Ethylene Oxide Sensor with Acid Sorbent for Sterilization Monitoring
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Solution Overview
Problem
The ethylene oxide (EO) sterilization process is time-consuming due to the slow aeration of the chamber, leading to incomplete sterilization of items, especially when the chamber is packed to capacity, and existing sensors are either expensive or subjective in determining sterilization completion.
Innovation Solution
The development of ethylene oxide sterilization sensors that include a heat-shrinkable film and an acid-functional porous sorbent, where the acid has a boiling point above 120°C and a pKa of no greater than 2.5, which generates thermal energy upon interaction with ethylene oxide, causing the film to shrink and indicating proper sterilization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the chamber is packed to maximum capacity during sterilization, then the turnover rate of materials needing sterilization is improved, but the aeration time becomes excessively long and some items may not receive full exposure to EO
Solution Approach 1:
The patent places multiple sterilization sensors throughout the chamber before the sterilization cycle begins. These sensors pre-map the chamber's sterilization zones and identify areas that may not receive adequate EO exposure, allowing for proactive adjustment of the sterilization process to ensure complete coverage even when the chamber is packed to capacity.
Solution Approach 2:
The sterilization sensors continuously monitor EO concentration and exposure levels throughout the chamber during the sterilization and aeration processes. This real-time feedback allows the system to detect when all sensor locations have achieved sufficient sterilization exposure, enabling earlier termination of the aeration process and reducing overall cycle time while ensuring complete sterilization.
2Measurement precision
If biological indicators are used to ensure reliable sterilization indication, then the accuracy of sterilization detection is improved, but the cost and time required for analysis increases significantly
Solution Approach 1:
The patent replaces biological indicators with electronic sterilization sensors that detect EO concentration and exposure levels through electronic means. These sensors provide immediate digital readings of sterilization parameters, eliminating the need for manual collection, incubation, and analysis of biological indicators, thus reducing analysis time from hours to minutes while maintaining detection accuracy.
Solution Approach 2:
The sterilization sensors create an electronic copy or representation of the sterilization exposure conditions at multiple locations throughout the chamber. By monitoring EO concentration and exposure time at these sensor locations, the system obtains reliable indication of sterilization completion without requiring physical biological indicator tubes to be processed later.
3Ease of manufacture
If colorimetric stickers are used for sterilization indication, then the cost is reduced, but the objectivity and reliability of sterilization determination deteriorates due to subjective color perception
Solution Approach 1:
The patent replaces subjective visual color assessment with objective electronic sensors that measure EO concentration and exposure parameters quantitatively. These sensors provide numerical data regarding sterilization exposure, eliminating human variability in color perception and interpretation while maintaining cost-effectiveness compared to biological indicators.
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 sensors provide a reliable, objective, and cost-effective means to ensure complete sterilization by visually indicating the completion of the EO sterilization process, reducing the time required for chamber aeration and enhancing the consistency of sterilization across the chamber.
Implementation Method 1
an acid-functional porous sorbent in thermal contact with the heat-shrinkable film
Implementation Method 2
This sensor utilizes an exothermic interaction between ethylene oxide and the acid in contact with the porous (high surface area) sorbent. The heat generated from the interaction causes a dimensional change in the heat-shrinkable film.
Implementation Method 3
The heat generated from the interaction causes a dimensional change in the heat-shrinkable film. The shrinkage of the heat-shrinkable film, as a result of this activation by ethylene oxide, is what indicates proper sterilization.
Data Source
AI summary
An ethylene oxide sterilization sensor, and method of use, wherein the sensor includes: a heat-shrinkable film; an acid-functional porous sorbent in thermal contact with the heat-shrinkable film; and an acid having a boiling point above 120° C. and a pKa of no greater than 2.5, wherein the acid is impregnated in or covalently attached to the porous sorbent.