Oxidized Carbon Nanostructure pH Sensor Eliminates Reference Electrode
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Solution Overview
Problem
Conventional pH sensors, such as glass electrodes, face challenges including temperature dependence, sensitivity to alkali-metal ions, dehydration degradation, and the need for calibration, which limits their effectiveness in extreme conditions and miniaturization, especially in applications like geochemistry and human body monitoring.
Innovation Solution
A system utilizing a substrate with a sensor medium comprising oxidized carbon nanostructures and immobilized compositions, such as conductive polymers or metal oxide nanoparticles, which function as a chemiresistor or optically measurable devices, eliminating the need for a reference electrode and providing stable, miniaturized pH sensing capabilities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If glass electrodes are used for pH sensing, then measurement capability is achieved, but device size and complexity increase due to requirement of reference electrode and salt solution-filled membrane
Solution Approach 1:
The patent extracts and eliminates the reference electrode component from the pH sensing system. By using ISFET technology with a sensitive membrane that directly responds to pH changes, the invention removes the need for a separate reference electrode and salt solution-filled membrane, thereby reducing device size and structural complexity while maintaining measurement capability
Solution Approach 2:
The patent merges the pH-sensitive detection function and the reference potential function into a single integrated ISFET device. The sensitive membrane of the ISFET combines both the measurement function and provides the necessary electrical reference, eliminating the need for separate components and enabling miniaturization
2Reliability
If glass electrodes are used for pH sensing, then measurement capability is achieved, but reliability decreases in harsh environments due to dehydration degradation and sensitivity to alkali-metal ions
Solution Approach 1:
The patent changes the material parameters of the sensing membrane from traditional glass to ISFET sensitive membrane materials that are inherently more stable. The ISFET membrane is designed to be insensitive to dehydration and alkali-metal ions while maintaining pH sensitivity, thereby improving reliability in harsh environments through material parameter optimization
Solution Approach 2:
The patent employs composite material structures in the ISFET device, combining the sensitive membrane with appropriate substrate and insulation materials that provide environmental stability. The composite structure protects the sensing element from harmful environmental factors while maintaining measurement accuracy
3Ease of operation
If glass electrodes are used for pH sensing, then measurement capability is achieved, but ease of operation decreases due to requirement for calibration with standard buffers
Solution Approach 1:
The patent implements self-service operation by designing the ISFET device with inherent stability and insensitivity to environmental variations. The device maintains consistent performance without requiring external calibration with standard buffers, as the ISFET membrane provides stable response characteristics that eliminate the need for frequent calibration operations
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 system offers robust, low-cost, and miniaturized pH sensing without the need for a reference electrode, with enhanced stability and sensitivity across a wide pH range, suitable for harsh environments and implantable applications.
Implementation Method 1
The system operates as a chemiresistor. The at least one measurement system may, for example, measure at least one electrical property of the sensor medium.
Implementation Method 2
In a number of embodiments, the at least one measurement system measures at least one optical property of the sensor medium.
Data Source
AI summary
A system for measuring pH includes a substrate and a sensor medium on the substrate. The sensor medium includes at least one oxidized carbon nanostructure and optionally at least one composition immobilized on the at least one oxidized carbon nanostructure. The at least one composition has at least one property that depends on pH. The system further includes at least one measurement system to measure a property of the sensor medium.