Bio-signal Processor Stability-Based Wave Extraction
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Solution Overview
Problem
Current bio-signal monitoring technologies face challenges in accurately estimating bio-information, particularly blood pressure, due to instability in local minimum points of second-order differential signals, leading to non-ideal waveform shapes caused by noise and non-ideal contact conditions.
Innovation Solution
The apparatus and method involve a sensor to obtain bio-signals and a processor that determines the stability of local minimum points in second-order differential signals, extracting a progressive wave component based on stable or unstable conditions, using either the first local minimum point or maximum amplitude points to estimate bio-information such as blood pressure, vascular age, and arterial stiffness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the first local minimum point of the second-order differential signal is used to extract the progressive wave component, then the extraction method is simple, but the extraction accuracy deteriorates when the local minimum point is unstable due to noise or non-ideal contact conditions
Solution Approach 1:
The patent changes the parameter used for progressive wave component extraction based on the stability of the local minimum point. When the local minimum point is unstable (detected through inflection point analysis), the system switches from using the local minimum point to using the maximum amplitude point in the systolic portion, thereby maintaining extraction accuracy under varying signal conditions
Solution Approach 2:
The system implements feedback by continuously monitoring the stability of the local minimum point through inflection point detection in the second-order differential signal. Based on this feedback, the extraction method is dynamically adjusted to ensure accurate progressive wave component extraction regardless of signal quality
2Measurement precision
If the maximum amplitude point in the systolic portion is used to extract the progressive wave component, then the extraction accuracy is maintained under unstable conditions, but the extraction method becomes more complex
Solution Approach 1:
The patent applies dynamics by making the extraction method adaptable rather than fixed. The system dynamically selects between two extraction approaches (local minimum point method or maximum amplitude point method) based on the real-time stability assessment of the differential signal, optimizing the balance between simplicity and accuracy
3Loss of time
If traditional PPG signal analysis is performed without stability assessment, then the processing is faster, but the bio-information estimation reliability deteriorates due to noise and non-ideal contact conditions
Solution Approach 1:
The patent performs preliminary stability assessment of the local minimum point before proceeding with progressive wave component extraction. By detecting inflection points in advance and determining stability, the system prepares the appropriate extraction method beforehand, ensuring reliable bio-information estimation without excessive processing delay
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
This approach allows for stable extraction of progressive wave components, even in non-ideal conditions, enabling accurate estimation of bio-information with reduced noise and variability, improving the reliability of bio-signal monitoring.
Implementation Method 1
a pulse wave sensor including a light source configured to emit light onto the object, and a detector configured to detect light reflected by or scattered from the object
Implementation Method 2
a pulse wave sensor including a light source configured to emit light onto the object, and a detector configured to detect light reflected by or scattered from the object
Data Source
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AI summary
An apparatus for estimating bio-information may include a sensor configured to obtain a bio-signal from an object, and a processor configured to obtain a second-order differential signal of the bio-signal, and extract a progressive wave component from the bio-signal using, based on a first local minimum point of the second-order differential signal being stable, the first local minimum point of the second-order differential signal, or extract the progressive wave component from the bio-signal using, based on the first local minimum point of the second-order differential signal being unstable, a maximum amplitude point in a systolic portion of the bio-signal.