ISE Half-Cell Membrane Dip-Coating and Segmented Hollow Body

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Solution Overview

Problem

Ion-selective electrodes (ISE) face issues with membrane stress and leakage due to non-positive fits and softener leaching, leading to measurement inaccuracies over time.

Innovation Solution

A method for producing ISE membranes involves immersing a hollow body into a polymer solution, drying to form a membrane, and optionally applying surface modifications and support structures to ensure a positive and stress-free attachment, enhancing adhesion and mechanical stability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If clamping devices are used to compensate for membrane settling and shrinking, then measurement reliability is improved, but device complexity and manufacturing cost increase

Engineering Contradiction:

Improvemeasurement reliabilityVSAvoidclamping device complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The hollow body is divided into two separable parts: a first hollow body portion that forms the membrane support structure and a second hollow body portion that forms the sealing structure. This segmentation allows each part to be optimized independently for its specific function while simplifying the overall device design compared to complex integrated clamping mechanisms.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The second hollow body portion is inserted into the first hollow body portion to form the complete hollow body. This nested arrangement allows the sealing structure to be integrated within the support structure, eliminating the need for external clamping devices while maintaining measurement reliability.

Inventive Principle:

Principle #7Nested doll (Nesting)

2Ease of manufacture

If non-positive fit clamping is used for membrane installation, then ease of manufacture is improved, but membrane stress and leakage increase

Engineering Contradiction:

Improvemembrane installation easeVSAvoidmembrane sealing reliability

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The membrane is formed with a curved surface that conforms to the curved inner surface of the hollow body. This curved geometry creates a positive fit between the membrane and the hollow body, ensuring reliable sealing while maintaining ease of manufacture through the dip-coating process.

Inventive Principle:

Principle #14Spheroidality (Curvature)

Solution Approach 2:

The membrane is formed as a flexible thin film through dip-coating of the hollow body in a polymer solution followed by drying. This flexible film conformally adheres to the hollow body surface, creating a stress-free positive fit that prevents leakage while simplifying manufacturing.

Inventive Principle:

Principle #30Flexible shells and thin films

3Stability of the object's composition

If softener leaching is allowed to occur in the membrane, then membrane flexibility is maintained, but membrane shrinking and bypass formation increase

Engineering Contradiction:

Improvemembrane flexibilityVSAvoidmembrane integrity

Core Design Contradiction:

Stability of the object's compositionVSReliability

Solution Approach 1:

The membrane is formed as a composite material containing the polymer matrix, ionophore, and softener in specific proportions. This composite structure maintains membrane flexibility while the controlled formulation prevents excessive softener leaching and subsequent membrane shrinking that would cause bypass formation.

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The membrane composition parameters are optimized by controlling the ratios of polymer, ionophore, and softener, as well as the dip-coating parameters such as solution concentration and drying conditions. These parameter changes ensure the membrane maintains flexibility without excessive softener leaching that would lead to shrinking and bypass formation.

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 method simplifies the production of ISE half-cells with improved membrane attachment and stability, reducing leakage and maintaining measurement accuracy over time.

Implementation Method 1

drying the hollow body and evaporating the solvent from the membrane solution

Methodology Applied

Scientific EffectEvaporation: Evaporation

Data Source

PatentUS11460429B2Method for producing an ISE half-cell, ISE half-cell, sensor, and multi-parameter sensor

Publication Date: 2022.10.04 ENDRESS HAUSER CONDUCTA GMBH CO KG

AI summary

The present disclosure discloses a method for producing an ISE half-cell, including the steps of: immersing a first end of a hollow body into a membrane solution comprising at least one solvent and an ion-specific ionophore; removing the hollow body from the membrane solution; drying the hollow body and evaporating the solvent from the membrane solution, whereby an ion-selective membrane is created at the immersed end of the hollow body; and completing the hollow body to make an ISE half-cell. The present disclosure also discloses an ISE half-cell that is produced according to such a method. The present disclosure further discloses a sensor and a multiparameter sensor comprising several such ISE half-cells.