Colorimetric Analyzer Obstruction Detection via Dual-Wavelength Ratio
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Solution Overview
Problem
In online colorimetric analyzers, incomplete filling of the measurement cell can lead to a water/air interface, causing illumination obstruction and resulting in inaccurate absorbance and concentration readings due to changes in light intensities.
Innovation Solution
A colorimetric analyzer is designed to detect and correct for illumination obstructions by calculating a sensitivity ratio using multiple wavelength absorbance measurements and comparing it to threshold values to determine the presence of an obstruction, allowing for accurate concentration calculations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple wavelength measurements are used to calculate sensitivity ratio for obstruction detection, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The measurement process is segmented into distinct wavelength channels (first wavelength and second wavelength), with each wavelength independently measuring absorbance at its specific wavelength. This segmentation allows the system to detect obstructions by comparing ratios of absorbance across different wavelengths, improving measurement precision without requiring a single complex measurement system.
Solution Approach 2:
The illumination source is designed to provide multiple wavelengths simultaneously, and the illumination detector is configured to measure absorbance at multiple wavelengths. This multi-functional approach allows a single measurement system to perform both obstruction detection and concentration measurement functions, improving precision while managing device complexity through unified hardware design.
2Reliability
If sensitivity ratio calculation with threshold comparison is implemented, then reliability of concentration measurements is improved, but calculation complexity increases
Solution Approach 1:
The system pre-calculates a sensitivity ratio from absorbance measurements at multiple wavelengths and compares this ratio against predetermined thresholds before final concentration determination. This preliminary action of ratio calculation and threshold comparison filters out measurements affected by obstructions, improving reliability by preventing erroneous concentration readings from being reported.
Solution Approach 2:
The system transforms raw absorbance measurements into a derived parameter (sensitivity ratio) that is more robust to certain types of errors. By changing the measurement parameter from direct absorbance to a ratio of absorbances at different wavelengths, the system improves reliability while the computational complexity remains manageable through straightforward mathematical operations.
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
This approach ensures repeatable and accurate concentration readings by identifying and accounting for illumination obstructions, thereby improving the reliability of analyte concentration measurements in colorimetric assays.
Implementation Method 1
an analyte's absorbance can be measured as a logarithmic ratio of two measured light intensities
Implementation Method 2
A concentration of the analyte can be calculated using a detected absorbance of the complex in accordance with Beer-Lambert's Law
Data Source
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AI summary
A colorimetric analyzer (100) includes a reaction chamber (118) configured to receive a sample and at least one reagent. A measurement cell is operably coupled to the reaction chamber (118). The colorimetric analyzer (100) has an illumination source (116) configured to emit illumination at a first wavelength (204) during a first absorbance measurement and at a second wavelength (208) during a second absorbance measurement. The colorimetric analyzer (100) also includes an illumination detector (114) spaced from the illumination source (116) such that illumination from the illumination source (116) passes through the measurement cell to the illumination detector (114). A controller (102) is coupled to the illumination source (116) and the illumination detector (114). The controller (102) is configured to detect an obstruction of light between the illumination source (116) and the illumination detector (114) based on the first and the second absorbance measurements.