Wrist-Mounted PPG Sensor for Continuous Stress Monitoring
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional methods for evaluating human stress using photoplethysmography (PPG) face limitations, including restrictions on human subjects and the need for large-scale systems that can increase stress levels and restrict manual operations, such as typing on a computer.
Innovation Solution
A method and apparatus that evaluate human stress by analyzing the amplitude of the pulse component, change in baseline, and variation in peak-to-peak interval of the PPG signal, using statistical methods like t-tests and ANOVA to calculate stress indexes, allowing for both short-term and long-term tests, and incorporating low-pass filtering to remove noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional PPG measuring devices (glove type or finger contact type) are used to obtain PPG signals, then reliable stress evaluation can be achieved, but the human subject is restricted from performing manual operations
Solution Approach 1:
The invention segments the PPG measurement function from the traditional glove/finger contact interface, implementing it as a standalone sensor module that can be positioned on the wrist. This allows the measurement function to be separated from the hand operations, enabling subjects to perform manual tasks while the wrist-mounted sensor continuously monitors PPG signals for stress evaluation.
Solution Approach 2:
The wrist-mounted PPG sensor acts as an intermediary device that captures physiological stress indicators through blood flow changes in the wrist area, providing an alternative measurement path that does not interfere with hand-based manual operations while maintaining reliable stress evaluation capabilities.
2Reliability
If multiple physiological signals (ECG, EEG, EMG, PPG, GSR, SKT) are collected to evaluate human stress, then comprehensive stress evaluation can be achieved, but the system complexity and restrictions on human subjects increase
Solution Approach 1:
The invention extracts and utilizes only the PPG signal from among multiple physiological signals for stress evaluation. By focusing on the pulse component amplitude, baseline spread range, and peak-to-peak interval of the PPG signal, the system achieves reliable stress evaluation without requiring the complex multi-signal collection system, thereby reducing device complexity and restrictions on subjects.
Solution Approach 2:
The PPG signal serves multiple functions in this invention: it provides both cardiovascular health information and stress evaluation data. By analyzing different parameters (pulse component amplitude for vascular stiffness, baseline spread and peak-to-peak interval for stress levels) from the same PPG signal, the system achieves comprehensive evaluation without requiring separate measurement devices for each parameter.
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 enables reliable and minimally invasive stress evaluation, allowing for continuous monitoring without restricting human subjects, even during activities like typing, by using a PPG measuring device with a block letter 'C' shape and signal processing units to calculate stress indexes effectively.
Implementation Method 1
PPG indicates a signal corresponding to a quantity of light reflected from a selected part of a human body after being irradiated by light having a particular wavelength emitted from a light source of a light emitting device
Data Source
AI summary
A method of evaluating human stress using photoplethysmography (PPG) includes defining at least one PPG parameter, radiating light having at least one wavelength, which reacts to a blood component to be measured, at a measuring target and measuring a PPG signal from the measuring target during a predetermined period of time, and evaluating a level of human stress using a plurality of stress indexes obtained from the PPG parameter.