Optical pH Sensor Layered Structure for Indicator Bleeding
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Solution Overview
Problem
Existing optical sensors for determining hydrogen ion concentration, such as pH, are affected by the presence of other dyes, reactivity with sample components, lipids, and salts, particularly in complex compositions like food and nutrient products, leading to inaccurate measurements and indicator bleeding.
Innovation Solution
An optical H+ sensor with an H+ indicator material situated between a support material and a layered structure comprising a hydrophilic and cation exchange layer, allowing H+ permeability while minimizing indicator dye bleeding and maintaining reactivity, suitable for use in complex compositions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If the indicator dye is immobilized in a hydrophilic homogeneous non-fibrous accommodating layer, then the mechanical stability is improved, but the indicator dye may still bleed in complex compositions containing other dyes, reactivity with sample components, lipids, and salts
Solution Approach 1:
The sensor membrane is divided into multiple functional layers: a support element, a hydrophilic homogeneous non-fibrous accommodating layer containing the immobilized indicator dye, and an outer protective layer. This segmentation allows each layer to perform its specific function - the accommodating layer provides mechanical stability while the protective layer prevents bleeding and interference from complex sample components.
Solution Approach 2:
The hydrophilic homogeneous non-fibrous accommodating layer acts as an intermediary between the indicator dye and the sample. It immobilizes the dye in a controlled environment that prevents direct contact with interfering substances in complex compositions, thereby preventing bleeding while maintaining dye reactivity to H+ ions.
2Loss of energy
If the indicator dye is made reactive to H+ ions, then the sensitivity is improved, but the reactivity with other sample components, lipids, and salts increases leading to inaccurate measurements
Solution Approach 1:
The indicator dye is immobilized in a hydrophilic homogeneous non-fibrous accommodating layer with specific local properties. This layer creates a localized environment that maintains the dye's sensitivity to H+ ions while excluding other interfering sample components, lipids, and salts through its selective permeability and structural characteristics.
Solution Approach 2:
The hydrophilic homogeneous non-fibrous accommodating layer has a controlled porous structure that allows H+ ions to access the immobilized indicator dye while restricting the penetration of larger interfering molecules, lipids, and salts. This selective porosity maintains sensitivity while reducing interference.
3Adaptability or versatility
If the sensor is designed for use in complex compositions like food and nutrient products, then the adaptability is improved, but the indicator bleeding and measurement accuracy deteriorate
Solution Approach 1:
The sensor membrane design incorporates multiple functional layers that collectively provide universal applicability to complex compositions. The hydrophilic homogeneous non-fibrous accommodating layer with immobilized indicator dye, combined with the protective outer layer, creates a multi-functional structure that maintains measurement accuracy across diverse samples including food and nutrient products containing other dyes, lipids, and salts.
4Device complexity
If the sensor membrane structure is simplified, then the device complexity is reduced, but the prevention of indicator bleeding and maintenance of selectivity become difficult
Solution Approach 1:
The hydrophilic homogeneous non-fibrous accommodating layer combines multiple functions into a single integrated layer: it provides mechanical support, immobilizes the indicator dye, prevents bleeding, and maintains selectivity. This merging of functions achieves reliable indicator stability without significantly increasing overall device complexity.
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 robust, accurate, and sensitive measurements of hydrogen ion concentration across various conditions, including elevated temperatures, with reduced bleeding of indicator dye and improved selectivity, dynamic range, accuracy, and reproducibility, making it suitable for complex samples like food and nutrient products.
Implementation Method 1
a cation exchange layer, which is in contact with the indicator material on the other side from the hydrophilic layer
Implementation Method 2
a hydrophilic layer, which is in contact with a product of which the H+ concentration is to be determined, of which H+ is permeable through the membrane
Implementation Method 3
an indicator material which comprises an indicator dye covalently coupled to a polymer, wherein the indicator material is situated between a support material and a layered structure
Data Source
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Figure 3~4
AI summary
The present invention relates to an optical H + -sensor, comprising an H + - indicator material, wherein the H + -indicator material is present between a support material and a H+-permeable layered structure, the layered structure comprising an H + -permeable hydrophilic layer and an H + -permeable cation exchange layer. Further, the invention relates to a method for determining the H + concentration, e.g. expressed as p H, in a product or sample thereof, the method comprising contacting the product or sample with an optical H + -sensor according to the invention, measuring an optical property of the indicator material, and determining the H + -concentration of the product or sample based on said optical property.