Wearable Stress Sensing With Underside cEDA Electrodes

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Solution Overview

Problem

Existing wearable biometric monitoring devices face challenges in accurately measuring continuous electrodermal activity (cEDA) for detecting acute stress events due to the need for continuous skin contact, which is not feasible with electrodes mounted on the top face, limiting the effectiveness of stress detection and monitoring.

Innovation Solution

A wearable computing device with biometric sensor electrodes on the underside for continuous skin contact, combined with a Momentary Stress Algorithm (MSA) that processes time-series data from multiple sensors, applies filtering techniques, and selects models to calculate stress indicators, triggering notifications or functions when thresholds are exceeded.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If electrodes are mounted on the top face of the device, then the device structure is simpler, but continuous skin contact cannot be maintained for accurate cEDA measurement

Engineering Contradiction:
ImprovecEDA measurement accuracyVSAvoidelectrode positioning complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent inverts the conventional electrode placement by positioning cEDA electrodes on the underside of the wearable device rather than the top face. This inversion enables continuous skin contact during normal wear, allowing accurate cEDA measurements without requiring user intervention to maintain contact.

Inventive Principle:
Principle #13The other way round (Inversion)

2Duration of action of stationary object

If electrodes are positioned on the underside for continuous skin contact, then continuous cEDA measurement is enabled, but the device requires more careful design and positioning

Engineering Contradiction:
Improvecontinuous measurement durationVSAvoiddevice design complexity
Core Design Contradiction:
Duration of action of stationary objectVSDevice complexity

Solution Approach 1:

The patent implements continuous cEDA measurement by positioning electrodes on the underside of the device, enabling uninterrupted skin contact during normal wear. This continuous configuration allows the device to maintain measurement functionality over extended periods without requiring user intervention or frequent repositioning.

Inventive Principle:
Principle #20Continuity of useful action

3Measurement precision

If multiple sensors and filtering techniques are applied, then stress detection accuracy is improved, but processing complexity increases

Engineering Contradiction:
Improvestress event detection accuracyVSAvoiddata processing complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent segments the stress detection process into distinct stages: collecting data from multiple sensors (cEDA, heart rate, temperature, accelerometer), processing each sensor type through specific filtering techniques, and then integrating the processed data to detect stress events. This segmentation allows complex processing to be managed systematically.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent applies filtering techniques to sensor data in advance before stress event detection. By pre-processing the data to remove artifacts and noise, the system prepares clean data for accurate stress detection, reducing the computational burden during the actual detection phase.

Inventive Principle:
Principle #10Preliminary action

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

The device provides accurate and continuous stress detection, enabling users to be aware of acute stress events and offering countermeasures, enhancing stress awareness and management.

Implementation Method 1

skin conductance is calculated using the measured electrical impedance

Methodology Applied
Scientific EffectElectrical Impedance: Electrical Resistance

Implementation Method 2

input of other sensors (e.g., photoplethysmography data (such as amplitude))

Methodology Applied
Scientific EffectPhotoplethysmography: Absorption (EM radiation)

Data Source

PatentUS20260060578A1Momentary Stress Algorithm for a Wearable Computing Device
Publication Date: 2026.03.05 GOOGLE LLC
  • US20260060578A1 patent drawing
  • US20260060578A1 patent drawing
  • US20260060578A1 patent drawing

AI summary

A method of monitoring stress of a user includes receiving a plurality of time-series data inputs from a plurality of biometric sensor electrodes of a wearable computing device. The time-series data inputs includes continuous electrodermal activity data and at least one of heart rate data, skin temperature data, and heart rate variability data. The method also includes processing the time-series data inputs using a plurality of filtering techniques in sequence. Further, the method includes selecting a model from a plurality of models based on types of data inputs received as the time-series data inputs to calculate an indicator of a physiological response of the user at a certain time. Thus, the selected model is tailored to use all of the time-series data inputs in the calculation of the indicator of the physiological response. Further, the method includes controlling a function of the device when the indicator of the physiological response exceeds a threshold.