Disposable Oxygen Sensor Membrane for Stable Diffusion Control
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Solution Overview
Problem
Existing single-use electrochemical oxygen sensors face challenges in achieving accurate and precise measurements due to the use of large electrodes that generate high current, leading to sample depletion and erratic values, and manufacturing processes are complex and costly.
Innovation Solution
A multi-layer reagent matrix is formed over a working electrode, comprising a hydrophilic polymer layer and a hydrophobic polymer layer, where the hydrophilic layer includes a diffusion-limiting layer with an epoxy network and a hydrophobic cover membrane that allows for controlled oxygen diffusion, preventing path length changes upon hydration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a large electrode surface is used in a single-use oxygen sensor, then the manufacturing cost is reduced and ease of manufacture is improved, but the generated current becomes too large causing sample depletion and measurement inaccuracy
Solution Approach 1:
The patent applies local quality by creating a diffusion limiting layer with specific properties (thickness of 1-10 micrometers, controlled oxygen permeability) that is applied locally over the electrode surface. This layer has different characteristics from the rest of the sensor structure, specifically designed to limit oxygen diffusion and reduce the effective current while maintaining the benefit of a large electrode area for manufacturing simplicity.
Solution Approach 2:
The patent uses composite materials by combining the electrode substrate with a diffusion limiting layer made from specific polymer materials (such as polyvinyl alcohol, carboxymethyl cellulose, or gelatin) mixed with oxygen impermeable particles (such as silver chloride, barium sulfate, or titanium dioxide). This composite structure allows the sensor to maintain large electrode area while controlling oxygen diffusion to achieve accurate measurements.
2Measurement precision
If a diffusion limiting layer is added to control oxygen diffusion, then measurement precision is improved, but the device complexity and manufacturing process become more complex
Solution Approach 1:
The patent applies parameter changes by carefully controlling the thickness of the diffusion limiting layer (1-10 micrometers) and the composition ratios of the polymer matrix and oxygen impermeable particles. By adjusting these parameters, the oxygen diffusion rate is precisely controlled to match the consumption rate at the electrode, achieving accurate measurements without requiring complex multi-layer structures or additional components.
Solution Approach 2:
The patent implements preliminary action by pre-mixing the polymer material with oxygen impermeable particles to create a homogeneous diffusion limiting composition before applying it to the electrode. This pre-prepared mixture ensures uniform oxygen diffusion characteristics across the electrode surface, simplifying the manufacturing process and reducing device complexity while maintaining measurement precision.
3Measurement precision
If the diffusion limiting layer path length is increased to reduce current, then measurement accuracy improves, but the layer becomes more prone to hydration and path length changes
Solution Approach 1:
The patent applies parameter changes by optimizing the diffusion limiting layer thickness to a specific range (1-10 micrometers) that balances two competing requirements: thick enough to limit oxygen diffusion and improve measurement accuracy, but thin enough to minimize hydration effects and maintain path length stability. This optimal thickness parameter resolves the contradiction between accuracy and stability.
Solution Approach 2:
The patent uses composite materials by combining hydrophilic polymer matrices (which provide good oxygen solubility and diffusion) with oxygen impermeable particles (such as silver chloride, barium sulfate, or titanium dioxide). This composite structure creates a diffusion limiting layer that maintains stable path length while providing controlled oxygen diffusion, as the impermeable particles prevent excessive water uptake and structural changes during hydration.
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 enables accurate and precise measurement of dissolved oxygen in a small fluid sample with high accuracy and precision, while being cost-effective and disposable, overcoming the limitations of conventional sensors.
Implementation Method 1
formulated a diffusion layer that limits oxygen diffusion from the sample to the electrode
Implementation Method 2
The hydrophilic layer includes a diffusion-limiting layer with an epoxy network
Implementation Method 3
a hydrophobic membrane formed from a hydrophobic solution disposed over the hydrophilic layer, the hydrophobic solution containing an acetate copolymer and a cross-linking agent
Data Source
Figure 1
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Figure 3~4
AI summary
An electrochemical oxygen sensor includes a sensing surface having a working electrode and a reference electrode, a hydrophilic layer formed from an oxygen diffusion-limiting layer emulsion overlaying the working electrode and a hydrophobic membrane formed from a hydrophobic solution disposed over the hydrophilic layer. The hydrophilic layer contains an epoxy network and a hydrophilic polymer. The hydrophobic layer contains an acetate copolymer and a cross-linking agent that reacts with the liquid epoxy resin in the hydrophilic layer forming the epoxy network where the hydrophobic member is water vapor and oxygen permeable.