High-Performance Fiber Optic Carbon Dioxide Sensor for Elevated Temperature and Distributed Monitoring
This invention is a novel fiber-optic CO2 sensor utilizing a Lewis acid-base-active polymer composite thin film as its sensing layer. This sensor overcomes the critical limitations of conventional sensors by providing robust, high-sensitivity CO2 detection in the challenging elevated temperature range of 50C to 100C, making it ideal for the critical safety monitoring of energy systems.
Description
The sensor operates by leveraging a mechanism of weak chemisorption based on a Lewis acid-base interaction, which involves the controlled sharing of electron pairs between the polymer composite sensing film and CO2 molecules. Unlike traditional sensors that rely on weak, temperature-unstable physisorption (physical adsorption), this approach creates covalent bonds with an ideal adsorption enthalpy that ensures strong signal stability and responsiveness at temperatures up to 100C. The sensing layer is a specially formulated polymer composite blend (e.g., a Lewis base polymer mixed with a hydroxyl polymer matrix) that is deposited as a thin film onto an uncladded optical fiber. The matrix polymer facilitates mechanical stability and enhances CO2 transport through the film. Crucially, the sensor's performance is tunable through meticulous control of the polymer blend composition, which modifies the film's internal microphase domains. These domains generate an enhanced optical signal through wavelength-dependent light scattering upon CO2 exposure, providing a robust and optimized optical response.Applications
- Critical Energy Storage Safety: Early thermal runaway detection by monitoring CO2 off-gassing in high-capacity energy storage devices.- Electrical Grid Infrastructure: Continuous dissolved gas analysis (DGA) in distribution transformers for assessing operational and thermal warning conditions.
- Embedded Power Equipment Monitoring: Fully embedded CO2 sensing in low to medium voltage electrical power equipment where metal wires are undesirable due to safety concerns.
- Large-Scale Industrial Process Control: Distributed environmental or industrial gas monitoring across expansive or harsh environments.
- General HVAC and Air Quality: High-performance CO2 monitoring in hot or humid industrial and commercial settings.
Advantages
- Stable High-Temperature Performance: Maintains a strong, high-resolution signal throughout the critical 50C to 100C operating range, a major failing point for current commercial sensor technologies.- High Sensitivity and Strong Signal: Demonstrates a significant optical intensity change (up to 65% response to pure CO2) at elevated temperatures, providing excellent signal-to-noise ratio.
- Early Failure Detection Capability: Proven ability to detect CO2 levels across the entire range from normal operation (as low as 300 ppm detection limit) up to danger thresholds, enabling crucial pre-warning capabilities for thermal events.
- Distributed Sensing Ready: Exhibits a novel near-infrared response suitable for Optical Time-Domain Reflectometer (OTDR) interrogation, enabling large-scale, cost-effective distributed sensing over long fiber lengths.
- Optically Tunable Response: Sensor performance can be optimized for specific environments or wavelengths by simply adjusting the ratio and morphology of the polymer components in the composite blend.