Rotatable Fabry-Perot Etalon Gas Sensor
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Solution Overview
Problem
Current gas sensors face challenges in distinguishing between harmful and benign gases due to high sensitivity leading to false positives and false negatives, and contamination issues, which can be dangerous in environments like homes and industrial settings.
Innovation Solution
A gas sensing device utilizing high resolution infrared spectroscopy with a broad spectrum emitter, a multilayer Fabry-Perot etalon for wavelength selection, and a sensitive detector to unambiguously identify gas species by comparing measured spectra with documented absorption spectra.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If chemical receptor systems are used to detect target gases with high sensitivity, then sensitivity to trace gases is improved, but false positives occur due to cross-sensitivity with abundant gases like CO2
Solution Approach 1:
The spectrum is segmented into multiple wavelength bands, with each band targeting a specific gas species. Instead of using a single chemical receptor that responds to multiple gases, the system divides the detection task across multiple spectral regions, allowing selective measurement of absorption features unique to each gas.
Solution Approach 2:
Different wavelength bands are assigned to detect different gas species based on their unique absorption characteristics. The system applies local quality by tailoring the detection approach to the specific spectral fingerprint of each gas, rather than using a uniform detection method for all gases.
2Measurement precision
If chemical receptor systems are used for gas detection, then sensitivity is improved, but contamination causes loss of sensitivity and false negatives
Solution Approach 1:
The patent replaces chemical receptors with an optical detection system based on infrared absorption spectroscopy. This substitution eliminates the contamination issues inherent in chemical systems while maintaining high sensitivity through precise spectral measurement.
3Difficulty of detecting and measuring
If resonant beam structures are used to determine molecular mass, then detection capability is improved, but difficulty in separating target molecules from contaminants and desorbing strongly adhered molecules increases
Solution Approach 1:
The system uses infrared absorption spectroscopy to detect the 'optical color' or spectral fingerprint of each gas molecule. By measuring which wavelengths are absorbed, the system identifies gas species based on their unique spectral signatures rather than relying on mass measurement or chemical binding.
4Measurement precision
If combustion sensors are used to detect combustible gases, then detection of trace impurities is improved, but system lifetime and reliability deteriorate due to high operating temperatures
Solution Approach 1:
The patent replaces the thermal combustion process with an optical absorption measurement system. This substitution eliminates the need for high-temperature operation, thereby extending sensor lifetime and improving reliability while maintaining trace gas detection capability.
5Measurement precision
If chemical Field Effect Transistors are used for gas detection, then sensitivity is improved through FET gain, but strongly bonded contaminants survive even at high temperatures and cause false readings
Solution Approach 1:
The patent replaces the chemical FET approach with direct optical absorption measurement. This eliminates the need for chemical binding and high-temperature desorption cycles, avoiding the contaminant survival issue while maintaining sensitivity through precise spectral detection.
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 provides high specificity and sensitivity for gas detection, reducing the risk of false readings and ensuring accurate identification of gases, such as CO2, without interference from abundant gases like CO2, and is robust and cost-effective.
Implementation Method 1
a multilayer Fabry-Perot etalon for wavelength selection
Implementation Method 2
high resolution infrared spectroscopy with a broad spectrum emitter, a multilayer Fabry-Perot etalon for wavelength selection
Implementation Method 3
high resolution infrared spectroscopy to detect and identify small gas molecules. The spectrum of thousands of small molecules is well documented. These spectra provide a fingerprint of each compound
Implementation Method 4
high resolution infrared spectroscopy with a broad spectrum emitter
Data Source
AI summary
Systems and methods for forming a compact gas sensor include a multilayer etalon as a wavelength discriminating element. The position of the etalon may be adjusted to tune its transmission profile. And embodiment directed to carbon dioxide detection is described.