MOF FBG Sensor for High-Temperature Measurement
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Solution Overview
Problem
Conventional fiber Bragg grating (FBG) based temperature sensors have a maximum operating temperature limit of around 500°C due to thermal annealing, making them unsuitable for high-temperature applications such as smelting and furnace operations where temperatures can exceed 1000°C, and they lack multiplexed sensing capabilities.
Innovation Solution
A microstructured optical fiber (MOF) based temperature sensor with a suspended core configuration and a fiber Bragg grating (FBG) written using a femtosecond laser to create periodic refractive index modulations in the form of nanoholes, allowing for temperature measurement up to at least 1350°C by utilizing high-purity fused silica material that maintains structural integrity beyond the softening point of silica.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional FBG sensors are used, then manufacturing precision and measurement precision are improved, but the maximum operating temperature is limited to around 500°C due to thermal annealing
Solution Approach 1:
The patent changes the fundamental material parameter from photosensitive fiber to high-purity fused silica, which has a significantly higher thermal stability threshold. This parameter change allows the FBG sensor to operate at temperatures exceeding 1000°C without thermal annealing, directly resolving the temperature limitation while preserving measurement precision
Solution Approach 2:
The patent employs a composite structure combining high-purity fused silica material with FBG technology. The fused silica provides exceptional thermal stability and structural integrity at high temperatures, while the FBG embedded within maintains the precision temperature sensing capability, achieving both high-temperature resistance and accurate measurement
2Temperature
If standard electrical thermocouples are used in high-temperature environments, then temperature measurement is possible, but they cannot survive more than a few minutes in highly corrosive and hot environments
Solution Approach 1:
The patent replaces the electrical thermocouple system with an optical fiber-based FBG sensor system. This substitution eliminates the electrical components that are vulnerable to corrosion and high-temperature damage, while the optical fiber and fused silica construction provide exceptional chemical and thermal stability, enabling long-term reliable operation in corrosive high-temperature environments
Solution Approach 2:
The high-purity fused silica material creates an inherently inert and chemically resistant environment for the FBG sensor. This material resistance to chemical corrosion protects the sensor from degradation in highly corrosive atmospheres, dramatically improving reliability and operational lifespan compared to electrical thermocouples
3Adaptability or versatility
If conventional FBG sensors are used, then multipoint sensing capability is achieved, but they are unsuitable for high-temperature applications above 500°C
Solution Approach 1:
The patent changes the material composition parameter from photosensitive fiber to high-purity fused silica, which fundamentally raises the temperature threshold for thermal annealing. This enables multiplexed FBG sensors to maintain their wavelength division multiplexing capability at temperatures above 1000°C, extending the operating temperature range while preserving multipoint sensing functionality
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 MOF FBG sensor effectively measures elevated temperatures up to 1350°C with improved durability and multiplexing capabilities, enabling precise temperature control in high-temperature environments without the limitations of conventional FBG sensors.
Implementation Method 1
a fiber Bragg grating (FBG) written using a femtosecond laser to create periodic refractive index modulations
Implementation Method 2
create periodic refractive index modulations in the form of nanoholes
Implementation Method 3
a fiber Bragg grating (FBG) written using a femtosecond laser to create periodic refractive index modulations in the form of nanoholes
Implementation Method 4
an optical sensor interrogator to detect the reflected wavelength
Data Source
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AI summary
A temperature sensor and temperature sensing system for sensing changes m temperature up to a predetermined temperature is disclosed. The temperature sensor includes a microstructured optical fiber where the microstructured optical fiber includes a plurality of longitudinal channels extending along the microstructured optical fiber. The sensor also includes a fiber Bragg grating formed in the microstructured optical, fiber by generating a periodic modulation in the refractive index along a core region of the microstructured optical fiber. The fiber Bragg grating is operable to produce band reflection at a reflection wavelength that varies in accordance with changes in temperature at the core region of the optical fiber.