability, even under high humidity, unlike existing indicators which often revert or fade.
Implementation Method 1
the color of the basic dye is brought into fading as a result of the oxidative decomposition of the basic dye owing to oxidation power of the hydrogen peroxide vapor or of the plasma formed from the hydrogen peroxide vapor
Implementation Method 2
the color of the dye is brought into changing as a result of the ring-opening of the lactone ring in the dye to change to a colored rhodamine dye owing to oxidation power of the hydrogen peroxide vapor or of the plasma formed from the hydrogen peroxide vapor
Data Source
AI summary
The disclosed is a novel indicator for plasma sterilization which utilizes an azo dye which has been known and used for preparing indicator for ethylene oxide gas sterilization and indicator for heat sterilization, and which exhibits a quick change of color upon the cold plasma sterilization process with using a oxidizing gas such as hydrogen peroxide, the change of color being indicated as a clear change of the color tone. The azo dye which has been known and used for preparing indicator for ethylene oxide gas sterilization and indicator for heat sterilization is used in combination with a compound containing a mercapto group or a dithiocarbamyl group therein as the compound capable of reacting with the azo dye upon the plasma sterilization treatment, and thereby bringing discoloration into the azo dye. Moreover, in combination with them, a polyhydric phenol compound or an aromatic carboxylic acid may be further used as antifading agent for discolored azo dye which is produced during the plasma sterilization process in order to stabilize the occurrence of discoloration.