Single-Rod Measuring Chain with Hydrogel Diaphragm to Reduce KCl Outflow
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Solution Overview
Problem
Conventional combination electrodes suffer from contamination and KCl outflow through porous diaphragms, leading to measurement errors and a limited service life, which is exacerbated by sulfide precipitation in the diaphragm, making them unsuitable for applications requiring high accuracy and compliance with Good Manufacturing Practice (GMP) guidelines.
Innovation Solution
The use of a hydrogel diaphragm, preferably made of thermoplastic polyurethane or smart hydrogel, which minimizes KCl outflow and contamination, ensuring long-term error-free measurements by sealing the electrode and accommodating temperature fluctuations, while being compatible with GMP standards.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a porous diaphragm is used to allow charge transfer, then charge transport between the KCl solution and the measuring fluid is enabled, but the diaphragm's porous structure results in a large surface area that is prone to progressive contamination over time
Solution Approach 1:
The patent replaces the traditional porous diaphragm with a non-porous hydrogel diaphragm. The hydrogel achieves charge transfer through ion exchange mechanisms rather than physical pores, eliminating the porous structure that causes contamination. This resolves the contradiction by maintaining charge transport capability while removing the harmful porous surface area that accumulates contamination.
Solution Approach 2:
The patent uses a composite structure combining hydrogel material with the diaphragm function. The hydrogel comprises multiple functional components that work together to provide both charge transfer and contamination resistance. This composite approach allows the diaphragm to achieve multiple functions simultaneously, resolving the contradiction between charge transport and contamination prevention.
2Reliability
If a porous diaphragm is used to enable charge transfer, then charge transport is allowed, but KCl can flow out of the combination electrode via the diaphragm, causing KCl blooming and change in KCl concentration
Solution Approach 1:
The patent eliminates the porous structure that enables KCl leakage. The non-porous hydrogel diaphragm uses ion exchange mechanisms rather than physical pores for charge transfer, thereby preventing KCl from flowing out through the diaphragm while still maintaining electrical conductivity for charge transport.
Solution Approach 2:
The patent changes the physical and chemical parameters of the diaphragm material from porous to non-porous hydrogel. This parameter change fundamentally alters how charge transfer occurs (from physical pore transport to ion exchange), thereby preventing KCl outflow while maintaining charge transport capability.
3Reliability
If a porous diaphragm is used, then charge transfer is enabled, but the diaphragm is susceptible to sulfide precipitation which clogs the pores and impedes charge transport
Solution Approach 1:
The patent replaces the porous diaphragm with a non-porous hydrogel, eliminating the pore structure that sulfide precipitation clogs. The hydrogel's non-porous nature prevents sulfide accumulation while maintaining charge transfer through ion exchange mechanisms, resolving the contradiction between charge transport and sulfide precipitation susceptibility.
4Reliability
If the combination electrode is stored in a liquid to prevent diaphragm drying, then diaphragm moisture is maintained, but this is an additional requirement that complicates storage and handling
Solution Approach 1:
The hydrogel diaphragm is hydrophilic and automatically absorbs and retains moisture from the surrounding environment, including from the KCl solution itself. This self-moistening capability eliminates the need for external liquid storage requirements, as the diaphragm maintains its own moisture levels through its hydrophilic properties.
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 hydrogel diaphragm significantly reduces KCl outflow and contamination, extending the service life of the combination electrode, maintaining measurement accuracy, and allowing sterilization without functional loss, making it suitable for use in fermenters and disposable systems.
Implementation Method 1
The diaphragm is characterized by the fact that it prevents mixing of the KCl solution and the measuring fluid, but allows charge transfer between the KCl solution and the measuring fluid
Implementation Method 2
bringing the hydrogel into contact with the first electrically conductive fluid, causing the hydrogel to swell and seal the opening
Implementation Method 3
the hydrogel is elastic, allowing it to compensate for temperature fluctuations, thus keeping the combination electrode sealed
Implementation Method 4
the outflow of the first electrically conductive fluid via the diaphragm in the combination electrode according to the invention is much lower than in a conventional combination electrode having a porous diaphragm
Data Source
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AI summary
The invention relates to a single-rod measuring chain (1) for measuring a measuring fluid, comprising a working electrode (2), a reference electrode (3), a diaphragm (10), and a first electrically conductive fluid (6) which is in contact with the reference electrode (3) and the diaphragm (10), such that the diaphragm (10) is electrically connected to the reference electrode (2) via the first electrically conductive fluid (6), wherein the diaphragm (10) comprises a hydrogel. The invention also relates to a method for manufacturing the single-rod measuring chain (1).