Wearable Sweat Ammonia Sensor for Non-Invasive Stress Monitoring

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Solution Overview

Problem

Current wearable devices for monitoring vital signs and stress conditions often require invasive procedures, such as blood tests for lactate measurement, which are not correlated with sweat values, and lack continuous, non-invasive, and bloodless monitoring capabilities.

Innovation Solution

A device with first and second sensors that non-invasively measure ammonia in sweat and vital signs like respiration or heart activity, respectively, combined with an evaluation device to generate a scalar stress measure, using ion-selective electrodes and a transport system for continuous sweat flow, allowing direct evaluation and reference value comparison.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If invasive procedures like blood tests are used for monitoring stress conditions, then measurement precision is improved, but ease of operation deteriorates and object-affected harmful factors increase

Engineering Contradiction:
Improvestress measurement accuracyVSAvoidmonitoring convenience
Core Design Contradiction:
Measurement precisionVSEase of operation

Solution Approach 1:

The patent uses sweat as an intermediary substance to indirectly measure stress-related parameters. Instead of directly analyzing blood (invasive), the device measures ammonia and other metabolites in sweat that correlate with stress conditions, providing accurate stress assessment without invasive procedures. The sweat analysis serves as a mediator between the physiological state and the measurement device.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The invention replaces the mechanical/invasive blood sampling system with a non-invasive sweat collection and analysis system. Electronic sensors detect chemical compositions in sweat, substituting the need for physical blood extraction and laboratory analysis with automated, contactless electronic measurement.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

2Measurement precision

If invasive blood tests are used for lactate measurement, then measurement precision is improved, but reliability deteriorates due to lack of continuous monitoring

Engineering Contradiction:
Improvelactate measurement accuracyVSAvoidcontinuous monitoring capability
Core Design Contradiction:
Measurement precisionVSReliability

Solution Approach 1:

The device enables continuous monitoring of stress-related parameters through ongoing sweat analysis. Unlike discrete blood tests, the wearable device continuously collects sweat and measures metabolite concentrations, providing uninterrupted data streams that reliably track stress conditions over time during activities.

Inventive Principle:
Principle #20Continuity of useful action

Solution Approach 2:

Sweat serves as a continuous intermediary that reflects real-time physiological stress states. The device leverages the continuous production and secretion of sweat to provide ongoing measurement of stress-related metabolites, eliminating the need for repeated invasive sampling while maintaining measurement precision.

Inventive Principle:
Principle #24Intermediary (Mediator)

3Measurement precision

If multiple sensors and evaluation devices are integrated, then measurement precision is improved, but device complexity increases

Engineering Contradiction:
Improvecomprehensive stress assessmentVSAvoidsensor integration complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent combines multiple sensing functions (ammonia detection, other metabolite analysis, physiological parameter monitoring) into a single integrated wearable device. The evaluation unit processes data from all sensors together, merging what would otherwise be separate measurement systems into one cohesive unit that comprehensively assesses stress conditions.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The wearable device is designed as a universal monitoring system that can measure multiple stress-related parameters simultaneously through different sensors. The evaluation unit handles various types of data (chemical composition, physiological signals) and integrates them into a unified stress assessment, making the device versatile rather than specialized for a single measurement.

Inventive Principle:
Principle #6Universality (Multi-functionality)

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 rapid, continuous, non-invasive, and bloodless vital parameter measurement, providing a comprehensive stress assessment by correlating ammonia and vital sign data, facilitating safe and effective monitoring of stress conditions during activities like sports or medical treatments.

Implementation Method 1

The first sensor (2) is designed in such a way that it non-invasively generates a measured value (MV1) based on a proportion of ammonia in the sweat of the living being (100)

Methodology Applied
Scientific EffectIon-selective electrode detection:

Implementation Method 2

The device (1) has in addition at least a transport device (9), which is designed in such a way that it transports the sweat towards the first sensor (2) and/or away from the first sensor (2)

Methodology Applied
Scientific EffectTransport device mechanism:

Data Source

PatentEP3275362B1Device for monitoring a condition of a living being
Publication Date: 2022.12.28 FRAUNHOFER GESELLSCHAFT ZUR FORDERUNG DER ANGEWANDTEN FORSCHUNG EV
  • EP3275362B1 patent drawingFigure 1
  • EP3275362B1 patent drawingFigure 2
  • EP3275362B1 patent drawingFigure 3~4

AI summary

The invention relates to a device (1) for monitoring the condition of a living being (100). The device (1) comprises a first sensor (2), a second sensor (3), and an evaluation device (4). The first sensor (2) non-invasively generates a measured value based on the proportion of ammonia in the sweat of the living being (100). The second sensor (3) generates a measured value relating to the respiration or cardiac activity of the living being (100). Based on the measured values ​​of the first and second sensors (2, 3), the evaluation device (4) generates a scalar measure of the stress on the living being (100). The invention further relates to a corresponding method.