Formaldehyde Gas Analyser Using UV Absorption and NO2 Interference Correction
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Solution Overview
Problem
Current gas sensors for detecting formaldehyde in enclosed environments face challenges due to the need for continuous real-time measurements, high costs, and interference from other gases absorbing light in similar wavelength ranges, making it difficult to accurately measure formaldehyde concentrations safely and efficiently.
Innovation Solution
A gas analyser using ultraviolet light sources and detectors with specific wavelength ranges (337.5nm to 346nm and 325nm to 332nm) and a nitrogen dioxide sensor to account for interference, allowing for accurate formaldehyde measurement by calibrating for light intensity and nitrogen dioxide absorption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If gas chromatography is used to detect formaldehyde, then measurement accuracy is improved, but measurement time increases and real-time monitoring becomes impossible
Solution Approach 1:
The patent replaces the mechanical gas chromatography system with an optical absorption spectroscopy system using a photodiode array detector. This substitution enables direct optical measurement of formaldehyde absorption at 337.5-346nm without requiring physical separation through a column, achieving both high accuracy and real-time measurement capability simultaneously.
2Measurement precision
If high resolution spectrometers are used for optical absorption spectroscopy, then measurement precision is improved, but device cost increases
Solution Approach 1:
The patent replaces expensive high-resolution spectrometers with a simpler, more affordable photodiode array system. The photodiode array directly detects UV light absorption at the formaldehyde wavelength range without requiring complex spectral resolution equipment, significantly reducing device cost while maintaining sufficient measurement precision for formaldehyde detection.
Solution Approach 2:
The patent changes the detection parameter from full-spectrum high-resolution analysis to targeted detection at specific wavelength ranges (337.5-346nm for formaldehyde, plus reference ranges). This parameter optimization allows using simpler optical components that are tuned to specific wavelengths rather than requiring broad-spectrum high-resolution spectrometers.
3Difficulty of detecting and measuring
If standard optical absorption techniques are used to measure formaldehyde, then detection capability is improved, but measurement accuracy deteriorates due to interference from other gases
Solution Approach 1:
The patent segments the detection process into multiple independent wavelength range measurements: formaldehyde measurement range (337.5-346nm), first reference range (332-337nm or 347-350nm), and second reference range (356-370nm). Each range targets specific absorbers, allowing the system to distinguish formaldehyde from interferents like NO2, O3, and aldehydes by comparing absorption patterns across these segmented wavelength bands.
Solution Approach 2:
The patent introduces reference wavelength ranges as intermediary measurements that detect interfering substances without detecting formaldehyde. By measuring absorption in these reference ranges and using them to correct the formaldehyde measurement, the system effectively eliminates interference from gases like nitrogen dioxide, ozone, and other aldehydes that absorb in overlapping wavelength regions.
4Adaptability or versatility
If multiple optical components are used in gas sensors, then measurement capability is improved, but device cost and light attenuation increase
Solution Approach 1:
The patent merges the functions of multiple separate optical components into a single integrated photodiode array system. Instead of using separate detectors for different wavelength ranges with beam splitters and filters, the photodiode array simultaneously detects UV light across multiple wavelength ranges in one component, reducing device complexity and light loss while maintaining full measurement capability.
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 affordable, real-time, and sensitive formaldehyde concentration monitoring in enclosed spaces, effectively overcoming the limitations of existing technologies by using narrow wavelength ranges and independent nitrogen dioxide measurements to minimize interference.
Implementation Method 1
measuring the absorption of light in the specific range of wavelengths absorbed by formaldehyde (250nm to 360nm)
Implementation Method 2
a detector configured to receive ultraviolet light emitted by the at least one ultraviolet light source and passed through the sample chamber
Data Source
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AI summary
A gas analyser is provided to measure the concentration of formaldehyde within enclosed environments such as within buildings comprising an ultraviolet light source (102), a sample chamber (104), a detector (112, 114). The detector measures the intensity of light received by photosensors within a measurement range of wavelengths, and at least one reference range of wavelengths. Advantageously, the concentration of formaldehyde is determined taking into account fluctuations in the intensity of light emitted by the light source, and in the presence of any interferents such as nitrogen dioxide. A method of measuring the concentration of formaldehyde in enclosed environments is also presented.