pH Sensor Reference Electrode Anti-Poisoning Design
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Solution Overview
Problem
Existing pH-sensors are prone to failure due to 'poisoning' ions that penetrate the reference electrode, causing a change in the stable reference potential and reducing the sensor's lifetime.
Innovation Solution
A reference electrode system with a porous membrane junction and non-permeable seals, combined with a sleeve to protect the silver wire, and additional rubber-based junctions to impede the path of ions, ensuring they only permeate through designated paths, thereby prolonging the sensor's lifespan.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a reference electrode is used in a pH-sensor, then the stable reference potential is generated, but poisoning ions penetrate into the reference electrode causing potential change and reducing lifetime
Solution Approach 1:
The reference electrode system is divided into multiple segments: a porous membrane junction for ion permeation, a sealed side preventing alternative ion paths, and a protected reference electrode. This segmentation isolates the reference electrode from direct ion exposure while maintaining electrical function through the membrane junction.
Solution Approach 2:
A porous membrane acts as an intermediary between the measurement medium and the reference electrode. The membrane allows controlled ion permeation for maintaining reference potential while the sealed side and protective structures prevent uncontrolled ion access that would cause poisoning.
2Stability of the object's composition
If poisoning ions are allowed to permeate through the membrane, then the reference potential is maintained, but the ions react with Ag+ causing material deposition and electrode decay
Solution Approach 1:
Different regions of the reference electrode system have different properties: the porous membrane junction allows ion permeation for potential stability, while the sealed side and protective structures create ion-impermeable zones. This local differentiation enables the reference electrode to maintain potential while protecting against poisoning reactions.
Solution Approach 2:
The sealed side and protective structures are positioned to prevent poisoning ions from reaching the reference electrode before they can cause harmful reactions. This preliminary blocking action occurs at the membrane interface, stopping ion penetration paths that would lead to Ag+ reaction, material deposition, and electrode decay.
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 solution significantly enhances the robustness and longevity of the pH-sensor system by effectively preventing ion penetration, making it more reliable and adaptable for various measurement applications.
Implementation Method 1
ions - including poisoning ions - may migrate or permeate through the membrane towards the reference electrode
Implementation Method 2
ions - including poisoning ions - may migrate or permeate through the membrane towards the reference electrode
Implementation Method 3
the sealed side may comprise or consist of any material that is hard for the ions to penetrate
Data Source
Figure 1
Figure 2~3
Figure 4
AI summary
The invention relates to the field of pH-sensors. A reference electrode system (12), a pH-sensor system (10) comprising the reference electrode system (12) and a method for manufacturing a pH-sensor system (10) are disclosed. The reference electrode system (12) comprises a first junction (50), comprising a membrane (52) with a sealed side (54), and a reference electrode (40), at least partly covered by a sleeve (44). The pH-sensor system (10) further comprises a sensor enclosure (20) and a measuring electrode (30). A sealed side (54) of a first junction (50) of the reference electrode system (12) is arranged between a membrane (52) of the first junction (50) and the sensor enclosure (20), and/or between the membrane (52) and the measuring electrode (30), thus sealing a front-side of the membrane (52) from a back-side of the membrane (52).