Wearable Textile Optical Sensor for Depth-Resolved Tissue Oxygenation

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Solution Overview

Problem

Existing methods for preventing pressure injuries lack spatial and depth resolution in measuring tissue oxygenation changes, particularly at locations beneath the skin surface where tissue necrosis begins, and often introduce additional pressure points.

Innovation Solution

A wearable textile sensor using flexible optical fibers that emit and receive near-infrared light at multiple wavelengths, allowing for spatially resolved oxygen saturation distribution measurements without introducing additional pressure points, integrated into garments like socks, underpants, or leggings.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If pressure monitoring is used to prevent pressure injuries, then pressure distribution can be monitored, but spatial and depth resolution to detect tissue oxygenation changes at locations deep beneath the skin surface is insufficient

Engineering Contradiction:
Improvespatial and depth resolutionVSAvoidsensor structure
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The sensor is divided into multiple independent optical fibers with different source-detector separation distances, allowing measurements at different tissue depths. Each fiber pair acts as an independent measurement channel, enabling spatially resolved oxygen saturation profiling through the tissue depth without requiring a single complex deep-penetration sensor.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The invention transitions from single-point pressure measurement to multi-dimensional optical measurement by using multiple optical fibers with varying source-detector separations. This creates a depth dimension in measurements, allowing detection of tissue oxygenation changes at different depths beneath the skin surface, effectively adding a spatial dimension to the monitoring capability.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

2Measurement precision

If near-infrared spectroscopy is used to measure tissue oxygenation, then oxygen saturation can be detected, but spatial resolution to locate oxygenation changes at specific pressure points is insufficient

Engineering Contradiction:
Improvespatial resolutionVSAvoidfiber arrangement
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

Different regions of the sensor have different fiber configurations optimized for local measurement needs. The sensor can be arranged to concentrate measurement points at specific anatomical locations prone to pressure injuries, with each location having its own optimized fiber geometry and source-detector separation distances tailored to that specific measurement zone.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The same optical fiber structure serves multiple functions: it acts as both a light delivery medium and a spatially resolving measurement tool. The multiple fibers with different separations simultaneously provide both oxygen saturation measurement and depth-resolved spatial information, eliminating the need for separate imaging and spectroscopy systems.

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

3Loss of information

If traditional pressure monitoring methods are used, then pressure distribution can be assessed, but the direct relation between surface pressure and deep tissue oxygen saturation cannot be established

Engineering Contradiction:
Improveinformation on tissue oxygenationVSAvoidmeasurement capability
Core Design Contradiction:
Loss of informationVSDifficulty of detecting and measuring

Solution Approach 1:

The optical fibers act as intermediaries that bridge the gap between surface-level pressure monitoring and deep tissue oxygenation assessment. By placing optical fibers in direct contact with the tissue at the same location as pressure sensors, the system creates a coupled measurement system where optical measurements provide the missing deep tissue oxygenation information that pressure sensors alone cannot obtain.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The invention merges pressure sensing and optical oxygenation measurement into a single integrated sensor system. Multiple optical fibers are bundled together with pressure sensors at the same measurement location, allowing simultaneous acquisition of both pressure and tissue oxygenation data, thereby establishing the direct relationship between surface pressure and deep tissue oxygen saturation.

Inventive Principle:
Principle #5Merging (Combining)

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 continuous, non-invasive monitoring of tissue oxygen saturation and pressure, providing real-time feedback to prevent pressure injuries by detecting critical oxygen levels and prompting movement, thus preventing tissue necrosis.

Implementation Method 1

a first light generating unit configured to generate and couple light of a first wavelength into the first ends of the first optical fibers and to generate and couple light of a second wavelength into the second ends of the first optical fibers

Methodology Applied
Scientific EffectLight emission: Light

Implementation Method 2

measure changes in tissue oxygenation by means of near-infrared spectroscopy

Methodology Applied
Scientific EffectNear-infrared spectroscopy: Absorption Spectroscopy

Data Source

PatentEP4340721B1Medical device comprising a wearable textile sensor to protect against pressure injuries
Publication Date: 2026.04.22 UNIVERSITY OF BERN
  • EP4340721B1 patent drawingFigure 1a~2
  • EP4340721B1 patent drawingFigure 3a~3c
  • EP4340721B1 patent drawingFigure 4

AI summary

A medical device (1) for determining an oxygen saturation in a tissue of a subject, comprises: a sensor (2) comprising a flexible textile (10) comprising a plurality of first optical fibers (11) and a plurality of second optical fibers (12). It further comprises a first light generating unit (3) configured to generate and couple light of a first wavelength into the first ends (11a) of the first optical fibers (11) and to generate and couple light of a different second wavelength into the second ends (12a) of the first optical fibers (11). The respective first optical fiber (11) is configured to emit light via a light emitting section (21) to irradiate tissue of the subject, the light emitting section (21) being arranged between the first end (11a) and the second end (11b) of the respective first optical fiber (11), The respective second optical fiber (12) comprises a light receiving section (22) configured to receive light coming from the tissue, the light receiving section (22) being arranged between the first end (12a) and the second end (12b) of the respective second optical fiber (12). The sensor (2) further comprises a first light detector unit (4) to detect light received by the light receiving section (22), and an analyzing unit (5) configured to determine an oxygen saturation value of the tissue using intensities of light detected by the first light detector unit (4).