Variable Plasma Generator for Low Temperature Sterilizers
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Solution Overview
Problem
Current methods for sterilizing medical instruments using hydrogen peroxide vapor and plasma are inadequate for articles with diffusion-restricted areas, as water vaporizes faster than hydrogen peroxide, leading to condensation barriers and inefficient sterilization, and high concentration hydrogen peroxide poses safety and stability concerns.
Innovation Solution
A novel plasma control method and apparatus that profile the glow discharge plasma power using pulse width modulation and monitoring to minimize etching damage, while concentrating hydrogen peroxide vapor to above 80% by weight before injection into the sterilization chamber, ensuring effective sterilization without handling highly concentrated sterilants.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If hydrogen peroxide vapor is used for sterilization, then sterilization efficacy is improved, but water vapor condenses faster creating barriers that reduce sterilization effectiveness in diffusion-restricted areas
Solution Approach 1:
The patent changes the concentration parameter of hydrogen peroxide vapor from typical levels to above 80% by weight. This high concentration ensures that hydrogen peroxide vapor penetrates diffusion-restricted areas before water vapor can condense and form barriers, resolving the contradiction between sterilization efficacy and condensation barrier formation
Solution Approach 2:
The system performs preliminary concentration of hydrogen peroxide vapor to above 80% before introducing it to the sterilization chamber. This preliminary action ensures that the sterilant reaches diffusion-restricted areas effectively before water condensation can occur, addressing the condensation barrier problem while maintaining sterilization efficacy
2Reliability
If glow discharge plasma power is increased to improve sterilization, then sterilization efficacy is improved, but surface etching damage increases
Solution Approach 1:
The patent applies periodic pulsed plasma discharge instead of continuous high-power plasma. The plasma is delivered in controlled pulses with specific duty cycles, allowing sterilization to occur during active phases while minimizing etching during off phases. This periodic action resolves the contradiction by providing sufficient sterilization efficacy while reducing cumulative surface damage
Solution Approach 2:
The system dynamically adjusts plasma power levels during different phases of the sterilization cycle. Power is modulated based on real-time conditions to optimize sterilization while minimizing etching, transforming the static high-power approach into a dynamic controlled process that balances efficacy and damage prevention
3Reliability
If high concentration hydrogen peroxide is used for sterilization, then sterilization efficacy is improved, but safety and stability concerns increase
Solution Approach 1:
The patent uses an intermediary concentration step where hydrogen peroxide is concentrated to above 80% in a controlled manner within the sterilization chamber rather than introducing highly concentrated material directly. This intermediary approach achieves the necessary sterilization efficacy while avoiding the safety and stability problems associated with handling and introducing very high concentration hydrogen peroxide
Solution Approach 2:
The system replaces mechanical handling of highly concentrated hydrogen peroxide with a vapor-phase concentration process. Instead of physically transporting and managing high-concentration liquid or vapor, the system generates the high concentration in-situ through controlled vaporization and concentration, eliminating the safety hazards associated with handling extreme concentrations
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
This approach enhances the reliability and efficacy of hydrogen peroxide gas plasma sterilization by ensuring thorough penetration of hydrogen peroxide vapor into diffusion-restricted areas, reducing etching damage, and maintaining safety by avoiding the handling of highly concentrated hydrogen peroxide.
Implementation Method 1
The glow discharge (plasma) when activated within the sterilization chamber contributes to the sterilization and decomposes the sterilant at the end of a sterilization program
Implementation Method 2
the combination of hydrogen peroxide vapor diffusing into close proximity with the article to be sterilized together with the reactive particles generated by plasma act together to sterilize the articles
Implementation Method 3
water (H2O) has a higher vapor pressure than hydrogen peroxide (H2O2), and will vaporize faster than hydrogen peroxide from an aqueous solution
Data Source
AI summary
In a low temperature hydrogen peroxide gas plasma sterilizer, plasma within the sterilization chamber contributes to the sterilization process and decomposes the sterilant used at the end of a sterilization programs. The plasma however the must be properly profiled otherwise undesired surface etching may occur on the sensitive medical apparatus. This application describes a novel plasma control method and apparatus which minimize the harmful side effects plasma on the medical apparatus during a sterilization program.