Sterilization Indicator With Variable Wicking Zones

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Solution Overview

Problem

Current sterilization indicators for steam sterilization lack effective control over temperature and time parameters, leading to potential false indications of adequate sterilization, and are often costly, time-consuming, and prone to batch variations.

Innovation Solution

A compact sterilization indicator with a thermally conductive base element, a wicking element having distinct zones for controlled wicking rates, and a temperature-sensitive chemical composition that indicates acceptable sterilization by wicking beyond a marker after a sterilization process, ensuring accurate integration of time and temperature criteria.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If spore strips or samples are used for sterilization control, then accurate sterilization verification is achieved, but excessive cost and batch to batch variation occur

Engineering Contradiction:
Improvesterilization verification accuracyVSAvoidbatch to batch consistency
Core Design Contradiction:
Measurement precisionVSReliability

Solution Approach 1:

The patent replaces expensive, variable spore strips with a disposable chemical indicator strip containing a fusible material and wicking strip. This chemical-based indicator is cheaper to manufacture, eliminates batch-to-batch biological variation, and provides consistent performance across production lots while maintaining sterilization verification capability.

Inventive Principle:
Principle #27Cheap short-living objects (Disposable)

Solution Approach 2:

The patent substitutes the biological spore-based system with a chemical system using fusible material that melts at a specific temperature and wicks along a wicking strip. This mechanical-chemical replacement eliminates the biological variability inherent in spore preparations while maintaining the temperature-sensitive indication function.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

2Manufacturing precision

If chemical indicators with controlled wicking rates are used, then temperature and time parameters are well controlled, but device complexity increases

Engineering Contradiction:
Improvetemperature and time parameter controlVSAvoidindicator structure complexity
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent applies local quality by creating zones of different wicking rates along the wicking strip. The wicking strip is divided into sections with progressively slower wicking characteristics, allowing the indicator to integrate temperature and time exposure in a controlled manner. This localized variation in wicking properties enables precise sterilization parameter verification without requiring complex electronic or mechanical systems.

Inventive Principle:
Principle #3Local quality

3Reliability

If long sterilization times are used, then confidence in steam penetration is increased, but time economy and energy consumption worsen

Engineering Contradiction:
Improvesteam penetration confidenceVSAvoidsterilization cycle efficiency
Core Design Contradiction:
ReliabilityVSProductivity

Solution Approach 1:

The patent implements feedback by providing immediate visual indication through the wicking strip that shows whether sterilization parameters have been met. The color change and wicking distance provide real-time confirmation of adequate steam penetration and exposure, eliminating the need for extended sterilization times based on conservative defaults. This feedback mechanism allows optimization of sterilization cycles for both reliability and efficiency.

Inventive Principle:
Principle #23Feedback

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 solution provides a cost-effective, accurate, and reliable indication of proper steam sterilization, ensuring that sterilization criteria are met with a margin of safety, reducing the risk of false positives and batch variations.

Implementation Method 1

a wicking element (20) positioned at least in part in contact with the indicator chemical composition and positioned at least in part within the recess

Methodology Applied
Scientific EffectCapillary action: Capillary Action

Implementation Method 2

a base element (16) formed from a thermally conductive material

Methodology Applied
Scientific EffectThermal conduction: Conduction (thermal)

Data Source

PatentEP3445410B1Sterilization indicator
Publication Date: 2023.07.05 AMERICAN STERILIZER CO
  • EP3445410B1 patent drawingFigure 1~4

AI summary

A compact sterilization indicator includes a wicking element having at least two different wicking rates across the length of the wicking element.