Wearable OSA Detection via Multi-Wavelength PPG
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Solution Overview
Problem
Current methods for evaluating obstructive sleep apnea (OSA) require a nasal flow meter, which can discomfort users and degrade sleep quality, limiting their effectiveness for home use.
Innovation Solution
A wearable device using light sources of multiple wavelengths to generate photoplethysmography (PPG) signals, which are processed to determine Apnea Hypopnea Index (AHI) and Oxygen Desaturation Index (ODI) scores, eliminating the need for a nasal flow meter and enabling long-term recording.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a nasal flow meter is equipped to evaluate OSA, then measurement accuracy is improved, but user comfort deteriorates and sleep quality is degraded
Solution Approach 1:
The patent replaces the mechanical nasal flow meter with an optical detection system using PPG sensors. The PPG signals captured through the wrist are processed to derive respiratory rate and OSA indicators, eliminating the need for nasal flow meter and its associated discomfort to users.
Solution Approach 2:
The patent introduces an intermediary detection approach by measuring PPG signals through the wrist instead of directly measuring nasal airflow. This intermediary measurement path allows indirect assessment of OSA without requiring users to wear uncomfortable nasal flow meters.
2Reliability
If a nasal flow meter is used for OSA evaluation, then diagnostic capability is improved, but device complexity and user burden increase
Solution Approach 1:
The patent extracts the essential detection function from the complex nasal flow meter system and implements it through simple PPG sensors on the wrist. This extraction maintains diagnostic capability while significantly reducing device complexity and user burden.
Solution Approach 2:
The patent makes the PPG sensor system universal by using it for multiple purposes: monitoring heart rate, respiratory rate, and OSA indicators simultaneously. This multi-functionality reduces the need for separate specialized devices and lowers overall system complexity.
3Ease of operation
If home-based OSA testing is implemented, then accessibility is improved, but measurement reliability may deteriorate without professional equipment
Solution Approach 1:
The patent enables self-service OSA testing at home by providing users with a wearable device that automatically captures PPG signals and processes them to generate OSA reports. Users can perform testing independently without requiring professional equipment or expertise, while the device maintains reliable measurements through optimized signal processing.
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 wearable device accurately determines OSA level indices without disrupting sleep quality, providing a comfortable and effective method for users to assess their OSA risk at home.
Implementation Method 1
The light sensor is arranged on the inner surface and configured to output at least two photoplethysmography (PPG) signals in response to light emission of the at least one light source
Data Source
AI summary
There is provided a wearable device including at least one light source, a light sensor and a processor. The processor generates a peak interval plot according to one of at least two light detection signals detected by the light sensor when the at least one light source emits light, and generates an oxygen saturation plot according to two of the one of at least two light detection signals detected by the light sensor when the at least one emits light. The processor further determines an Apnea Hypopnea Index (AHI) score according to the peak interval plot, determines an Oxygen Desaturation Index (ODI) score according to the oxygen saturation plot and fits an obstructive sleep apnea level index corresponding to the AHI score and the ODI score.