Non-invasive Hematocrit Monitoring via Optical Ratiometry

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Solution Overview

Problem

Current methods for measuring hematocrit levels require invasive blood sampling and in vitro analysis, necessitating patient visits to healthcare facilities for each measurement.

Innovation Solution

A non-invasive method and system for monitoring hematocrit levels in vivo, using a medical device with a light emitter and photodetectors to provide incident light to patient tissue and monitor emission responses at specific wavelengths, calculating a ratiometric value to determine hematocrit levels.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If in vitro blood analysis methods are used, then measurement precision is improved, but patient convenience deteriorates due to repeated facility visits

Engineering Contradiction:

Improvehematocrit measurement precisionVSAvoidpatient convenience

Core Design Contradiction:

Measurement precisionVSEase of operation

Solution Approach 1:

The patent replaces the mechanical/invasive blood sampling system with an optical measurement system. Light emitters illuminate the patient's skin and underlying blood vessels, and photodetectors detect the transmitted or reflected light. The optical properties of blood (absorption, scattering) are analyzed to determine hematocrit levels, eliminating the need for needle punctures and laboratory processing while maintaining measurement accuracy.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent introduces light as an intermediary medium to indirectly measure hematocrit. Instead of directly analyzing blood samples, the system uses light interaction with blood through tissue as a mediator. The optical signals carry information about blood composition, allowing non-invasive determination of hematocrit levels by analyzing how light propagates through the tissue-blood interface.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If in vitro blood sampling is performed, then reliable hematocrit data is obtained, but measurement time and patient burden increase

Engineering Contradiction:

Improvehematocrit data reliabilityVSAvoidmeasurement time

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The patent replaces the time-consuming mechanical process of blood collection, transport, and laboratory analysis with an instantaneous optical measurement system. The device performs hematocrit measurement in real-time by analyzing light interaction with blood through the skin, reducing the measurement process from hours (including facility visits) to seconds while maintaining data reliability through validated optical algorithms.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Productivity

If repeated blood draws are conducted, then continuous monitoring capability is achieved, but patient discomfort and infection risk increase

Engineering Contradiction:

Improvecontinuous monitoring capabilityVSAvoidpatient discomfort and infection risk

Core Design Contradiction:

ProductivityVSObject-affected harmful factors

Solution Approach 1:

The patent replaces repeated mechanical blood draws with a non-invasive optical monitoring system. The device can continuously or periodically measure hematocrit levels by analyzing optical properties of blood through the skin, eliminating needle punctures, reducing patient discomfort, and removing infection risks associated with repeated venipuncture procedures while maintaining continuous monitoring capability.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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 continuous, remote monitoring of hematocrit levels without the need for repeated invasive procedures, allowing for timely detection and management of conditions such as anemia.

Implementation Method 1

providing incident light to patient tissue at a first excitation wavelength to generate an emission response

Methodology Applied

Scientific EffectFluorescence: Fluorescence

Implementation Method 2

monitoring the emission response at a first wavelength and monitoring the emission response at a second wavelength

Methodology Applied

Scientific EffectPhotodetection: Photoelectric Effect

Data Source

PatentUS12262991B2System and method for non-invasive monitoring of hematocrit concentration

Publication Date: 2025.04.01 MEDTRONIC MONITORING INC

AI summary

A method of non-invasively monitoring hematocrit levels includes monitoring a first emission response to the light provided at the first excitation wavelength, wherein the first emission response is monitored at a first wavelength and monitoring a second emission response to the light provided at the first excitation wavelength, wherein the second emission response is monitored at a second wavelength. A ratiometric value is calculated based on a ratio of the first emission response to the second emission response, wherein the ratiometric value corresponds with hematocrit level of the patient.