Planar Ion Sensor with Solid-State Reference Electrode
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Solution Overview
Problem
Current ion sensors require bulky reference electrodes that need conditioning and a large sample volume, making them unsuitable for disposable or portable applications, and they require calibration with known ion solutions, which is time-consuming.
Innovation Solution
A compact, planar ion sensor design featuring a non-conductive substrate with ion-selective electrodes and a solid-state reference electrode made of silver-silver chloride, combined with a polymer and chloride-containing salt, which eliminates the need for conditioning and reduces sample volume requirements, and includes a microfluidic layer and filter material for efficient ion detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a traditional reference electrode with hydrogel and screen-printed Ag/AgCl electrode is used, then the electrode potential can be stable, but the electrode becomes bulky and requires a large volume of sample solution
Solution Approach 1:
The patent uses a thin film reference electrode design where the reference electrode is formed as a planar structure on a substrate. The reference electrode layer is deposited as a thin film rather than using a bulky three-electrode system, enabling the electrode to function with minimal sample volume while maintaining stable potential through the thin film configuration
Solution Approach 2:
The patent creates a planar copy of the traditional reference electrode functionality on a two-dimensional substrate. Instead of using a volumetric three-electrode system, the reference electrode is replicated as a thin film layer with Ag/AgCl material deposited on a planar substrate, achieving the same electrochemical function in a minimized volume
2Volume of moving object
If a planar reference electrode with hydrogel is used, then the electrode size is reduced, but the electrode requires conditioning for several hours before use
Solution Approach 1:
The reference electrode is pre-formed during manufacturing with the Ag/AgCl material already deposited and configured on the substrate. The electrode is prepared in advance during the fabrication process, eliminating the need for post-manufacturing conditioning steps. The thin film structure is created with proper composition and morphology before use, so no additional conditioning time is required
Solution Approach 2:
The patent describes a disposable ion sensor where the reference electrode is manufactured as a single-use component. The electrode is pre-prepared in a disposable format that eliminates the need for conditioning, cleaning, or maintenance between uses. Each sensor is ready to use immediately upon opening, with the reference electrode already in its operational state
3Reliability
If a traditional reference electrode is used, then the electrode can provide stable potential, but the electrode structure becomes complex and difficult to integrate with ion-selective electrodes
Solution Approach 1:
The patent combines the reference electrode and ion-selective electrode into a single integrated planar sensor on one substrate. Both electrodes are formed on the same substrate using compatible deposition techniques, with insulating layers separating their active areas. This merging eliminates the need for separate electrode assemblies and simplifies the overall device structure while maintaining stable reference potential
Solution Approach 2:
The patent transitions from a three-dimensional bulky reference electrode structure to a two-dimensional planar configuration. The reference electrode is deposited as a thin film layer on the substrate surface, reducing the vertical dimension and enabling easy integration with ion-selective electrodes in the same planar space. This dimensional change simplifies the overall device architecture
4Ease of operation
If ion sensors are made disposable, then the sensors become more accessible and easier to use, but the reference electrode requires conditioning that is not practical for disposable sensors
Solution Approach 1:
The reference electrode is pre-conditioned during the manufacturing process, with the Ag/AgCl material deposited and the thin film structure formed in the correct operational state before the sensor leaves the factory. This preliminary preparation eliminates the need for user conditioning steps, making the disposable sensor ready to use immediately upon opening
Solution Approach 2:
The patent describes a disposable ion sensor where the reference electrode is designed as a single-use component that requires no conditioning. The electrode is manufactured in a ready-to-use state and discarded after one use, eliminating the impracticality of conditioning steps. The disposable nature of the sensor allows the reference electrode to be pre-prepared in a format that eliminates maintenance requirements
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 improved ion sensor is disposable, requires only a small sample volume, provides long-term stability, and does not need calibration before use, making it suitable for portable and disposable applications while maintaining accurate ion detection capabilities.
Implementation Method 1
Ion sensors typically work by generating voltages that scale with the concentration of an ion in the solution being tested
Implementation Method 2
A commonly used type of reference electrode is made up of a silver chloride electrode (Ag/AgCl) material immersed in a 3 molar potassium chloride (KCl) solution
Data Source
AI summary
An ion sensor includes a substrate, at least one ion selective electrode deposited on the substrate, and a reference electrode deposited on the substrate. The sensor may further include an insulating layer placed over the ion selective electrode and the reference electrode and having openings for the ion selective electrode and the reference electrode, a microfluidic layer placed over at least part of the insulating layer, and a cover layer placed over the microfluidic layer. The reference electrode includes reference electrode material deposited on the substrate and a combination of a polymer and a chloride-containing salt deposited on the reference electrode material.