AgCl-Coated Silver Ink Composition for Hydrogel-Stable Electrodes
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Solution Overview
Problem
Existing electrically conductive printable inks with high AgCl content suffer from instability when in contact with hydrogels due to oxidation, and those with low AgCl content degrade quickly, while high-temperature curing thermosetting inks limit substrate choice and increase energy consumption.
Innovation Solution
An electrically conductive ink composition comprising AgCl coated silver particles, a resin, and a solvent, which provides high AgCl availability and stability with hydrogels, using thermoplastic polyurethanes for flexibility and compatibility, and suitable solvents for printing, allowing low-temperature curing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If high AgCl quantity (30-40%) is used in printable ink, then sufficient AgCl is provided for Ag/AgCl redox reaction, but the ink loses stability towards hydrogels due to oxidation of silver particles
Solution Approach 1:
The patent uses a composite particle structure where silver core particles are coated with silver chloride shell. This composite AgCl-coated Ag particle combines the electrical conductivity of silver with the redox activity of AgCl, providing both high AgCl availability and improved stability against oxidation when in contact with hydrogels.
Solution Approach 2:
The patent changes the particle morphology from conventional mixtures of separate Ag and AgCl particles to coated particles with specific size ratios (core to shell). This parameter change in particle structure optimizes both the electrical conductivity and the chemical stability while maintaining high AgCl content.
2Reliability
If low AgCl quantity (10-20%) is used in printable ink, then stability towards hydrogels is improved, but the electrical conductivity of the Ag/AgCl layer degrades quickly
Solution Approach 1:
The coated particle structure ensures that AgCl is distributed throughout the particle volume rather than just on the surface, providing sustained redox activity over time while maintaining stability. The silver core provides continuous electrical conductivity pathway.
3Reliability
If thermosetting (epoxy-based) resin inks are used, then chemical resistance and stability with hydrogel are improved, but high curing temperatures (>120°C) are required limiting substrate choice and increasing energy consumption
Solution Approach 1:
The patent changes the resin system from thermosetting epoxy-based to thermoplastic polyurethane-based, which eliminates the need for high-temperature curing. The thermoplastic system provides sufficient chemical resistance and adhesion at lower temperatures, enabling use with temperature-sensitive substrates and reducing energy consumption.
Solution Approach 2:
The patent employs disposable, single-use electrodes with the conductive ink layer that are discarded after use, eliminating the need for complex, reusable electrode structures and reducing overall energy consumption and manufacturing complexity.
4Reliability
If thermosetting inks are used, then chemical resistance is improved, but shelf life is limited and storage below room temperature is required
Solution Approach 1:
The patent changes the resin chemistry from thermosetting to thermoplastic, which fundamentally improves shelf stability. The thermoplastic polyurethane system does not require curing, eliminating the shelf-life limitations associated with thermosetting inks that contain reactive monomers and catalysts.
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 composition achieves better biosignal quality, faster voltage discharge, and improved stability with hydrogels, maintaining conductivity and flexibility without high-temperature curing, suitable for biosignal sensing electrodes.
Implementation Method 1
They provide sufficient AgCl quantity for the Ag/AgCl redox reaction
Implementation Method 2
The electrically conductive printable inks function in medical electrodes as reference/counter electrodes
Data Source
AI summary
The present invention relates to an electrically conductive ink composition comprising a) a resin; b) a solvent; and c) AgCl coated silver particles. The conductive ink composition according to the present invention provides good adhesion to polymer substrates, a good electrical conductivity, as well as a good compatibility and stability with high salt content hydrogels. The electrically conductive ink composition according to the present invention is suitable for use in medical applications such as hydrogel containing biosignal sensing electrodes and as reference/counter electrodes for electrochemical sensors.