Substrate Recess for Silver Contamination Control
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Solution Overview
Problem
In printed electrochemical cells, silver contamination from tracks to working electrodes degrades performance and accuracy due to oxidation reactions and instability, and the use of silver depleted recesses on the same face as the working electrode causes sealing issues and reduces the electrochemical signal.
Innovation Solution
The solution involves printing the working electrode on one face of the substrate and the silver track on the opposite face, with a recess extending through the substrate to maintain electrical contact while minimizing silver particle migration, using a binary mixture of carbon and silver inks to create a conductive path with controlled silver concentration, and employing truncated cone shapes to optimize the contact block and track configurations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If silver particles are used in conductive tracks to reduce electrical resistance, then electrical conductivity is improved, but silver particles migrate to the working electrode surface causing contamination and measurement degradation
Solution Approach 1:
The conductive path is segmented into three distinct zones with different silver concentrations: a high-silver track for conductivity, a low-silver buffer zone to prevent migration, and a silver-free working electrode surface for accurate measurements. This segmentation resolves the contradiction by spatially separating the conductivity function from the measurement function.
Solution Approach 2:
Different regions of the conductive structure are assigned different material compositions: the track region has high silver content for conductivity, the buffer zone has reduced silver content to prevent contamination, and the electrode surface has no silver to ensure measurement accuracy. This local quality variation allows each region to optimize its specific function.
2Object-generated harmful factors
If silver depleted recesses are placed on the same face as the working electrode to prevent contamination, then silver migration is reduced, but sealing issues occur and the electrochemical signal is reduced
Solution Approach 1:
The silver buffer zone is extended into the third dimension by forming a recess that penetrates through the substrate thickness. This vertical extension creates a gradient structure that prevents silver migration while maintaining a flat sealing surface on the outer face, resolving both the contamination and sealing contradictions.
Solution Approach 2:
The recess structure nests the low-silver buffer zone within the substrate thickness, creating a hierarchical structure where the buffer zone is contained within the substrate volume. This nesting allows the buffer to prevent contamination without interfering with the external sealing surface.
3Measurement precision
If the working electrode surface area is maximized to increase electrochemical signal, then measurement sensitivity is improved, but silver contamination from tracks increases
Solution Approach 1:
A silver-depleted buffer zone acts as an intermediary structure between the high-silver conductive track and the working electrode surface. This intermediary prevents direct contact and migration of silver particles while allowing electrical connection, thus protecting the electrode surface from contamination.
Solution Approach 2:
Silver particles are extracted or removed from the buffer zone adjacent to the working electrode surface, creating a low-silver or silver-free region. This extraction eliminates the contamination source while maintaining the conductive path through the high-silver track region.
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 configuration reduces silver contamination, enhances the electrochemical signal quality, and improves the long-term sealing of the cell by isolating non-metrological elements from the measurement surface, thereby increasing the accuracy and stability of the electrochemical measurements.
Implementation Method 1
a percolation appears between the particles in solution in the polymer and an electrical conduction is observed based on the concentration of particles of carbon and silver
Implementation Method 2
The solvent evaporates once the ink is printed on a surface
Implementation Method 3
the presence of solvent during the deposit by printing causes an exchange of silver particles at the junction of a carbon electrode and a track by producing a gradation in silver concentration. Likewise, the polymers of the inks are affected by creeping causing migration of silver particles to the surface of a working electrode
Data Source
AI summary
Device comprising a substrate (1), an electrode (2), a track (4) and a recess (3), wherein the substrate extends over a first thickness, between a first face and a second face, wherein the electrode is printed on the first face, wherein the track is printed on the second face, wherein the substrate is electrically insulated, wherein the electrode is conductive to electricity essentially through carbon particles, wherein the track is conductive to electricity and contains particles of silver, wherein the recess is conductive to electricity and is made of an ink which comprises a binary mixture of carbon and silver in proportions where the quantity of silver divided by the sum of the quantities of carbon and silver present in the binary mixture is comprised within a 0 to 1 interval, wherein the recess extends within the substrate from the first face to the second face, wherein the recess is in electrical contact with the electrode at the level of a first junction located on the first face, wherein the recess is in electrical contact with the track at the level of a second junction located on the second face, and wherein the linear density of silver particles in the recess at the level of the first junction, perpendicularly to the current lines when a current passes through the first junction, is lower than the linear density of silver particles in the track at the level of the second junction, perpendicularly to the current lines when a current passes through the second junction. By using such binary mixture of carbon and silver in the recess (3), silver contamination in electrochemical cells using silver tracks is reduced.