Phenolic pH Sensor with Sulphur Hydrogen Bonding
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Solution Overview
Problem
Existing pH sensors, particularly those using quinone and phenol-based systems, face instability and low accuracy in low buffer/low ionic strength analytes like water and seawater, due to solubility issues and poor polymerization, making them unsuitable for prolonged use and precise measurements.
Innovation Solution
An electrochemical pH sensor utilizing a phenolic compound with a sulphurous atom attached to its aromatic ring, forming hydrogen bonds, which stabilizes and forms a polymer on the electrode, enabling long-term accurate pH measurement in low buffer/low ionic strength solutions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If quinone and phenol-based systems are used for pH sensing in low buffer/low ionic strength analytes, then the sensor can operate in challenging media like water and seawater, but the sensor exhibits instability and low accuracy due to solubility issues and poor polymerization
Solution Approach 1:
The patent applies composite materials by combining phenolic compounds with specific substituents (sulphurous atoms, hydrogen bond donors/acceptors) to create a polymerizable redox-active species. This composite structure enables both solubility control and stable polymerization on the electrode surface, resolving the contradiction between adaptability to low ionic strength media and measurement reliability. The composite nature allows the material to function as both a redox indicator and a stable polymer matrix.
Solution Approach 2:
The patent utilizes parameter changes by modifying the chemical structure of phenolic compounds through specific substitutions (introducing sulphurous atoms at defined positions, adding hydrogen bond donors/acceptors). These structural parameter changes enable control over polymerization behavior and solubility characteristics, allowing the sensor to maintain stability and accuracy across different ionic strength conditions while retaining adaptability to challenging media.
2Duration of action of stationary object
If phenolic compounds are used to form polymers on the electrode, then prolonged use is enabled, but poor polymerization occurs leading to low measurement accuracy
Solution Approach 1:
The patent applies local quality by positioning specific functional groups (sulphurous atoms, hydrogen bond donors/acceptors) at defined locations within the phenolic compound structure. This localized functional arrangement promotes uniform and controlled polymerization at the electrode surface, ensuring both prolonged operational duration and high measurement precision. The local structural quality control prevents poor polymerization while enabling long-term stability.
3Measurement precision
If glass electrodes are used for pH measurement, then accurate pH readings are obtained, but the electrodes are fragile and require calibration and specific storage conditions
Solution Approach 1:
The patent applies the disposable principle by developing a polymer-based electrochemical sensor that can be manufactured as a single-use or limited-use device. The polymerizable phenolic compound forms a stable coating on the electrode that provides sufficient operational life for practical applications without requiring recalibration or special storage conditions. This approach trades long-term reusability for operational simplicity and robustness.
Solution Approach 2:
The patent applies self-service through the self-assembling and self-polymorizing properties of the phenolic compound on the electrode surface. The compound automatically forms a stable polymer coating without requiring external intervention for calibration or maintenance. The sensor essentially calibrates and prepares itself through the spontaneous polymerization process, eliminating the need for user calibration and special storage procedures.
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 sulphur-hydrogen bonding in the phenolic compound creates a stable polymer that facilitates proton transfer, providing precise and stable pH measurements over a wide range (3 to 12) without electrode passivation, enhancing the sensor's durability and accuracy in challenging media like seawater and saline solutions.
Implementation Method 1
the phenolic compound includes a sulphurous atom attached either directly or indirectly to the aromatic ring of the phenolic compound and configured to form a hydrogen bond with the hydrogen atom associated with the hydroxyl moiety of the phenolic compound
Implementation Method 2
U.S. Patent Publication No. 2014/0332398, including the aldehyde, ester and nitrogen based compounds... oxidation of phenol species containing moieties holding keto groups
Implementation Method 3
electrochemical pH sensing using an active redox species comprising a phenolic compound... the indicator molecule is pH sensitive and is formed by a hydroquinone based redox system having a potential that shifts with the pH
Data Source
AI summary
An electrochemical pH sensor for measuring pH in a low buffer and/or low ionic strength analyte where the electrochemical pH sensor comprises an electrode coupled with a phenolic redox species and the chemistry of the redox species provides for hydrogen bonding to one or more sulphur atoms of the redox species.