FBG Optical Fiber Gas Sensor With Local Catalyst Coating
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Solution Overview
Problem
Conventional optical fiber gas sensors with uniform sensing layers around the optical fiber are labor-intensive and costly to manufacture, and forming multiple detection parts increases costs further.
Innovation Solution
An optical fiber gas sensor with a tubular case, fiber Bragg grating part, fixing member, sensing member, and sealing member, where the FBG part is coated with a catalyst and fixed to the case, allowing deformation by heat-generated reactions for high sensitivity detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the sensing member is disposed as a film having a constant thickness on all circumference of the optical fiber, then the gas detection sensitivity is improved, but the manufacturing complexity and cost increase
Solution Approach 1:
The sensing member (catalyst) is selectively disposed only in the vicinity of the FBG part rather than uniformly around the entire optical fiber. This local concentration of sensing material maximizes the interaction between the catalyst and detection object gas at the critical measurement point while significantly reducing manufacturing complexity and material usage.
2Adaptability or versatility
If multiple gas detection parts are formed in multiple positions of the same optical fiber, then the detection coverage is improved, but the manufacturing cost increases
Solution Approach 1:
A single optical fiber with one FBG part serves multiple functions: it acts as both the sensing element and the structural component. The FBG part simultaneously provides the sensing function and the structural support for mounting the catalyst, eliminating the need for additional detection parts and reducing manufacturing costs.
3Ease of manufacture
If the FBG part is coated with sensing member and fixed to the case, then the manufacturing ease is improved, but the detection sensitivity must be maintained
Solution Approach 1:
The optical fiber is fixed to the case in advance with both ends secured, creating a pre-tensioned structure. The FBG part is then coated with the sensing member in this fixed state. This preliminary fixing ensures that when the catalyst reacts with detection object gas and generates heat, the resulting expansion is directly transmitted to deform the FBG part, maintaining high detection sensitivity while simplifying the manufacturing process.
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 can be easily manufactured and detects gases with high sensitivity by varying the Bragg wavelength due to case deformation from heat reactions, reducing labor and costs.
Implementation Method 1
The sensing member is configured by a catalyst for accelerating a contact combustion reaction of detection object gas
Implementation Method 2
The sealing member is configured by a hydrophobic film that is permeable to detection object gas
Implementation Method 3
an optical fiber having a fiber Bragg grating (FBG) part
Data Source
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Figure 5
AI summary
An optical fiber gas sensor according to the present invention includes a tubular case, an optical fiber having a fiber Bragg grating (FBG) part, a fixing member, a sensing member, a through hole, and a sealing member. The fixing member fixes the optical fiber in a state where the optical fiber is along an axial direction of an inner case and tension is applied to the FBG part. The FBG part is coated with the sensing member within the inner case. The sensing member is configured by a catalyst to accelerate a contact combustion reaction of detection object gas. The through hole is disposed within a wall of the inner case. The through hole is coated with the sealing member. The sealing member is configured by a hydrophobic film being permeable to the detection object gas.