Oxygen Sensor Microporous Electrolyte Silver Ion Migration
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Solution Overview
Problem
Existing electrochemical sensors for point-of-care oxygen measurement face challenges in achieving long shelf life, long in-use service life, and rapid activation due to issues with electrolyte layer compatibility, silver ion interference, and high production costs, leading to limited service life and reliability.
Innovation Solution
An electrochemical sensor design featuring a porous, non-swellable electrolyte layer formed from particulate material and binder, with zeolites as preferred particulate material, and a gas-permeable cover layer with recesses to reduce silver ion migration and enhance electrolyte absorption, allowing for extended service life and quicker activation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of stationary object
If a microporous inner electrolyte layer is used, then the sensor can achieve long-term storability and in-use life, but silver ions can still migrate to the working electrode and contaminate it, limiting service life
Solution Approach 1:
A gel layer is introduced as an intermediary between the microporous inner electrolyte layer and the working electrode. This gel layer acts as a barrier that prevents silver ions from migrating to the working electrode while still allowing oxygen to reach the electrode surface. The gel layer is formed by applying a gel-forming solution containing crosslinking agents to the inner electrolyte layer, which then cures to create this protective intermediate barrier.
Solution Approach 2:
The sensor employs a composite structure combining multiple materials with different functions: a microporous inner electrolyte layer for ion conduction and oxygen transport, a gel layer for silver ion blocking, and a gas-permeable cover membrane for oxygen diffusion. This multi-material composite approach allows each layer to address specific problems, achieving both long service life and protection against contamination.
2Duration of action of stationary object
If the sensor is designed for repeated measurements with long service life, then sensor changes occur less frequently, but the activation time after sensor change must be minimized
Solution Approach 1:
The gel layer is pre-formed and integrated into the sensor structure before the sensor is put into use. This preliminary action ensures that the protective barrier against silver ion migration is already in place, allowing the sensor to be activated quickly after insertion without requiring additional preparation time for forming protective layers.
Solution Approach 2:
The gel layer's physical and chemical parameters are optimized to allow rapid oxygen diffusion while providing effective silver ion blocking. By adjusting the gel's porosity, crosslinking density, and composition, the sensor achieves both fast activation and long-term protection, reducing the trade-off between service life and activation time.
3Reliability
If a gas-permeable cover membrane is used to separate sample from internal electrolyte, then ion and liquid impermeability is achieved, but activation time is extended due to slow electrolyte formation
Solution Approach 1:
The cover structure is segmented into a gas-permeable cover membrane and a separate gel layer. The gas-permeable membrane maintains its function of separating the sample from the internal electrolyte while allowing oxygen diffusion, while the gel layer provides a controlled interface that facilitates faster electrolyte formation and activation without compromising the separation effectiveness.
4Duration of action of stationary object
If electrodes are stored dry and electrolyte is formed in situ, then long-term storability is achieved, but the sensor requires water diffusion and electrolyte formation time before use
Solution Approach 1:
The gel layer is pre-formed during sensor manufacturing, creating a structure that facilitates rapid water diffusion and electrolyte formation when the sensor is activated. This preliminary preparation of the gel matrix reduces the time required for water to diffuse through and form the liquid electrolyte, while the sensor can still be stored dry for long-term shelf life.
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 sensor achieves a longer service life of over four weeks with reduced silver ion interference and faster activation, improving reliability and cost-effectiveness by using zeolites and a gas-permeable cover layer with recesses to manage electrolyte absorption and ion migration.
Implementation Method 1
an electrolyte layer which is formed from at least one particulate material and at least one binder and has a porous, non-swellable framework structure
Implementation Method 2
a gas-permeable cover layer arranged over the electrolyte layer
Implementation Method 3
with zeolites as preferred particulate material, and a gas-permeable cover layer with recesses to reduce silver ion migration
Data Source
Figure 1A
Figure 1B
Figure 2A~2B
AI summary
The electrochemical sensor has a gas-permeable cover layer (7) provided with a recess (12) that allows the contact of a portion of an electrolyte layer (6) with a sample aqueous medium. The electrolyte layer is arranged between a working electrode (3) and a counter electrode (5), where the electrolyte layer is comprised of a particulate material and a binder. Independent claims are also included for the following: (1) a method for manufacturing electrochemical sensor; and (2) a method for determining dissolved oxygen in aqueous medium.