Photoluminescent Oxygen Probe Humidity Cross-Sensitivity
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Solution Overview
Problem
Optical oxygen sensors based on polymeric materials exhibit significant cross-sensitivity to humidity, limiting their use in uncontrolled humidity environments, which hampers their reliability and acceptance for measuring oxygen concentrations in various applications.
Innovation Solution
A microporous wettable polyolefin support layer, specifically a non-woven spinlaid or spunbond polypropylene fabric with hydrophilic pendant groups, is used in conjunction with an oxygen-sensitive photoluminescent dye embedded within an oxygen-permeable polymer matrix to form a thin film coating, reducing humidity cross-sensitivity and enhancing luminescent signal intensity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a light-scattering additive (e.g., TiO2) or underlayer is incorporated to increase photoluminescent signals, then the reliability of optical measurements is improved, but cross-sensitivity to humidity increases significantly
Solution Approach 1:
The patent employs a microporous polypropylene support layer with controlled porosity (30-80% open space) that allows oxygen permeation while providing a hydrophobic barrier to humidity. The porous structure enables the photoluminescent dye to access oxygen molecules for measurement while the hydrophobic nature of polypropylene repels water vapor, thus eliminating humidity cross-sensitivity that plagues conventional sensors using hydrophilic materials like TiO2
Solution Approach 2:
The invention creates a composite structure combining a microporous polypropylene support layer with an oxygen-permeable polymer matrix containing the photoluminescent dye. This composite approach integrates the hydrophobic, oxygen-permeable properties of polypropylene with the optical sensing capabilities of the dye-matrix system, achieving both high signal intensity and humidity insensitivity simultaneously
2Object-affected harmful factors
If a microporous polypropylene support layer with hydrophobic properties is used, then cross-sensitivity to humidity is reduced, but the luminescent signal intensity may be compromised without proper matrix selection
Solution Approach 1:
The patent optimizes the oxygen permeability parameter of the polymer matrix to ensure adequate oxygen transport to the photoluminescent dye while maintaining signal intensity. By selecting matrices with appropriate oxygen diffusion coefficients and adjusting dye concentration within the matrix, the system achieves strong luminescent signals despite using a hydrophobic polypropylene support that limits water vapor interaction
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 solution significantly reduces humidity cross-sensitivity, allowing for accurate and reliable measurement of oxygen concentrations with minimal change in luminescence lifetime, even under varying humidity conditions, thereby improving the sensor's performance and reliability.
Implementation Method 1
oxygen-sensitive photoluminescent dye applied onto a first major surface of said support layer (30) forming a thin film coating on the support layer
Implementation Method 2
microporous wettable polyolefin support layer (30)... a non-woven spinlaid or spunbond polypropylene fabric with hydrophilic pendant groups
Data Source
Figure 1
AI summary
An oxygen-sensitive probe having reduced cross-sensitivity to humidity and methods of manufacturing and using such probes to measure oxygen concentrations within an enclosed space. The probe includes a thin film of an oxygen-sensitive photoluminescent dye on a first major surface of a microporous wettable polyolefin support layer. The dye is preferably a solid state composition comprising the oxygen-sensitive photoluminescent dye embedded within an oxygen-permeable hydrophobic polymer matrix.