PPG Sensor Heart Rate Signal Segmentation for Wearable Noise
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Solution Overview
Problem
Current cardiovascular monitoring devices using photoplethysmography (PPG) sensors face challenges with noise and unreliable measurements, particularly in wearable devices, due to movement-based noise contamination, which limits their use in clinical monitoring and daily life applications.
Innovation Solution
A device and method that detect movement events and extract time segments from heart rate signals contaminated with noise, combining these segments to compute an aggregated heart rate response signal, which is then used to determine cardiovascular health information, such as 'HeartAge', allowing for unobtrusive monitoring during rest or sleep.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If PPG sensors are used for cardiovascular monitoring in wearable devices, then convenience and continuous monitoring capability are improved, but measurement reliability deteriorates due to movement-based noise contamination
Solution Approach 1:
The patent segments the heart rate signal into multiple intervals based on detected movement events. By dividing the continuous signal into discrete segments associated with specific movements, the system can analyze cardiovascular response to individual events while filtering out noise from periods without meaningful events, thus maintaining reliability in wearable conditions.
Solution Approach 2:
The patent converts movement-based noise, traditionally considered harmful, into useful information. By detecting movement events and using them as triggers to extract meaningful cardiovascular response data, the system transforms the previously problematic movement artifacts into valuable markers for analyzing heart rate variability and cardiovascular health indicators.
2Reliability
If time segments contaminated by movement noise are ignored or filtered out, then measurement reliability is improved, but loss of information increases due to discarding potentially valuable data
Solution Approach 1:
Instead of discarding time segments with movement artifacts, the patent detects movement events within these segments and extracts cardiovascular response information triggered by them. This converts previously discarded noisy data into valuable information about cardiovascular reactivity to movement stimuli.
Solution Approach 2:
The patent performs preliminary detection of movement events before extracting heart rate signal segments. By identifying movement events in advance and using them as selection criteria for extracting relevant time segments, the system ensures that only meaningful cardiovascular response data associated with actual movements are analyzed, preventing loss of valuable information while maintaining reliability.
3Measurement precision
If multiple sensors are placed at specific positions for ECG monitoring, then measurement precision is improved, but device complexity increases making it inefficient as wearable
Solution Approach 1:
The patent enables a single PPG sensor to perform multiple functions: it detects heart rate, detects movement events through pulse signal variations, and extracts cardiovascular response information to movements. This multi-functionality replaces the need for multiple specialized sensors required by ECG, reducing device complexity while maintaining monitoring precision.
Solution Approach 2:
The PPG sensor system performs self-service by using its own heartbeat signal to detect movement events. The pulse oximeter naturally captures both cardiovascular information and movement artifacts, eliminating the need for separate movement sensors or multiple ECG electrodes, thus simplifying the device while maintaining measurement precision.
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
Enables accurate and continuous monitoring of cardiovascular vitality, potentially detecting early signs of cardiovascular issues, and providing a powerful indicator of cardiovascular adaptability, facilitating early risk detection and improving healthcare outcomes.
Implementation Method 1
Photoplethysmography (PPG) sensors solve this problem by measuring heart rate (HR) and heart rate variability (HRV) with pulse oximeters that emit light on the skin and measure the intensity of the reflection. This intensity is dependent on blood flow beneath the skin that is regulated by the cardiac cycle.
Implementation Method 2
In addition to that, remote PPG has been found to be able to detect vital signs, such as HR, respiration rate, SpO2, from a camera signal of a skin portion of the subject.
Data Source
AI summary
Fluctuations in heart rate above 0.03 Hz reflect autonomic modulation of sinoatrial node activity. To assess the dynamics of autonomic nervous activity during and immediately after exercise, we determined the power spectrum of heart rate and respiratory fluctuations in 43 normal subjects without known cardiac disease, 8 patients with severe congestive heart failure, and 6 patients status-post cardiac transplantation before, during, and after graded-work load exercise on a cycle ergometer. Before exercise, heart rate fluctuations (spectral power) at both high (0.15-0.80 Hz) and low (0.03-0.15 Hz) frequencies were significantly higher in normal subjects than in either heart failure or transplant patients but were not different between the two groups with heart disease. During exercise, heart rate power at all frequencies rapidly and progressively decreased in normal subjects, until at peak exercise it was not different from the other two groups. During recovery, heart rate power increased in normal subjects but remained significantly below base line. The findings demonstrate a marked reduction of autonomic modulation of heart rate in patients with heart failure and after cardiac transplant and support a progressive withdrawal of vagal activity during exercise with a gradual increase during recovery in normal subjects.