Multi-Wavelength Breath Analysis Using Split IR Bands
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Solution Overview
Problem
Breath analyzing equipment operating in the 3.3-3.6 µm wavelength range faces challenges due to high cross-sensitivity to substances, requiring complex and costly designs with multiple filters, making it unsuitable for compact, cost-effective, and robust devices like handheld or vehicle-mounted systems.
Innovation Solution
A breath analysis apparatus using a non-dispersive infrared system with a measuring cell that employs at least two concave mirrors to extend the optical path, a first and second infrared detector, and a single interference filter to separate the 3.3-3.6 µm wavelength range into two bands, allowing for absorption signal comparison to identify substances by comparing absorption values with tabulated data.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple narrow-band filters are used to distinguish between different substances in the 3.3-3.6 µm range, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent divides the 3.3-3.6 µm wavelength range into multiple distinct wavelength bands (e.g., 3.3-3.4 µm, 3.4-3.5 µm, 3.5-3.6 µm) and assigns different detectors to monitor specific absorption features within each band. This segmentation allows the system to distinguish between different substances by analyzing their unique absorption spectra across multiple bands, achieving high measurement precision without requiring a single complex filter for each substance.
Solution Approach 2:
The patent employs a single broadband infrared detector that can detect across the entire 3.3-3.6 µm range, making it a universal detector for multiple substances. By combining this universal detector with spectral analysis algorithms that process absorption patterns across multiple wavelength bands, the system achieves the ability to identify multiple different substances (ethyl alcohol, acetone, methyl alcohol, etc.) without requiring separate specialized detectors for each substance.
2Adaptability or versatility
If a chopper wheel with multiple optical filters is used, then substance discrimination capability is improved, but ease of operation deteriorates
Solution Approach 1:
The patent replaces the mechanical chopper wheel system with a stationary optical arrangement using multiple fixed broadband bandpass filters positioned in front of different detectors. This eliminates moving parts and mechanical complexity while maintaining the ability to discriminate between different substances. The system achieves substance discrimination through the spectral selectivity of the fixed filters and detectors rather than through mechanical modulation, making it more suitable for field use in handheld or vehicle-mounted devices.
3Measurement precision
If the wavelength range 3.3-3.6 µm is used for breath analysis, then sensitivity is improved, but cross-sensitivity to interfering substances increases
Solution Approach 1:
The patent segments the 3.3-3.6 µm wavelength range into multiple distinct bands and uses multiple detectors to monitor absorption features in each band. By analyzing the pattern of absorption across multiple bands rather than relying on a single wavelength, the system can distinguish between the absorption signature of the target substance (e.g., ethyl alcohol) and interfering substances (e.g., acetone, methyl alcohol), thereby maintaining high sensitivity while reducing cross-sensitivity through spectral pattern recognition.
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
Enables accurate and reproducible identification of substances like ethyl alcohol and other interfering substances in a compact format, using less costly components and simplifying the design, while maintaining robustness and efficiency.
Implementation Method 1
breath analysis apparatus for non-dispersive breath analysis operating in a preselected wavelength range of an unidentified substance
Implementation Method 2
at least two concave mirrors arranged to control an infrared beam from said source to traverse the cell multiple times
Implementation Method 3
a first interference filter with a first characteristic transition wavelength combined with a first infrared detector arranged in the optical path and configured to transmit a first wavelength band within the preselected wavelength range through the filter to the first infrared detector while reflecting a second wavelength band
Data Source
Figure 1
Figure 2
Figure 3a~3c
AI summary
The present invention relates to a breath analyzing apparatus and method. In particular the invention relates to a breath analyzing apparatus operating in the 3.3-3.6 μm wavelength range and arranged to provide absorption information in at least two different wavelength bands in the wavelength range. The absorption information from the wavelength bands are compared with tabulated data of preselected substances to identify an unidentified substance.