Hydrogel-Based pH Sensors Using Capacitance for In-Situ Monitoring
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Solution Overview
Problem
Conventional pH monitoring methods, such as insertion probes and laboratory analysis, are invasive, costly, and unsuitable for continuous monitoring in applications like oil and gas pipelines, leading to delays in obtaining useful pH data.
Innovation Solution
A hydrogel-based sensor comprising a first and second electrode layer with a magnetorheological elastomer, a dielectric layer of non-conductive elastomer, and a pH-sensitive hydrogel sensing layer on the outer surface of the second electrode layer, which measures capacitance changes to determine pH levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional insertion probes or laboratory analysis are used for pH monitoring, then measurement capability is provided, but the methods are invasive, require expensive and bulky instrumentation, and cause delays between sampling and analysis
Solution Approach 1:
The patent replaces conventional mechanical insertion probes with a flexible sensor that uses capacitance measurement principles. The sensor employs a dielectric layer and electrode structure where pH-induced hydrogel swelling changes capacitance, eliminating the need for invasive mechanical probes while enabling continuous real-time monitoring without sampling delays
Solution Approach 2:
The patent utilizes pH-induced changes in hydrogel swelling to alter capacitance parameters. The pH-sensitive hydrogel changes its physical state in response to pH variations, which directly modifies the capacitance between electrode layers, providing a direct and immediate measurement of pH without time delays
2Measurement precision
If conventional insertion probes are used, then pH measurement is possible, but the instrumentation is expensive and bulky
Solution Approach 1:
The patent employs flexible thin film structures for both the dielectric layer and the pH-sensitive hydrogel. This flexible film approach replaces bulky rigid instrumentation with a lightweight, flexible sensor that can be easily integrated into various environments, reducing both the size and cost of the measurement system while maintaining measurement capability
Solution Approach 2:
The patent creates a simplified model system that copies the essential measurement function of expensive conventional probes. By using a simplified electrode-capacitance-hydrogel structure, the patent achieves pH measurement capability without requiring the complex and expensive instrumentation traditionally used, making the system more affordable and compact
3Measurement precision
If conventional sampling methods are used, then pH analysis can be performed, but the methods are invasive and require point-specific sampling
Solution Approach 1:
The patent replaces invasive mechanical sampling with a non-invasive capacitance measurement system. The sensor measures pH directly through electrical field interactions with the hydrogel, eliminating the need for physical insertion and point-specific sampling, thereby reducing invasiveness and enabling continuous monitoring
Solution Approach 2:
The patent enables continuous pH monitoring through real-time capacitance measurement. Unlike conventional methods that require discrete sampling events, the sensor continuously measures pH changes as they occur, providing ongoing data without requiring repeated invasive sampling 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 sensor provides continuous, in-situ pH monitoring, offering flexible and non-invasive measurements that can be used to map local pH levels across arrays, improving the efficiency and accuracy of pH analysis in various applications.
Implementation Method 1
Because pH-responsive changes in the volume of the hydrogel can affect the distance between the first and second electrode layers
Implementation Method 2
The first electrode layer and the second electrode layer each independently include a magnetorheological elastomer
Implementation Method 3
measuring a capacitance between the first electrode layer and the second electrode layer
Data Source
AI summary
The present disclosure relates to sensors including a dielectric layer disposed between a first electrode layer and a second electrode layer, and a sensing layer including a pH-sensitive hydrogel disposed on an outer surface of the second electrode layer.