Chitosan Hydrophilization of Sensor Cartridge Channels

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Solution Overview

Problem

The formation of gas bubbles in measuring channels of sensor cassettes due to non-uniform internal surfaces with different wetting properties leads to incomplete filling and inaccurate measurements during the determination of gaseous analytes in aqueous liquids, particularly in automated analyzers, where existing solutions require complex factory-based coating processes or are not suitable for sensor elements.

Innovation Solution

A method involving the use of a chitosan or chitosan derivative solution with a pH value between 6.4 and 6.8 is introduced into the measuring channel, followed by a liquid with a higher pH, allowing the chitosan to deposit on the surfaces and hydrophilize them, which can be done easily by the user or automatically, without the need for extensive pretreatment, and can be repeated as needed.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a complex factory-based coating process with plasma treatment and multiple reagent solutions is used to hydrophilize surfaces, then the wetting properties are improved, but the device complexity and ease of operation deteriorate

Engineering Contradiction:
Improvewetting propertiesVSAvoidcoating process complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent extracts the essential function of hydrophilization by using only chitosan solution without the complex plasma treatment and multiple reagent solutions required by conventional methods. This simplifies the process while maintaining the wetting property improvement.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The patent changes the chemical parameters by using chitosan solution with specific pH values (6.4-6.8 for deposition, higher pH for washing). This parameter optimization allows simple solution-based hydrophilization without complex physical-chemical pretreatment processes.

Inventive Principle:
Principle #35Parameter changes

2Reliability

If plasma treatment and graft polymerization are used to create hydrophilic surfaces, then the surface wetting is improved, but the ease of operation deteriorates due to coordinated process steps

Engineering Contradiction:
Improvesurface wettingVSAvoiduser operation simplicity
Core Design Contradiction:
ReliabilityVSEase of operation

Solution Approach 1:

The chitosan solution automatically deposits on the measuring channel surfaces through simple pH-controlled treatment, eliminating the need for coordinated plasma treatment and graft polymerization steps. The process self-regulates through the pH differential between deposition and washing solutions.

Inventive Principle:
Principle #25Self-service

3Reliability

If multiple reagent solutions and chemical reaction steps are used in factory coating processes, then the hydrophilization is achieved, but the ease of manufacture and operation worsen

Engineering Contradiction:
ImprovehydrophilizationVSAvoidmanufacturing simplicity
Core Design Contradiction:
ReliabilityVSEase of manufacture

Solution Approach 1:

The patent segments the hydrophilization process into two simple steps: (1) treatment with chitosan solution at pH 6.4-6.8 for deposition, and (2) washing with solution at higher pH. This segmentation eliminates the need for complex multi-stage factory coating processes.

Inventive Principle:
Principle #1Segmentation

4Manufacturing precision

If physical-chemical pretreatment is performed before polymer film application, then the surface preparation is improved, but the ease of operation deteriorates

Engineering Contradiction:
Improvesurface preparationVSAvoidoperation simplicity
Core Design Contradiction:
Manufacturing precisionVSEase of operation

Solution Approach 1:

The patent eliminates the need for physical-chemical pretreatment by directly using pH-controlled chitosan solution treatment. The pH parameter control (6.4-6.8 for deposition, higher for washing) provides sufficient surface preparation without complex pretreatment steps.

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

This approach effectively reduces the formation and adhesion of gas bubbles, improving the hydrophilic surface properties of the measuring channel, ensuring reliable filling and measurement processes without impairing the sensor function, and can be maintained throughout the use of the sensor cassette.

Implementation Method 1

A method is proposed here in which the value of the electrical resistance is measured between at least two points in the measuring chamber, the filling process of the measuring chamber being controlled depending on the determined size of the measured resistance.

Methodology Applied
Scientific EffectAdsorption: Adsorption

Implementation Method 2

Gas bubbles form in particular when there are non-uniform internal surfaces within the measuring channel of the sensor cassette, which have different wetting properties by liquids.

Methodology Applied
Scientific EffectWetting: Wetting

Data Source

PatentEP2595752B1Method for hydrophilising surfaces of fluid components and analysator with fluid packs using the method
Publication Date: 2018.08.22 F HOFFMANN LA ROCHE & CO AG
  • EP2595752B1 patent drawingFigure 1~3
  • EP2595752B1 patent drawingFigure 4~5

AI summary

The invention relates to a method for at least partially applying a hydrophilic polymer to a measurement channel of a sensor cartridge that can be replaceably inserted in an analyzer, said measurement channel comprising at least one sensor element. The method is characterized in that a sensor cartridge is inserted in the analyzer, an aqueous solution containing chitosan or a chitosan derivative is introduced in the measurement channel of the sensor cartridge, and following a residence time the aqueous chitosan solution is replaced with a gaseous or liquid medium, wherein residues of the chitosan or chitosan derivatives remain on the inside surface of the measurement channel and hydrophilize said surface.