Fiber Optic Gas Sensor Using Optical Heating for Hydrogen Detection
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Solution Overview
Problem
Existing fiber optic sensors for hydrogen detection face challenges in operating effectively across a wide temperature range, particularly at low temperatures, due to palladium's slow hydrogen absorption rate, resulting in low sensitivity and slow response time.
Innovation Solution
An optical fiber system that includes a wavelength resonant in-fiber optic component, such as a fiber Bragg grating, with a palladium or palladium alloy layer that absorbs hydrogen, where a power light is used to heat the material, increasing the hydrogen absorption rate and sensitivity, especially at low temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a palladium layer is used for hydrogen absorption at low temperatures, then the sensor maintains operational capability, but the hydrogen absorption rate becomes slow resulting in low sensitivity and slow response time
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting the temperature of the palladium layer through optical heating. By changing the temperature parameter from low to elevated levels, the hydrogen absorption rate increases significantly, resolving the contradiction between maintaining operational capability at low temperatures and achieving high absorption rates. The system selectively heats the palladium layer only when hydrogen detection is needed.
Solution Approach 2:
The patent implements periodic action by using pulsed optical heating of the palladium layer. Instead of continuous heating, the system applies periodic thermal energy through optical pulses, which enhances hydrogen absorption during the heated phases while allowing cooling during off phases. This periodic thermal stimulation maintains high absorption rates without requiring continuous high energy input.
2Productivity
If electrical heating is used to increase hydrogen absorption rate, then the absorption rate improves, but additional electrical cabling is required which increases device complexity and manufacturing cost
Solution Approach 1:
The patent replaces the electrical heating system with an optical heating system. Instead of using electrical cables and resistive heating elements, the system uses optical fibers to deliver light energy that is converted to thermal energy in the palladium layer. This substitution eliminates the need for electrical cabling while achieving the same heating effect, thereby reducing device complexity and manufacturing cost.
Solution Approach 2:
The patent introduces an optical fiber as an intermediary to transfer energy from a remote light source to the palladium layer. The optical fiber serves as a mediator that delivers thermal energy without requiring direct electrical contact with the sensor location. This intermediary approach allows heating functionality to be achieved through a non-electrical pathway, simplifying the overall system architecture.
3Loss of time
If electrical heating elements are installed on the fiber to increase absorption rate, then the response time improves, but the sensor becomes less immune to electromagnetic radiation and more susceptible to harmful factors
Solution Approach 1:
The patent replaces electrical heating elements with optical heating through fiber-delivered light. This substitution maintains the rapid response time benefit of active heating while eliminating the vulnerability to electromagnetic radiation. The optical fiber and palladium layer combination provides electromagnetic immunity while achieving fast hydrogen absorption kinetics through optically-induced thermal effects.
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 system enhances the sensitivity and response time of hydrogen detection, particularly at low temperatures, by using in-fiber light to heat the palladium layer, allowing for rapid hydrogen absorption and detection.
Implementation Method 1
the material is a material, such as palladium or a palladium alloy, that is able to absorb the gas being sensed (e.g., hydrogen)
Implementation Method 2
the optical fiber is structured to allow at least a portion of the power light to be used to heat the material
Implementation Method 3
at least a portion of the power light to be released from the optical fiber at the first location and be absorbed by the material. The absorbed power light heats the material
Implementation Method 4
An FBG reflects a spectral peak of a light back through the fiber toward the light source, and the particular spectral peak (called the resonance wavelength) that is reflected depends upon the grating spacing
Implementation Method 5
The material induces a strain in the optical fiber when the material absorbs the gas, with a magnitude of the strain being dependent upon an amount of the gas that is absorbed. The strain in the optical fiber changes the characteristic, e.g., grating spacing
Data Source
AI summary
A gas sensor includes an in-fiber resonant wavelength device provided in a fiber core at a first location. The fiber propagates a sensing light and a power light. A layer of a material is attached to the fiber at the first location. The material is able to absorb the gas at a temperature dependent gas absorption rate. The power light is used to heat the material and increases the gas absorption rate, thereby increasing sensor performance, especially at low temperatures. Further, a method is described of flash heating the gas sensor to absorb more of the gas, allowing the sensor to cool, thereby locking in the gas content of the sensor material, and taking the difference between the starting and ending resonant wavelengths as an indication of the concentration of the gas in the ambient atmosphere.