Ion-Selective Membrane Manufacturing via Paste Deposition
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Solution Overview
Problem
The manufacturing of ion-selective membranes for measuring cells is challenging due to the need for precise control of glass blowing methods, which are time and cost-intensive, and prone to mechanical and thermomechanical stresses that can cause cracks, limiting the production of high-quality sensors with consistent membrane thickness and shape.
Innovation Solution
A method involving a paste of ion-selective material is applied to a stick tip, heated to form a membrane on the tube end, allowing for easier control of membrane thickness and shape, reducing manufacturing complexity and stress, and enabling more efficient production of consistent membranes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If traditional glass blowing methods are used to manufacture ion-selective membranes, then membranes can be produced, but the manufacturing process is time and cost-intensive and requires highly skilled personnel
Solution Approach 1:
The patent replaces the traditional mechanical glass blowing process with a chemical deposition method. Ion-selective glass powder is suspended in a binder solution, applied to a support structure, and sintered to form membranes. This substitution eliminates the need for skilled glass blowers and manual operations, enabling automated manufacturing while maintaining membrane quality.
Solution Approach 2:
The patent changes the manufacturing parameters from high-temperature glass blowing to controlled sintering at lower temperatures (typically 600-900°C). The ion-selective material is provided as a powder or paste that can be precisely controlled in thickness and composition during application, then transformed into a solid membrane through controlled thermal processing.
2Manufacturing precision
If glass blowing methods are used to extract correct amount of glass melt, then membrane thickness can be controlled, but very accurate control of tube movement and air pressure is required
Solution Approach 1:
The patent prepares the ion-selective material in advance as a powder or paste with controlled composition and properties. The binder solution is formulated to provide optimal flow and adhesion characteristics. This preliminary preparation eliminates the need for complex real-time control of glass melt extraction and tube movement during manufacturing.
Solution Approach 2:
The patent uses a support structure (such as a porous substrate or mesh) as a template or copy for the membrane formation. The ion-selective material is deposited onto this support, which defines the final membrane shape and thickness. This approach replaces the complex control of tube movement and air pressure with a simpler deposition process on a predefined substrate.
3Reliability
If cooling process is applied to solidify the membrane, then the membrane is formed, but cracks and thermomechanical tensions may occur due to different coefficients of thermal expansion
Solution Approach 1:
The patent changes the thermal processing parameters by using lower sintering temperatures and controlled cooling rates. The binder solution is formulated to evaporate completely during sintering, leaving only the ion-selective glass matrix. This controlled thermal regime minimizes thermal gradients and expansion differences, preventing cracks and internal stresses.
Solution Approach 2:
The patent uses a composite material system consisting of ion-selective glass powder mixed with a binder solution. The binder acts as a matrix that holds the glass particles together during processing and then disappears (evaporates) during sintering, leaving a porous or dense glass structure depending on the process parameters. This composite approach allows controlled shrinkage and stress relief during the phase transition.
4Measurement precision
If membranes are made thinner to reduce electrical impedance, then measurement accuracy is improved, but manufacturing precision requirements increase
Solution Approach 1:
The patent enables different regions of the membrane to have different thicknesses or properties if needed. The ion-selective material can be applied with varying concentrations or layers of different compositions to optimize both thinness for low impedance and structural integrity. The support structure allows precise control of local membrane thickness during deposition.
Solution Approach 2:
The support structure serves as a template that defines the membrane thickness uniformly across the surface. By controlling the deposition amount and support pore structure, very thin and uniform membranes can be manufactured with high precision, eliminating the need for complex manual thinning processes.
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 manufacturing process, reduces costs, and minimizes mechanical and thermomechanical stresses, enabling the production of high-quality ion-selective membranes with consistent thickness and shape, improving sensor accuracy and sensitivity.
Implementation Method 1
heating the first end of the tube and heating the dispensed paste to a temperature causing the dispensed paste to melt and a thus-produced melt to form a film
Implementation Method 2
transforming the film into the membrane joined to the tube by cooling the first end of the tube and the film to a temperature below a melting point of the ion-selective material
Data Source
AI summary
A method of and an apparatus for manufacturing a measuring cell comprising a tube having a first end capped by a membrane of an ion-selective material, comprising the steps of: providing a paste comprising all constituents of the ion-selective material; mounting the tube onto a stick with a tip such that the stick extends through the tube; dispensing an amount of the paste onto the tip; heating the first end of the tube and the dispensed paste to a temperature causing the dispensed paste to melt and the thus-produced melt to form a film covering the tip and an end surface of the first end of the tube; transforming the film into the membrane joined to the tube by cooling the first end of the tube and the film to a temperature below a melting point of the ion-selective material; and separating the thus-manufactured measuring cell from the stick.