CAP Detection Device Using Pulse Wave Baseline Analysis
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Solution Overview
Problem
Current sleep stage monitoring systems, relying on electroencephalograms or body movements, fail to accurately reflect sleep subjectivity, as they do not effectively correlate with sleep satisfaction, and thus cannot adequately assess sleep quality based on cyclic alternative patterns (CAPs).
Innovation Solution
A CAP detection device that acquires pulse wave data, derives a baseline and envelope, identifies local maximum and minimum points, and evaluates candidate points using differences between these points to detect CAPs, providing a sleep index that better represents sleep subjectivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If sleep stage monitoring is performed using electroencephalograms, then sleep stages can be determined, but the correlation with sleep subjectivity is not high
Solution Approach 1:
The patent replaces the electroencephalogram-based detection system with a pulse wave-based detection system. By substituting the mechanical/electrical measurement method (EEG) with an optical/photoelectric method (pulse wave detection using light absorption changes), the system achieves better correlation with sleep subjectivity while maintaining sleep stage determination capability
Solution Approach 2:
The patent changes the measurement parameter from brain wave electrical signals to pulse wave optical signals. By detecting changes in light absorption caused by blood volume variations in the pulse wave, the system extracts CAP information that correlates more strongly with sleep subjectivity, thus resolving the contradiction between measurement precision and information loss
2Ease of operation
If body movements and pulse waves are used for sleep monitoring, then easier data acquisition is achieved, but sleep quality assessment based on CAP is insufficient
Solution Approach 1:
The patent extracts the CAP signal from the pulse wave data by identifying specific waveform characteristics (inflection points, peaks, and troughs). By isolating and analyzing the CAP component separately from other pulse wave features, the system achieves accurate sleep quality assessment while maintaining the ease of pulse wave data acquisition
Solution Approach 2:
The patent uses pulse wave inflection points as an intermediary to detect CAP. The inflection points serve as a mediator that translates the complex pulse wave signal into detectable CAP characteristics, enabling accurate sleep quality assessment while keeping the measurement method simple and easy to implement
Data Source
AI summary
A CAP detection device configured to acquire pulse wave data of a subject, derive a baseline of the data and an envelope of the baseline, identify a local maximum point of the envelope and determine, as CAP candidate points, a first local maximum point of the baseline before the local maximum point of the envelope and a second local maximum point of the baseline after the local maximum point, and identify, for each CAP candidate point, a third local maximum point of the baseline before the CAP candidate point and a local minimum point of the baseline between the CAP candidate point and the third local maximum point and detect the CAP candidate point as a CAP based on an evaluation value obtained from a difference between the CAP candidate point and the third local maximum point and a difference between the CAP candidate point and the local minimum point.