Wearable Stress Sensor Using Ventilation Rate Above Predicted
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Solution Overview
Problem
Current methods fail to accurately measure the level of stress in individuals or animals by distinguishing between ventilation rates caused by activity and those caused by stress responses.
Innovation Solution
A wearable device with sensors to track ventilation rates and movement, calculating the 'Ventilation Rate Above Predicted' (VRAP) by comparing actual ventilation rates to stress-free minimum values, which correlates with stress levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If ventilation rate is used as a stress indicator, then stress monitoring is enabled, but measurement precision deteriorates due to confounding effects of activity
Solution Approach 1:
The patent introduces an intermediary variable (activity level) to mediate the relationship between ventilation rate and stress. By measuring both ventilation rate and activity level separately, and using activity level as a confounder in the analysis, the system can isolate the stress component of ventilation rate, thereby improving measurement precision while maintaining stress monitoring capability
Solution Approach 2:
The patent changes the parameter being measured from raw ventilation rate to a derived stress metric (ventilation rate adjusted for activity). By transforming the measurement approach and using activity-level-adjusted ventilation rates, the system achieves both reliable stress monitoring and precise measurement that accounts for activity confounds
2Measurement precision
If multiple sensors are added to distinguish activity and stress effects, then measurement precision improves, but device complexity increases
Solution Approach 1:
The patent applies multi-functionality by using a single accelerometer sensor to serve dual purposes: measuring both activity level and, indirectly, stress-related movements. This universal approach allows the system to distinguish between activity-induced and stress-induced ventilation rate changes without requiring separate sensors for each function, thereby improving measurement precision while limiting the increase in device complexity
3Productivity
If real-time stress monitoring is implemented, then productivity of stress detection is improved, but use of energy increases
Solution Approach 1:
The patent implements periodic sampling of physiological data at optimized intervals rather than continuous monitoring. By adjusting the sampling frequency based on activity level and stress state, the system achieves real-time stress detection capability while reducing overall energy consumption compared to continuous high-frequency monitoring
Solution Approach 2:
The patent applies dynamic adjustment of monitoring intensity based on current physiological state. When activity level is high, the system adjusts sampling parameters accordingly, allowing real-time detection during critical periods while reducing energy consumption during stable states, thus balancing productivity and energy use
Data Source
AI summary
Wearable devices that track activity and ventilation rates for use on humans or animals that breathe air and methods of use thereof, are provided. The device is generally suitable to be worn around a subject's chest, and typically contains one or more sensors. Generally, one sensor detects respiratory rate and another sensor detects acceleration (i.e. activity). The method and apparatus can be used to determine the minimum ventilation rate for a given degree (intensity) of movement to construct the ‘stress-free’ relationship between ventilation rate and movement. Then measured values of ventilation rate in relation to movement are compared to the predicted, minimum ventilation rates (stress-free values) and the minimum ‘stress-free’ values are subtracted from the measured values. The difference (Ventilation Rate Above Predicted’ (VRAP)) correlates with stress in the subject.