Reflection-Based Optical Sensor for Hematocrit Measurement

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Solution Overview

Problem

Conventional methods for measuring hematocrit and free hemoglobin concentration in blood are prone to errors due to light scattering by air bubbles and require access to opposing sides of the fluid path, which is not always feasible, especially in systems where whole blood is separated into its constituents.

Innovation Solution

A method using a broadband light source to emit light onto a fluid, with the reflected light analyzed to produce an optical spectrum, allowing for the determination of hematocrit or free hemoglobin concentration without the need for opposing access, using a colorimetric optical sensor device that includes a broadband light source, optical spectrometer, and controller to differentiate wavelengths and correlate them to concentration levels.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If transmission-based optical methods are used to measure hematocrit or free hemoglobin concentration, then measurement can be performed, but light scattering by air bubbles causes measurement errors and opposing side access is required

Engineering Contradiction:

Improvemeasurement accuracyVSAvoidlight scattering by air bubbles

Core Design Contradiction:

Measurement precisionVSObject-affected harmful factors

Solution Approach 1:

The patent inverts the conventional transmission-based optical measurement approach by using reflection-based measurement instead. The optical sensor device directs light onto the fluid and measures the reflected light, eliminating the need for opposing side access and reducing susceptibility to air bubble interference that plagues transmission methods.

Inventive Principle:

Principle #13The other way round (Inversion)

Solution Approach 2:

The patent introduces a reflection interface as an intermediary between the light source and detector. By measuring reflected light rather than transmitted light, the system creates an indirect measurement path that avoids direct interaction with air bubbles in the fluid path, thereby reducing measurement errors.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Ease of operation

If transmission-based optical methods are used, then blood constituent analysis can be performed, but access to opposing sides of the fluid path is required which is not always feasible

Engineering Contradiction:

Improveaccess requirementVSAvoidopposing side access structure

Core Design Contradiction:

Ease of operationVSDevice complexity

Solution Approach 1:

Inventive Principle:

Principle #13The other way round (Inversion)

3Measurement precision

If conventional free hemoglobin measurement assays are used, then accurate measurement can be obtained, but the process is time-consuming and costly

Engineering Contradiction:

Improvefree hemoglobin measurement accuracyVSAvoidmeasurement time

Core Design Contradiction:

Measurement precisionVSLoss of time

Solution Approach 1:

The patent replaces complex chemical assays with a simplified optical measurement system. By using reflection-based spectroscopy to measure free hemoglobin concentration, the system eliminates time-consuming chemical reactions and complex assay procedures while maintaining measurement accuracy.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent changes the measurement parameter from chemical concentration analysis to optical reflection characteristics. By measuring how light reflects off the fluid and analyzing the spectral properties, the system can determine free hemoglobin concentration without using chemical reagents or complex assay procedures.

Inventive Principle:

Principle #35Parameter changes

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 provides accurate and reliable measurements of hematocrit and free hemoglobin concentrations, reducing errors from air bubbles and eliminating the need for opposing access, thus improving the efficiency and practicality of blood component separation processes.

Implementation Method 1

The fluid in the vessel is exposed to light from a broadband light source so as to cause at least a portion of the light to be reflected by the fluid

Methodology Applied

Scientific EffectReflection: Reflection

Implementation Method 2

Different blood constituents absorb different wavelengths of light to different degrees, which may be used to determine certain characteristics of a fluid

Methodology Applied

Scientific EffectAbsorption Spectroscopy: Absorption Spectroscopy

Data Source

PatentEP3553498B1Optical detection and measurement of hematocrit and free hemoglobin concentration

Publication Date: 2021.06.02 FENWAL INC

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AI summary

A colorimetric optical sensor device includes a broadband light source configured to emit a light that is exposed to a fluid in a vessel. At least a portion of the light is reflected off of the fluid and received by an optical spectrometer. The optical spectrometer analyzes at least a portion of the received light to determine a main wavelength of the light. A controller correlates the main wavelength to a corresponding hematocrit or free hemoglobin concentration and generates an output indicative of the hematocrit or the free hemoglobin concentration of the fluid. The hematocrit or free hemoglobin concentration information may be used by a separation assembly in which the colorimetric optical sensor device may be incorporated to modify a separation procedure in which the monitored fluid is to be separated or is a component or constituent of a previously separated biological fluid.