Water Concentration Measurement in Light-Diffusing Materials

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Solution Overview

Problem

Existing methods for measuring water concentration in light-scattering materials, such as human skin, are limited by their inability to provide absolute and quantitative values due to interfering factors like scattering coefficients and penetration depth variations, and require cumbersome calibration processes.

Innovation Solution

A method using spatially resolved spectroscopy coupled with experimental calibration or physical modeling to measure water concentration by tracing reduced diffusion and absorption coefficients, employing light sources and sensors with specific wavelengths and configurations to isolate water absorption signals, and numerical simulations to determine water concentration without the need for a spectrometer.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If infrared spectrophotometry is used to measure water concentration, then direct optical analysis is achieved, but measurement accuracy is compromised by interfering factors such as scattering coefficients and penetration depth variations

Engineering Contradiction:
Improvewater concentration measurement accuracyVSAvoidscattering coefficients and penetration depth variations
Core Design Contradiction:
Measurement precisionVSObject-affected harmful factors

Solution Approach 1:

The measurement system is segmented into multiple independent light sources emitting at different wavelengths (some at water absorption peaks, others at non-absorption wavelengths) and multiple sensors positioned at different distances. This segmentation allows separate measurement of water absorption and scattering effects, enabling accurate water concentration determination despite the presence of scattering and penetration depth variations.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent introduces intermediary measurements at wavelengths far from water absorption peaks to characterize scattering effects and penetration depth. These intermediary measurements serve as compensatory factors that are then used to correct the water absorption measurements, eliminating the harmful influence of scattering and geometric variations on water concentration accuracy.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Measurement precision

If calibration processes are used to determine water concentration, then quantitative values can be obtained, but the process becomes cumbersome and complex

Engineering Contradiction:
Improvequantitative water concentration valuesVSAvoidcalibration process complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The measurement system performs self-calibration by automatically determining scattering coefficients and penetration depth parameters from the same measurements taken at non-absorption wavelengths. This self-service approach eliminates the need for external calibration standards and complex calibration procedures, while still enabling accurate quantitative water concentration measurements.

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The patent changes the measurement parameters by simultaneously measuring at multiple wavelengths (both at and far from water absorption peaks) and at multiple source-sensor distances. This parameter expansion allows the system to self-determine compensatory factors and perform calibration-free quantitative measurements, reducing procedural complexity while maintaining accuracy.

Inventive Principle:
Principle #35Parameter changes

3Measurement precision

If multiple light sources and sensors at different wavelengths and positions are used, then water absorption and scattering effects can be separated, but device complexity increases

Engineering Contradiction:
Improveseparation of absorption and scattering effectsVSAvoidnumber of light sources and sensors
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent designs a universal measurement system where multiple light sources and sensors serve multiple functions: some sources/sensors measure water absorption at peak wavelengths, others measure scattering effects at non-absorption wavelengths, and together they enable simultaneous determination of water concentration, scattering coefficient, and penetration depth. This multi-functionality justifies the increased component count by providing comprehensive characterization capability.

Inventive Principle:
Principle #6Universality (Multi-functionality)

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 absolute and non-relative measurement of water concentration in light-scattering materials, improving accuracy and reducing calibration complexity, allowing for precise characterization of water content in various materials including skin, hair, paper, and plants.

Implementation Method 1

The evaluation of the water concentration in the sample is thus obtained by comparing the power received at a wavelength close to an absorption band of water molecules with that received at a wavelength far from the bands absorption of water molecules

Methodology Applied
Scientific EffectLight absorption: Absorption (EM radiation)

Implementation Method 2

measuring the concentration of water contained in a light-scattering material such as human skin, plants, papers, plasters, etc.

Methodology Applied
Scientific EffectLight scattering: Scattering

Implementation Method 3

detecting electromagnetic radiation diffused and reflected by the tissue

Methodology Applied
Scientific EffectLight detection: Photoelectric Effect

Data Source

PatentEP3449239B1Method and apparatus for measuring the water concentration in a light-diffusing material
Publication Date: 2023.08.16 CONNECTED PHYSICS
  • EP3449239B1 patent drawingFigure 1
  • EP3449239B1 patent drawingFigure 2
  • EP3449239B1 patent drawingFigure 3~4

AI summary

The invention relates to a method for measuring the water concentration in a light-diffusing material, which includes the following steps: an emission by N light sources (2, 3) SLi of beams with Lambda wavelengths; an acquisition by M sensors (4) Pj, sensitive in at least one portion of said Lambda wavelengths; wherein M+N>3. The invention also includes the steps of: calculating a first piece of information ldif representing the diffusion, and a second piece of information labs representing the absorption, as a function of said signals Sj and a piece of digital information representing the diffusing material as well as said sources SLi and said sensors Pj; calculating said water concentration in the sample as a function of said second piece of information labs.