Tapered Flowing Liquid Junction for Electrochemical Cell Fouling
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Solution Overview
Problem
Electrochemical cells with liquid junctions are prone to fouling due to blockages, leading to increased electrical resistance and unstable readings, making them susceptible to clogging from suspended solids and chemical reactions, which complicates maintenance and reduces longevity.
Innovation Solution
A tapered flowing liquid junction design is implemented, where the diameter increases from the fill fluid aperture to the sample aperture, facilitating self-cleaning and reducing the likelihood of blockages by allowing larger particles to pass through and minimizing the risk of clogging.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a liquid junction is used to achieve stable reference potential, then the electrochemical cell gains longevity and stable readings, but the liquid junction becomes susceptible to fouling and blockages from suspended solids and chemical reactions
Solution Approach 1:
The patent changes the geometric parameter of the liquid junction by implementing a tapered configuration where the internal diameter increases from the reference electrode side to the sample side. This parameter change allows particles to more easily pass through the junction in the direction of flow, reducing fouling and blockages while maintaining stable reference potential
Solution Approach 2:
The patent applies asymmetry by creating an asymmetric tapered shape in the liquid junction where one end (sample side) has a larger diameter than the other end (reference electrode side). This asymmetric geometry prevents particles from lodging in the junction by providing a gradual expansion that facilitates particle passage while maintaining the flowing liquid junction's stability
2Loss of substance
If the passageway diameter is reduced to minimize fill solution consumption, then the liquid junction becomes more prone to blockages from particles
Solution Approach 1:
The patent changes the diameter parameter along the length of the liquid junction, creating a tapered configuration that starts with a smaller diameter at the reference electrode side (minimizing fill solution consumption) and increases to a larger diameter at the sample side (reducing blockage susceptibility). This gradient in diameter parameters optimizes both fill solution efficiency and anti-fouling performance
3Reliability
If a flowing liquid junction is implemented to maintain stable potential, then ion diffusion is overcome, but the junction becomes more vulnerable to complete blockage from severe fouling
Solution Approach 1:
The patent implements a tapered diameter parameter that increases along the flow direction, which maintains the flowing liquid junction's ability to overcome ion diffusion while reducing the risk of complete blockage. The larger exit diameter provides a clearance path for particles, extending the junction's usable life while maintaining stable electrical connection
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 tapered design enhances the stability and longevity of electrochemical cells by reducing fouling and maintaining a stable reference potential, while also lowering maintenance requirements by preventing blockages and ensuring consistent fluid flow.
Implementation Method 1
a flowing liquid junction between a reference fill fluid and a sample
Implementation Method 2
to overcome the diffusion of cations and anions in the fill solution
Data Source
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AI summary
An electrochemical cell (20) includes a measuring electrode (12) and a reference electrode (14). The reference electrode (14) includes a flowing liquid junction (22) between a reference fill fluid (24) and a sample (18). The flowing liquid junction (22) is configured to inhibit particles (30) from blocking or obstructing it. In one aspect a particle filter (32) is provided before the flowing liquid junction (22) to prevent particles (30) from the fill fluid (24) from entering the flowing liquid junction (22). In another aspect a particle filter (36) is provided after the flowing liquid junction (22) to prevent particles in the sample (18) from entering the flowing liquid junction (22). In another aspect the flowing liquid junction (22) has a diameter that generally increases from an aperture (130) proximate the fill fluid (24) to an aperture (134) proximate the sample (18). One example of such a configuration is a tapered flowing liquid junction (22).