Optical Glucose Sensing With Raman-PPG Signal Correlation
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Solution Overview
Problem
Existing non-invasive methods for measuring blood glucose levels are unreliable and require invasive blood extraction, and existing optical techniques lack a reliable method for in vivo calibration due to varying tissue conditions.
Innovation Solution
A non-invasive optical device using Raman spectroscopy and photoplethysmography (PPG) to measure blood glucose levels, employing pinned photodiodes (PPD) and correlated double sampling to enhance signal precision and accuracy, eliminating the need for calibration with standardized samples.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If invasive blood extraction is used to measure glucose levels, then measurement precision is improved, but ease of operation deteriorates due to repeated finger pricking
Solution Approach 1:
The patent replaces the mechanical invasive blood extraction system with an optical measurement system using Raman spectroscopy and photoplethysmography. The device uses light sources and photodetectors to measure glucose levels through tissue without physical penetration, thereby maintaining measurement precision while dramatically improving ease of operation by eliminating repeated finger pricking
Solution Approach 2:
The patent introduces optical signals as an intermediary between the measurement system and the glucose analyte. By using Raman scattering and photoplethysmography signals that penetrate tissue and interact with glucose molecules, the system achieves non-invasive measurement while preserving accuracy, resolving the contradiction between invasive precision and non-invasive comfort
2Measurement precision
If conventional calibration with standard solutions is used for Raman spectroscopy, then measurement precision is improved, but device complexity increases due to calibration requirements
Solution Approach 1:
The patent implements self-service calibration by using the patient's own tissue as the reference medium. The system measures optical properties in situ and uses these measurements to automatically calibrate itself, eliminating the need for external standard solutions and complex calibration procedures. This reduces device complexity while maintaining measurement precision through adaptive, real-time calibration
Solution Approach 2:
The patent changes the calibration parameter from external standard solution concentrations to in-vivo tissue optical properties. By measuring and adapting to the actual optical characteristics of the patient's tissue (scattering, absorption, path length), the system achieves automatic calibration that is simpler to implement and maintains precision without requiring complex external calibration equipment
3Ease of operation
If optical measurement techniques are used for non-invasive glucose measurement, then ease of operation is improved, but measurement precision deteriorates due to tissue variability
Solution Approach 1:
The patent performs preliminary measurement of tissue optical properties (scattering coefficients, absorption coefficients, path length) before conducting glucose measurement. This preliminary characterization of the tissue medium allows the system to compensate for tissue variability and extract accurate glucose information, thereby maintaining measurement precision while preserving the ease of non-invasive operation
Solution Approach 2:
The patent implements feedback mechanisms where the measured tissue optical properties are continuously used to adjust and optimize the glucose measurement algorithm. By feeding back the actual tissue characteristics into the measurement model, the system compensates for inter-subject and intra-subject variability, maintaining high measurement precision throughout the measurement process
4Measurement precision
If multiple optical signals are processed to improve measurement reliability, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent merges Raman spectroscopy and photoplethysmography measurements into a unified analysis framework. By combining these two optical techniques that probe different aspects of tissue-glucose interaction, the system achieves enhanced measurement precision and reliability. The merged approach leverages complementary information from both methods while using a single integrated device architecture, thereby improving precision without proportionally increasing complexity
Data Source
AI summary
An optical device for the in noninvasive determination of the concentration of glucose or another analyte in blood using a combination of Raman spectrometry and PPG. The device includes an optical detector, preferably a CMOS imager including pinned photodiodes (PPD) to collect a time-variable signal and a logic circuit arranged to determine a glucose concentration based on variations in the optical signal happening in a frequency range compatible with the cardiac rhythm.