Wearable Respiration Rate Monitoring via PPG Signal Processing
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Solution Overview
Problem
Current wearable technologies face challenges in accurately and continuously monitoring respiration rate using photoplethysmographic (PPG) signals due to complex signal processing requirements that exceed the computational capabilities of small, unobtrusive devices.
Innovation Solution
A method and system for non-invasive respiration rate monitoring using a wearable device that transforms optical signals into indicators of respiration rate by detecting peaks and valleys, determining time differences, and estimating respiration rate from these measurements, employing a low-power microprocessor and simplified computational methods.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If specialized equipment like end-tidal CO2 monitors, EKG-based trans-thoracic impedance systems, nasal thermistors, or abdominal and chest bands are used for continuous respiration rate measurement, then measurement precision and reliability are improved, but device complexity and intrusiveness increase
Solution Approach 1:
The patent applies multi-functionality by using a PPG sensor originally designed for blood oxygen saturation measurement to also extract respiration rate information. The same optical sensor and signal processing system serve dual purposes: monitoring SpO2 and deriving respiratory parameters from the PPG signal's respiratory component, thereby eliminating the need for separate specialized respiration monitoring equipment.
Solution Approach 2:
The patent combines respiration rate measurement functionality with the existing PPG blood oxygen monitoring system. By merging the respiration detection capability into the PPG signal processing pipeline, the system integrates multiple monitoring functions into a single unified device, reducing overall system complexity while maintaining measurement precision.
2Measurement precision
If advanced signal processing capabilities are implemented to extract respiration information from PPG signals, then measurement precision is improved, but computational power requirements and device complexity increase
Solution Approach 1:
The patent extracts only the essential respiratory component from the PPG signal by isolating the respiratory modulation envelope. Instead of implementing full advanced signal processing, the system selectively extracts the respiratory frequency information from the PPG waveform's amplitude modulation, removing unnecessary computational complexity while preserving measurement accuracy.
Solution Approach 2:
The patent applies preliminary filtering and preprocessing to the PPG signal to prepare it for respiration rate extraction. By performing initial signal conditioning, noise reduction, and respiratory component isolation before the main measurement algorithm, the system simplifies subsequent processing steps and reduces the computational burden on the wearable device.
3Ease of operation
If a wearable device is made smaller and more unobtrusive, then ease of operation and patient comfort are improved, but computational processing power is reduced
Solution Approach 1:
The patent implements partial action by performing only the essential computational steps needed for respiration rate measurement from PPG signals. Instead of running comprehensive advanced signal processing algorithms, the device executes a streamlined version that extracts the critical respiratory envelope information, sufficient for accurate measurement while minimizing computational requirements.
Solution Approach 2:
The patent replaces complex mechanical or electronic respiratory sensing mechanisms with optical PPG-based detection. By substituting direct respiratory measurement hardware (which would require more processing power) with optical detection of respiratory-induced PPG modulations, the system achieves comparable measurement capability with reduced computational demands suitable for small wearable devices.
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 continuous, non-intrusive monitoring of respiration rate with a wearable device, allowing for mobile and remote reading of data, including internet connectivity, using a low-power microprocessor to process PPG signals effectively.
Implementation Method 1
Photoplethysmography or photoplethysmographic (PPG) systems have been used in an attempt to measure various blood flow characteristics including, but not limited to, the blood-oxygen saturation of hemoglobin in arterial blood
Implementation Method 2
In generating the PPG signal, the wavelength A of a light source on one side is placed in a protrusion, for example a finger and a photo-detector or PPG sensor may be placed to other side of the source to capture the transmitted light
Data Source
AI summary
There is disclosed a respiration rate monitoring system and method using a non-invasive device and method of monitoring it nearly continuously. One aspect includes receiving a series of signal data points from an optical sensor, detecting a series of peaks or valleys for the filtered signal data points, determining the time difference between individual peaks or valleys of the series of peaks or valleys to produce a series of time difference values, detecting peaks or valleys for the series of time difference values, determining widths between the peaks or valleys of the series of time difference values, and estimating a respiration rate from the widths between the peaks or valleys of the series of time difference values, and converting the estimation of a respiration rate to an indicator indicative of a respiration rate.