Pulse Wave Sensor Cough Detection via Amplitude Analysis
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Solution Overview
Problem
Existing methods for detecting vital functions such as cough and yawn are complex, inaccurate, and difficult to implement in private homes or vehicles, due to noise interference, motion artifacts, and the need for specialized equipment.
Innovation Solution
A pulse wave sensor-based system that uses amplitude and waveform analysis to detect cough and yawn by identifying specific patterns in pulse wave signals, including diastolic and systolic phases, and respiration waveforms, with multiple criteria for determining the occurrence of these events to enhance accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If spiro-breathing flow meter, thyroid signals, or catheter vibration methods are used to detect cough, then measurement accuracy is improved, but device complexity and ease of operation deteriorate
Solution Approach 1:
The patent replaces complex mechanical measurement devices (spirometers, catheters) with a simple optical sensor that detects pulse wave changes. The pulse wave sensor uses light absorption changes in blood vessels to detect respiratory movements and cough events, eliminating the need for complex mechanical systems while maintaining detection capability.
Solution Approach 2:
The patent uses pulse wave signals as an intermediary to indirectly detect cough events. Instead of directly measuring respiratory flow or catheter vibration, the system detects changes in pulse wave amplitude and morphology that occur during coughing, providing an indirect but accurate measurement method.
2Device complexity
If voice signals detected by microphone are used to detect cough, then device complexity is reduced, but measurement precision deteriorates due to noise interference
Solution Approach 1:
The patent replaces acoustic detection (microphone-based voice signal analysis) with optical detection using pulse wave sensors. This substitution eliminates noise interference problems associated with acoustic methods while maintaining simple device architecture, as the optical sensor directly measures physiological changes without being affected by environmental noise.
Solution Approach 2:
The patent converts the natural physiological response to coughing (changes in blood flow and pulse wave characteristics) into a detectable signal. Instead of trying to filter out noise from voice signals, the system uses the body's own physiological changes during coughing as the detection mechanism, turning a potentially harmful effect (blood pressure changes) into a useful diagnostic signal.
3Device complexity
If camera image or bed load variation is used to detect cough, then device complexity is reduced, but measurement precision deteriorates due to motion artifacts and positioning limitations
Solution Approach 1:
The patent replaces visual/mechanical detection methods (camera imaging, bed load sensors) with optical pulse wave detection. This substitution eliminates motion artifact problems and positioning constraints, as the pulse wave sensor can be placed on the finger or wrist where it is less affected by body movements during coughing.
Solution Approach 2:
The patent uses pulse wave signals as an intermediary that is less susceptible to motion artifacts compared to camera images or bed load measurements. The pulse wave detection at peripheral sites (finger, wrist) provides a more stable signal during body movement, enabling accurate cough detection without strict positioning requirements.
4Measurement precision
If pulse wave amplitude analysis is used to detect motion artifact, then measurement precision of vital function detection is improved, but device complexity increases due to multiple detection criteria
Solution Approach 1:
The patent segments the pulse wave signal into distinct phases (systolic upstroke, peak, diastolic decline) and analyzes specific characteristics of each phase. By dividing the complex pulse wave into manageable segments with specific diagnostic features, the system can accurately detect cough events and motion artifacts through targeted analysis of individual waveform portions rather than attempting to analyze the entire signal at once.
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 detection of cough and yawn in a simpler and more reliable manner, allowing for quantitative evaluation of respiratory conditions and symptom diagnosis, while avoiding motion artifacts and equipment limitations.
Implementation Method 1
a pulse wave sensor 1, a control unit 3 and a mounting device 15 for mounting the pulse wave sensor unit on a body part
Implementation Method 2
the amplitude on p-diastole side corresponding to the succeeding diastolic phase of the heart has exceeded a predetermined level
Implementation Method 3
an optical device for measuring a pulse wave
Data Source
AI summary
An apparatus for detecting vital functions has a pulse wave sensor attachable to a body and a control unit. The control unit checks if amplitude of pulse wave signals produced from the pulse wave sensor varies. The control unit further checks if a large change in the amplitude during a systolic phase of a pulse wave corresponding to the systolic phase of the heart. If a first large change in the amplitude during a diastolic phase of a pulse wave corresponding to the diastolic phase of the heart, it is highly probable that a motion artifact has occurred. Therefore, a motion artifact flag is set. Next, it is checked if the amplitude in the next diastole is changing by more than 30%. if it is presumed that the occurrence of cough is highly probable, a cough flag is set. if it is neither the motion artifact nor the cough, then a yawn flag is set.