Fluorescence Concentrator for Optical Absorption Spectroscopy

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Solution Overview

Problem

Optical absorption spectroscopy in living tissue, such as skin, is hindered by strong light scattering, making it difficult to quantify weakly absorbing analytes like glucose due to the indeterminacy of light paths and resulting in unreliable results.

Innovation Solution

A subcutaneously implanted fluorescence concentrator is used, which converts incident light into fluorescent light of longer wavelengths, concentrating and directing it towards the skin surface for detection, allowing for reliable quantification of analytes independent of their absorption strength and minimizing the impact of light scattering.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If light is propagated through tissue for absorption spectroscopy, then analyte quantification is possible, but light scattering causes indeterminacy of light paths and unreliable results

Engineering Contradiction:
Improveanalyte quantification accuracyVSAvoidmeasurement reliability
Core Design Contradiction:
Measurement precisionVSReliability

Solution Approach 1:

The patent introduces a fluorescent layer as an intermediary substance applied to the skin surface. This fluorescent layer absorbs incident light and re-emits it as fluorescent light, serving as a mediator between the external light source and the tissue. The fluorescent light then interacts with the tissue and analytes, allowing absorption spectroscopy to be performed on the fluorescent light that has passed through the tissue, thereby enabling reliable analyte quantification despite light scattering effects.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Measurement precision

If weakly absorbing particles are measured in small concentrations, then analyte detection is required, but strong light scattering makes quantification difficult or impossible

Engineering Contradiction:
Improveweakly absorbing analyte detectionVSAvoidlight scattering interference
Core Design Contradiction:
Measurement precisionVSObject-affected harmful factors

Solution Approach 1:

The fluorescent layer acts as an intermediary that converts incident light into fluorescent light with specific wavelengths. This fluorescent light then serves as the probing light for absorption spectroscopy, allowing weakly absorbing analytes to be detected against the background of tissue scattering. The fluorescent emission provides a controlled light source at the tissue interface, improving the signal-to-noise ratio for detecting weakly absorbing substances.

Inventive Principle:
Principle #24Intermediary (Mediator)

3Ease of operation

If light source is placed subcutaneously for direct tissue illumination, then absorption spectroscopy can be performed, but no power supply is available for the implant

Engineering Contradiction:
Improvesubcutaneous light source operationVSAvoidpower supply requirement
Core Design Contradiction:
Ease of operationVSUse of energy by moving object

Solution Approach 1:

The system uses self-service by employing the incident light from the external light source as the energy source. The fluorescent layer on the skin surface automatically converts this incident light into fluorescent light without requiring any power supply. This eliminates the need for batteries or other power sources in the subcutaneous device, as the system harvests its own operating energy from the external light that would otherwise be wasted.

Inventive Principle:
Principle #25Self-service

4Productivity

If fluorescent dye is applied to transparent plate for light concentration, then diffuse light can be concentrated, but light trapping via total reflection must be optimized

Engineering Contradiction:
Improvelight concentration efficiencyVSAvoidlight trapping loss
Core Design Contradiction:
ProductivityVSLoss of energy

Solution Approach 1:

The patent employs a transparent plate with specific geometric dimensions and optical properties to concentrate fluorescent light. The plate structure utilizes total internal reflection at its interfaces to trap and guide the fluorescent light, converting diffuse emission into a concentrated beam. The plate's geometry and refractive index are optimized to maximize light concentration while minimizing losses through controlled coupling of light into and out of the plate structure.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

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 precise and reliable absorption spectroscopy by collecting and concentrating diffuse light, distinguishing between fluorescent light and tissue-emitted light, and allows for repeated measurements without a power supply, improving the accuracy and reliability of analyte quantification.

Implementation Method 1

has a fluorescent layer 112, wherein the fluorescent layer 112 is designed to absorb a light 13 emitted onto the skin surface 10 and to convert the absorbed light into a fluorescent light

Methodology Applied
Scientific EffectFluorescence: Fluorescence

Implementation Method 2

Since the radiation takes place within the material, a large part of the light remains trapped in the sheet via total reflection, like in a light guide

Methodology Applied
Scientific EffectTotal internal reflection: Total Internal Reflection

Data Source

PatentEP2759255B1Assembly for performing optical absorption spectroscopy and devices
Publication Date: 2017.08.16 ROBERT BOSCH GMBH
  • EP2759255B1 patent drawingFigure 1~2
  • EP2759255B1 patent drawingFigure 3~4
  • EP2759255B1 patent drawingFigure 5~6

AI summary

The device (11) has a fluorescent layer (112) which is arranged to absorb light (13) radiated from a skin surface (10), and to convert the absorbed light into a fluorescent light (14). A fluorescent light radiating portion (113) is provided to receive the fluorescence light, and radiate received light in a direction of the skin surface. The fluorescent layer is formed on a substrate (111) formed of high-refractive index material. An independent claim is included for the light detecting device.