Adaptive PPG Monitoring for Motion Artifacts and Power Control
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Solution Overview
Problem
Conventional photoplethysmography devices face challenges in maintaining consistent skin contact during physical activity, leading to reduced signal quality due to motion artifacts and high power consumption, especially when used in wearable forms like earbuds, which can be uncomfortable and inefficient in power management.
Innovation Solution
A monitoring device with a processor that adjusts signal analysis frequency and sensor interrogation power based on detected changes in activity, using optical sensors with adjustable algorithms and power settings to optimize data collection during varying activity levels, and incorporating motion sensors to enhance skin coupling and reduce power usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the magnitude of light energy reaching the body is increased to improve signal quality, then measurement precision is improved, but use of energy increases
Solution Approach 1:
The patent applies dynamics by making the light energy magnitude adjustable rather than fixed. The system dynamically adapts the interrogation power based on detected activity levels, using higher power during low activity for quality measurements and reducing power during high activity when motion artifacts dominate anyway.
Solution Approach 2:
The patent changes the parameter of light energy magnitude based on activity detection. By monitoring activity levels and adjusting the light energy parameter accordingly, the system optimizes the balance between signal quality and power consumption, using higher energy only when conditions favor accurate measurement.
2Measurement precision
If signal analysis frequency is increased to improve measurement accuracy during exercise, then measurement precision is improved, but use of energy increases
Solution Approach 1:
The system dynamically adjusts signal analysis frequency based on detected activity levels. During exercise, the frequency is increased to capture rapid physiological changes accurately. During rest periods, the frequency is reduced to conserve battery power, as high-frequency sampling is unnecessary when physiological parameters are stable.
Solution Approach 2:
The patent changes the signal analysis frequency parameter in response to activity detection. This adaptive approach ensures high measurement accuracy is maintained only when needed (during exercise), while power consumption is minimized during low-activity periods when physiological changes are slower.
3Reliability
If elastomeric features are added to earbuds to improve retention during exercise, then reliability is improved, but optical skin coupling is reduced
Solution Approach 1:
The patent segments the earbud into distinct functional zones: elastomeric features are placed in regions dedicated to retention and stability, while optical sensors are positioned in zones optimized for skin contact and light coupling. This spatial segmentation allows each feature to perform its function without interfering with the other.
Solution Approach 2:
Different regions of the earbud are given different properties: elastomeric materials are applied locally to retention features rather than the entire device, and optical coupling surfaces are prepared with specific local characteristics (smoothness, contact pressure) optimized for photoplethysmography in the regions where sensors are placed.
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 solution improves the accuracy and reliability of physiological data collection by adapting to different activity levels, reducing motion artifacts, and conserving power, allowing for more precise monitoring during exercise while maintaining functionality during periods of inactivity.
Implementation Method 1
Photoplethysmography (PPG) is based upon shining light into the human body and measuring how the scattered light intensity changes with each pulse of blood flow
Implementation Method 2
The sensor module includes at least one optical emitter
Data Source
AI summary
A monitoring device configured to be attached to a body of a subject includes a sensor configured to detect and/or measure physiological information from the subject, and a processor coupled to the sensor that is configured to receive and analyze signals produced by the sensor. The processor is configured to change signal analysis frequency and/or sensor interrogation power in response to detecting a change in subject activity, a change in subject stress level, a change in environmental conditions, a change in time, and/or a change in location of the subject.