Multi-Wavelength Light Sensing for Hemoglobin and Pigmentation Separation
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Solution Overview
Problem
Existing non-invasive physiological monitoring technologies face challenges in accurately determining hemoglobin disorders due to interference from skin pigmentation and water absorption, leading to noise and inaccurate measurements.
Innovation Solution
A light sensing device that emits and detects light at characteristic wavelengths, including UV and IR, using parallel photodetectors with different responsivities to measure both transmission and reflectance, and employs different optical path lengths to improve signal quality and reduce noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If UV or near-UV wavelengths are used to measure hemoglobin absorption, then hemoglobin detection sensitivity is improved, but noise from skin pigmentation increases
Solution Approach 1:
The patent segments the measurement into multiple wavelength ranges (UV, visible, IR) and multiple detection modes (transmission and reflectance). By dividing the spectral range and using parallel photodetectors for different wavelengths, the system can separately characterize hemoglobin absorption at characteristic wavelengths while using other wavelengths to compensate for pigmentation effects, thus resolving the contradiction between sensitivity and noise.
Solution Approach 2:
The patent introduces water absorption at infrared wavelengths as an intermediary to differentiate between water and hemoglobin absorption. By measuring water absorption at IR wavelengths where hemoglobin absorption is minimal, the system can compensate for pigmentation effects and isolate true hemoglobin signal, reducing noise while maintaining detection sensitivity.
2Measurement precision
If multiple wavelengths are measured to differentiate water and hemoglobin absorption, then measurement accuracy is improved, but device complexity increases
Solution Approach 1:
The patent merges transmission and reflectance detection modes into a single integrated light sensing device with parallel photodetectors. Multiple photodetectors with different responsivities are placed in parallel in the same circuit, allowing simultaneous measurement of multiple wavelengths. This combining approach reduces device complexity compared to separate transmission and reflectance devices while maintaining the ability to differentiate water and hemoglobin absorption.
Solution Approach 2:
The light sensing device is designed with multi-functionality to perform both transmission and reflectance measurements using the same device structure. The parallel photodetector configuration allows a single device to measure multiple wavelengths and modes simultaneously, providing universal functionality for characterizing both water and hemoglobin absorption without requiring multiple separate devices.
3Object-affected harmful factors
If reflective position photodetectors are used to characterize superficial tissue, then pigmentation noise is reduced, but optical path length decreases
Solution Approach 1:
The patent segments the optical path into two distinct components: a short reflective path for characterizing superficial tissue and pigmentation effects, and a long transmission path for measuring total hemoglobin. By using photodetectors at different positions with different optical path lengths, the system can separately measure and compensate for pigmentation noise while maintaining accurate hemoglobin measurement through the longer transmission path.
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
The system effectively determines total hemoglobin levels and identifies hemoglobin disorders by minimizing the impact of skin pigmentation and water absorption, providing accurate physiological parameters.
Implementation Method 1
A light sensing device may emit various wavelengths of light that are collected by photodetectors of the light sensing device
Implementation Method 2
The signals from such wavelengths may be used to compare water absorption to hemoglobin absorption for a total hemoglobin measurement
Implementation Method 3
Shorter wavelengths present a higher noise based on pigmentation because of the absorption spectrum of melanin
Implementation Method 4
water may dominate the absorption at these longer wavelengths, so the IR wavelengths may be used to compare the absorption of water versus hemoglobin
Data Source
AI summary
A light sensing device includes a first light source configured to emit light within a first wavelength range, a second light source configured to emit light within a second wavelength range, detector circuitry, a first photodetector in the detector circuitry configured to detect the light within the first wavelength range, and a second photodetector in the detector circuitry configured to detect the light within the second wavelength range. The first photodetector and the second photodetector are in parallel in the detector circuitry such that the detector circuitry sums electrical signals outputted by the first photodetector and the second photodetector.