In Vitro Blood Concentration Detection via Path Length Correction
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Solution Overview
Problem
Existing photometric methods for determining component concentrations in samples, such as blood, face inefficiencies due to the need for frequent calibrations when sample chamber dimensions are unstable or vary, especially when using shorter-life or less precisely manufactured chambers, and require improved precision for accurate in vitro analysis.
Innovation Solution
An apparatus that calculates the concentration of a component based on absorbance measurements at specific wavelengths, with a correction term applied to account for the bias from certain blood components like hemoglobin, allowing for a more precise determination of the radiation path length and concentration, using a model that adjusts for the impact of these components on absorbance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If sample chambers are manufactured with larger tolerances or have shorter lifetime, then manufacturing cost is reduced, but path length stability deteriorates requiring frequent calibrations
Solution Approach 1:
The system performs self-calibration by using the absorbance of a known component (water or buffer) at a second wavelength to automatically determine the path length. This eliminates the need for external calibration procedures and manual intervention, allowing the system to compensate for path length variations inherent in lower-cost chambers without requiring frequent operator calibration.
2Ease of operation
If path length is determined using water content in blood samples, then measurement simplicity is improved, but measurement precision deteriorates due to bias from hemoglobin constituents
Solution Approach 1:
The method separates the determination of path length from the determination of analyte concentration by using two different wavelengths. The path length is extracted and determined independently using the absorbance of water or buffer at a second wavelength, while the analyte concentration is determined at a first wavelength. This extraction eliminates the interference of hemoglobin that would otherwise contaminate the path length measurement.
Solution Approach 2:
The patent introduces water or buffer as an intermediary substance whose absorbance properties are used to determine the path length. This intermediary serves as a reference that is not affected by hemoglobin interference, allowing accurate path length determination that can then be applied to the measurement of other constituents in the blood sample.
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 enables more accurate and precise determination of component concentrations by correcting for the inaccuracy in path length estimation, improving measurement precision and reducing the need for frequent calibrations, especially in in vitro blood analysis.
Implementation Method 1
measuring absorbance of radiation by the sample
Implementation Method 2
The Lambert-Beer's law applies to optical measurements where the transmission of radiation from a radiation source through a sample is determined by a detector, i.e. the absorbance is proportional to the concentration of absorbing species in the sample as well as to the sample thickness
Data Source
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AI summary
An apparatus for detecting a first component in a sample (104), the first component being responsive to at least radiation (113) of a first wavelength, the sample comprising the first component and a second component responsive to at least radiation (114) of a second wavelength, the apparatus comprising: at least one radiation source (101,102) configured to direct radiation (113,114) towards the sample; at least one radiation detector (106,107) configured to detect radiation (116,117) of at least the first and the second wavelength, said detected radiation having propagated along a radiation path through at least a portion of the sample; and a processing unit (108) operable to receive at least one detector signal from the at least one radiation detector indicative of the detected radiation, and to determine an estimated path length of the radiation path at least from a determined absorbance by the sample of radiation at the second wavelength; determine an estimated concentration of the first component at least from a determined absorbance by the sample of radiation at the first wavelength and from the estimated path length; determine a corrected concentration of the first component at least from the estimated concentration and from a correction term indicative of a corrected path length corrected for a presence of the first component using the estimated concentration.