Optical PPG Monitoring With Adaptive Power and Signal Confidence
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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 monitoring physiological data accurately.
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 light wavelengths to enhance data accuracy and conserve power, while also considering environmental and stress-level changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional photoplethysmography devices use a spring to clip the sensor onto the body, then the sensor can maintain contact with the skin, but the device has large mass and cannot maintain consistent skin contact during high acceleration activities
Solution Approach 1:
The patent transitions from a static spring-based clipping mechanism to a dynamic adhesive bonding system that can adapt to motion. The adhesive layer allows the sensor to maintain consistent skin contact during high acceleration activities without relying on mechanical springs that add mass and fail under dynamic conditions.
Solution Approach 2:
The patent replaces the mechanical spring-based retention system with an adhesive bonding system. This substitution eliminates the need for heavy mechanical components while achieving more reliable skin contact consistency during physical activity, directly addressing the contradiction between reliability and weight.
2Measurement precision
If optical sensors continuously operate at high power to capture physiological data during physical activity, then measurement accuracy is improved, but power consumption increases significantly
Solution Approach 1:
The patent implements dynamic adjustment of optical sensor operation modes based on detected activity levels. During high-intensity physical activity, the sensor operates at higher power for accurate measurements, while during low-intensity periods, it reduces power consumption. This dynamic adaptation resolves the contradiction between maintaining measurement precision and managing power usage.
Solution Approach 2:
The patent changes operational parameters of the optical sensor based on activity detection. By adjusting sampling rates, light emission intensity, and processing frequency according to the user's physical state, the system maintains measurement accuracy when needed while minimizing power consumption during less demanding periods.
3Reliability
If earbuds incorporate elastomeric surfaces and springs to dampen acceleration during vigorous activity, then retention in the ear is improved, but optical skin coupling requirements are not adequately addressed
Solution Approach 1:
The patent separates the retention function from the optical coupling function. The elastomeric surface and springs handle retention and mechanical damping, while a dedicated adhesive layer handles optical skin coupling. This segmentation allows each component to optimize its specific function without compromising the other.
Solution Approach 2:
The patent applies different material properties to different regions of the earbud. The outer surface uses elastomeric materials for retention, while the sensor contact area uses specialized adhesive materials optimized for optical coupling. This local differentiation resolves the contradiction by allowing each region to excel at its specific function.
4Measurement precision
If signal analysis frequency and sensor interrogation power are maintained at high levels continuously, then physiological data accuracy is improved, but battery life is reduced
Solution Approach 1:
The patent implements periodic adjustment of signal analysis frequency and sensor interrogation power based on detected activity patterns. Instead of continuous high-level operation, the system dynamically scales these parameters up during active periods and down during rest periods, maintaining accuracy when needed while extending battery life through periodic low-power states.
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 during physical activity by adapting signal processing to activity levels, reduces power consumption, and ensures comfortable wear, thereby extending battery life and enhancing user experience.
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
A sensor module includes at least one optical emitter and at least one optical detector
Data Source
AI summary
A monitoring device configured to be attached to a subject includes a photoplethysmography (PPG) sensor configured to measure physiological information from the subject, a blood flow stimulator, and a processor configured to process signals from the PPG sensor to determine a confidence score of the signals. In response to a signal-to-noise level determination, the processor is configured to instruct the blood flow stimulator to increase blood perfusion at a location where the PPG sensor is attached to the subject. The confidence score is an indication of how strongly the signals can be trusted.