Reversible pH Indicator Surface for Real-Time Monitoring

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Solution Overview

Problem

Conventional pH testing methods, such as pH meters and disposable test strips, are impractical for real-time, reversible, and stable pH detection in various applications due to calibration requirements, fragility, and limited ability to detect pH changes over time.

Innovation Solution

A device with a pH indicator that changes color in response to pH changes, utilizing phenylazo compounds or fluorescent dyes covalently immobilized on a surface, allowing for detection of pH changes between pH 0 and 14, with each color in the spectrum associated with a specific pH, enabling precise and reversible pH monitoring.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If pH meters are used for pH testing, then measurement precision is improved, but device complexity and ease of operation deteriorate due to calibration requirements and fragility

Engineering Contradiction:
ImprovepH measurement precisionVSAvoiddevice complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent employs disposable pH test strips impregnated with pH-sensitive dye instead of reusable pH meters. These strips are single-use, eliminating calibration requirements and maintenance issues while providing sufficient measurement precision for the intended applications. The strips are discarded after one use, simplifying the overall system complexity.

Inventive Principle:
Principle #27Cheap short-living objects (Disposable)

Solution Approach 2:

The patent replaces the mechanical/electrical system of pH meters with a chemical-optical system. The pH-sensitive dye undergoes color change in response to pH variations, and this optical signal is detected either by the human eye or by a colorimeter, eliminating the need for complex electronic calibration and measurement systems.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

2Ease of operation

If disposable test strips are used, then ease of operation is improved, but measurement precision and reliability deteriorate due to permanent color change preventing detection of pH changes over time

Engineering Contradiction:
Improveease of operationVSAvoidreliability
Core Design Contradiction:
Ease of operationVSReliability

Solution Approach 1:

The patent employs a reversible pH indicator system where the dye can change color in response to pH changes and then return to its original state when the pH is restored. This dynamic reversibility allows continuous monitoring of pH changes over time, enabling detection of pH fluctuations in real-time rather than providing a single static measurement.

Inventive Principle:
Principle #15Dynamics

3Ease of manufacture

If conventional test methods are used, then ease of manufacture is improved, but productivity deteriorates due to inability to perform real-time monitoring

Engineering Contradiction:
Improveease of manufactureVSAvoidproductivity
Core Design Contradiction:
Ease of manufactureVSProductivity

Solution Approach 1:

The patent enables continuous pH monitoring through the use of reversible indicators that can track pH changes in real-time. This continuous monitoring capability allows for immediate detection of pH deviations, enabling prompt corrective actions in industrial processes, thereby improving productivity by preventing defects and reducing waste compared to intermittent testing methods.

Inventive Principle:
Principle #20Continuity of useful action

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

Enables real-time, reversible, and stable detection of pH changes with high sensitivity, allowing for accurate monitoring of pH levels in a broad range, overcoming the limitations of existing methods by providing a cost-effective and practical solution for various industrial and medical applications.

Implementation Method 1

the pH indicator changes colour in response to change in pH

Methodology Applied
Scientific EffectAcid-base reaction: Chemical Bonding

Implementation Method 2

the pH indicator is able to detect the pH between about pH 0 and about pH 14 and indicates changes in pH by way of a colour change along a colour spectrum

Methodology Applied
Scientific EffectpH-induced color change: Photochromism

Implementation Method 3

In some embodiments, the pH indicator is a fluorescent dye

Methodology Applied
Scientific EffectFluorescence: Fluorescence

Data Source

PatentEP3055689B1Ph indicator device and method for measuring a ph
Publication Date: 2022.04.13 SMITH & NEPHEW PLC
  • EP3055689B1 patent drawingFigure 1~1B
  • EP3055689B1 patent drawingFigure 2~2B
  • EP3055689B1 patent drawingFigure 3

AI summary

Disclosed herein are devices and methods for determining the pH of fluid. Example devices include a device comprising a surface configured to contact the fluid and a pH indicator covalently bound thereto, wherein the pH indicator has a first colour prior to contact with the fluid and changes colour as a function of the pH of the fluid.