Multispectral PPG Monitoring With Motion Artifact Correction
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Solution Overview
Problem
Current PPG systems are inaccurate due to not accounting for dynamic tissue optical properties, motion artifacts, and environmental factors, and wearable sensors fail to simultaneously measure a wide range of physiological parameters accurately.
Innovation Solution
A multispectral opto-physiological sensor system with embedded AI processing, capable of modeling tissue optical properties and physical variables, to correct for environmental and motion-induced noise, and measure parameters like heart rate, oxygen saturation, and respiration rate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional PPG systems are used, then the measurement process is simple, but the measurement precision is poor due to not accounting for dynamic tissue optical properties and motion artifacts
Solution Approach 1:
The patent segments the optical measurement into multiple wavelength channels (red, infrared, green LEDs) to separately characterize different tissue optical properties. This allows the system to model static tissue properties and dynamic blood volume changes independently, improving measurement precision while maintaining manageable system complexity through modular sensor design
Solution Approach 2:
The patent implements dynamic correction by continuously monitoring motion artifacts and adjusting the PPG signal in real-time. The system uses motion sensors to detect physical movement and applies algorithmic corrections to compensate for motion-induced optical variations, enabling accurate physiological measurement during dynamic activities
Solution Approach 3:
The patent changes the optical parameters by measuring at multiple wavelengths and using these to calculate corrected PPG values that account for tissue optical property variations. The system transforms raw optical signals into physiologically corrected parameters by adjusting for tissue characteristics and environmental factors
2Adaptability or versatility
If single-wavelength PPG measurement is used, then the device complexity is low, but the adaptability is insufficient to handle different tissue types and conditions
Solution Approach 1:
The patent creates a universal optical sensor system that can measure multiple physiological parameters (heart rate, oxygen saturation, blood volume pulse) and adapt to different tissue types, skin tones, and environmental conditions using a single multi-wavelength sensor platform. The system's ability to characterize tissue optical properties makes it universally applicable across diverse populations
Solution Approach 2:
The patent adds the wavelength dimension to optical measurement by incorporating multiple LED wavelengths (red, infrared, green). This dimensional expansion enables the system to distinguish between different tissue components and optical properties, significantly improving adaptability to various tissue types and physiological states
3Measurement precision
If motion artifacts are not corrected, then the signal processing is simpler, but the measurement precision deteriorates due to inaccurate physiological readings
Solution Approach 1:
The patent applies preliminary motion correction by continuously monitoring motion artifacts and pre-processing the PPG signal to remove motion-induced components before physiological parameter extraction. This preliminary action ensures that the subsequent physiological measurements are based on clean signals, improving accuracy without significant time delay
Solution Approach 2:
The patent implements feedback correction by using motion sensors to continuously monitor physical movement and feeding this information back into the signal processing algorithm. The system dynamically adjusts the PPG analysis based on real-time motion detection, correcting artifacts as they occur and maintaining high measurement precision during dynamic activities
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 provides accurate, real-time monitoring of multiple physiological parameters by accounting for dynamic tissue properties and motion, enhancing clinical monitoring capabilities.
Implementation Method 1
Photoplethysmography (PPG) is a non-invasive optical technique for monitoring variation in blood volume or blood flow near the surface of the skin to determine various physiological parameters. The principle uses an illumination source and a photodetector to measure changes in intensity as light is passed through or reflected from body tissue.
Implementation Method 2
Opto-physiological monitoring (beyond but including Beer-Lambert based photoplethysmography, PPG)
Data Source
AI summary
A method of monitoring a subject with an opto-physiological sensor system is described herein. The method comprises obtaining a model of the optical properties of at least one body tissue type to be monitored, wherein the model of the optical properties comprises a definition of static (DC) and dynamic (AC) components of transmitted optical power and a definition of a source-detector separation related to a normalised path length for an illumination source of the opto-physiological sensor: obtaining an indication of at least one physiological property of the subject from a wearable device worn by the subject: obtaining an indication of at least one physical variable from the wearable device worn by the subject; determining, using the opto-physiological model, how the at least one physical variable affects the at least one physiological property; and determining a corrected value for the physiological property based on the determination of how the at least one physical variable affects the at least one physiological property.