Paper Steam Sterilization Indicator Pack

Resolve Bottlenecks,
Find Innovative Solutions
Generate Solutions

Solution Overview

Problem

The existing Bowie & Dick Test equipment using piled surgical towels is bulky, difficult to handle, and results in dispersion of test results due to thin, low-density non-woven fabrics, leading to incomplete steam penetration and unreliable sterilization indicator sheet coloration.

Innovation Solution

A steam sterilization indicator pack made entirely of paper with a sterilization confirmation indicator sheet sandwiched between steam transmitting adjustment layers of specified thickness and density, allowing for clear discrimination of steam contact areas with a color difference of 10 or more, enhancing test result reliability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If piled surgical towels are used as test equipment for Bowie & Dick Test, then the test can be performed, but the equipment becomes bulky and difficult to handle

Engineering Contradiction:
Improvehandling easeVSAvoidequipment size
Core Design Contradiction:
Ease of operationVSVolume of moving object

Solution Approach 1:

The test equipment is segmented into distinct functional layers: indicator sheet, steam transmitting adjustment layers (with controlled porosity and thickness), and porous body layers. This segmentation allows each component to be optimized independently, resulting in a more compact overall structure while maintaining test functionality.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The invention changes the physical parameters of the test equipment by specifying precise thickness (5-25mm) and density (0.75-0.85 g/cm³) for the steam transmitting adjustment layers, and controlling porosity (80-95%) of the porous body. These parameter changes enable a compact design that is easier to handle while ensuring reliable steam penetration.

Inventive Principle:
Principle #35Parameter changes

2Volume of moving object

If thin non-woven fabrics are used to downsize the test pack, then handling is improved, but test results show dispersion due to incomplete steam penetration

Engineering Contradiction:
Improvepack sizeVSAvoidtest result reliability
Core Design Contradiction:
Volume of moving objectVSReliability

Solution Approach 1:

The invention applies local quality by creating zones with different steam transmission characteristics. The steam transmitting adjustment layers have controlled porosity (80-95%) and thickness to regulate steam flow, while the indicator sheet provides visual feedback. This localized control ensures uniform steam penetration throughout the compact structure, eliminating test result dispersion.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The test pack uses composite material structure combining paper-based indicator sheet, cellulose or synthetic fiber steam transmitting adjustment layers with specific density and porosity characteristics, and porous body layers. This composite approach ensures adequate steam penetration while maintaining a compact, handleable size.

Inventive Principle:
Principle #40Composite materials

3Device complexity

If non-uniform porous body is used in the test pack, then the structure is simpler, but the indicator sheet shows non-uniform coloration making results unreliable

Engineering Contradiction:
Improvestructure complexityVSAvoidcoloration uniformity
Core Design Contradiction:
Device complexityVSManufacturing precision

Solution Approach 1:

The invention applies preliminary action by pre-configuring the steam transmitting adjustment layers with controlled porosity (80-95%) and thickness (5-25mm) before the sterilization process. This preliminary structuring ensures uniform steam distribution during the test, resulting in uniform coloration of the indicator sheet and reliable test results without requiring complex post-processing.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The invention changes the porosity parameter of the porous body to a controlled range (80-95%) and specifies thickness parameters for the steam transmitting adjustment layers. These parameter changes ensure uniform steam penetration through the pack, producing consistent coloration across the indicator sheet while maintaining structural simplicity.

Inventive Principle:
Principle #35Parameter changes

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 paper-based steam sterilization indicator pack improves handling and reduces test result dispersion by ensuring uniform steam penetration and clear visualization of steam contact areas, thus enhancing the reliability of the Bowie & Dick Test.

Implementation Method 1

The sterilization confirmation indicator sheet, on which patterns which may color or discolor due to contacting with steam are printed

Methodology Applied
Scientific EffectThermal-metachromasy: Thermochromism

Implementation Method 2

steam transmitting adjustment layers which are formed to have specified thickness by stacking the steam transmitting adjustment paper sheets having specified density

Methodology Applied
Scientific EffectPermeation: Permeation

Implementation Method 3

steam transmitting adjustment layers formed to have specified thickness by stacking the steam transmitting adjustment paper sheets having specified density

Methodology Applied
Scientific EffectPorosity: Porosity

Implementation Method 4

After heating is carried out at 134°C for 3.5 minutes, the coloring or discoloring state of the indicator sheet is observed

Methodology Applied
Scientific EffectConduction (thermal): Conduction (thermal)

Implementation Method 5

pressurized steam is provided in the autoclave to sterilize the materials

Methodology Applied
Scientific EffectConvection: Convection

Data Source

PatentEP2774627B1Steam sterilization indicator pack
Publication Date: 2017.09.20 NICHIYU GIKEN KOGYO CO LTD
  • EP2774627B1 patent drawingFigure 1~2
  • EP2774627B1 patent drawingFigure 3(a)~3(b)
  • EP2774627B1 patent drawingFigure 4~5

AI summary

Provided is a simplified steam sterilization indicator pack that is able to improve reliability of Bowie & Dick Test, and also is able to be downsized and improves handling. A steam sterilization indicator pack comprises: a pack which accommodates a sterilization confirmation indicator part that comprises steam transmitting adjustment layers 20, 20, of which total thickness is 5-25mm, arranged so as to sandwich a sterilization confirmation indicator sheet 22 applying a printed pattern which colors or discolors due to contacting with steam, in a paper container 12 that passes steam more than the steam transmitting adjustment layers, and the steam transmitting adjustment paper sheets 18 include a sheet that has at least a density of 0.75g/cm3 so that in a case where pressurized steam is introduced at 134 °C for 3.5 minutes in a vacuumed autoclave into which the pack is put and residual air remains in the autoclave, portions of the patterns of the sterilization confirmation indicator sheet 22 that finish discoloring and other portions thereof that do not discolor can be differentiated with the naked eye.