Planar CO2 Sensor Electrolyte Osmotic Stability
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Solution Overview
Problem
Planar CO2 sensors face issues with osmotic imbalances leading to swelling or shrinking of the electrolyte layer, causing mechanical stress and potential delamination, and existing solutions either compromise sensitivity or result in prolonged response times due to inappropriate electrolyte concentrations.
Innovation Solution
A planar CO2-sensing device with an electrolyte layer containing osmotically active species in the range of 0.8-6.0 milliosmol per m2, incorporating a hydrophilic osmolarity increasing component that does not add bicarbonate or chloride ions, ensuring controlled electrolyte dimensional boundaries and suitable response times.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If the concentration of osmotically active species in the electrolyte layer is increased to match blood osmolarity (320 mOsM), then water migration and swelling/shrinking are reduced, but sensor sensitivity is compromised
Solution Approach 1:
The patent changes the chemical composition parameters of the electrolyte layer by introducing non-ionic osmotic agents (sucrose, glucose, polyethylene glycol) alongside ionic species. This allows independent optimization of osmolarity (to match blood) and ionic concentration (for sensitivity), resolving the contradiction between stability and precision
Solution Approach 2:
The electrolyte layer is formulated as a composite system containing both ionic species (for electrochemical function and sensitivity) and non-ionic osmotic agents (for volume stability). This composite approach allows simultaneous achievement of both stability and sensitivity requirements
2Measurement precision
If the concentration of osmotically active species in the electrolyte layer is decreased, then sensor sensitivity is maintained, but water migration causes swelling or shrinking leading to mechanical stress and delamination
Solution Approach 1:
The patent modifies the osmotic parameter profile by adding non-ionic osmotic agents, enabling the electrolyte to maintain low ionic concentration (for sensitivity) while achieving high total osmolarity (for structural stability through osmotic equilibrium with blood)
Solution Approach 2:
The electrolyte layer combines ionic species (at low concentrations for sensitivity) with non-ionic osmotic agents (at high concentrations for structural stability), creating a composite system that simultaneously achieves both sensitivity and reliability
3Stability of the object's composition
If the electrolyte layer thickness is increased to prevent dehydration, then structural stability is improved, but sensor response time increases
Solution Approach 1:
The patent changes the osmotic parameter of the electrolyte layer by adding non-ionic agents, enabling maintenance of thin layer geometry (for fast response) while achieving osmotic equilibrium with blood (for stability), thus resolving the time-stability contradiction
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 approach reduces the risk of delamination and maintains optimal response times, achieving stable sensor performance without compromising sensitivity, even when exposed to blood samples or similar solutions.
Implementation Method 1
an osmotic equilibrium will be established across the outer membrane whenever contacted with a blood sample. Dependent on the concentrations of osmotically active species on either side of the membrane, water may migrate across the membrane
Implementation Method 2
CO2 from the sample diffuses across an outer membrane into an electrolyte layer, the pH of which is in turn determined
Implementation Method 3
the outer membrane should allow CO2 to penetrate, but should keep ionic species from entering the electrolyte compartment
Data Source
AI summary
A CO2-sensitive planar sensing device is disclosed, which has an electrode with an ion-selective layer, an electrolyte layer and an outer layer. The electrolyte layer has osmotically active species in an amount of 0.8-6.0 milliosmol per m2 of electrolyte layer area, and has a hydrophilic osmolarity increasing component which does not add bicarbonate ions or chloride ions to the electrolyte layer.