Pulse Oximetry Sensor with Elastic Inelastic Segmentation

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Solution Overview

Problem

Pulse oximetry sensors face signal artifacts due to patient and sensor motion, leading to inaccurate measurements, as the flexible nature of both disposable and reusable sensors causes changes in light path and tissue deformation, which current signal processing filters cannot fully mitigate.

Innovation Solution

The development of a pulse oximetry sensor with an elastic material for the sensor body, combined with an inelastic region connecting the emitter and detector, which accommodates patient movement while maintaining a fixed optical distance, and a strategically routed sensor cable to reduce pressure and motion artifacts.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If the sensor body is made flexible to accommodate patient movement, then patient comfort and adaptability are improved, but signal artifacts increase due to changes in light path and tissue deformation

Engineering Contradiction:

Improveadaptability to patient movementVSAvoidmeasurement accuracy

Core Design Contradiction:

Adaptability or versatilityVSMeasurement precision

Solution Approach 1:

The sensor body is divided into elastic portions that accommodate movement and inelastic portions that maintain stable optical properties. This segmentation allows different regions to serve different functions: the elastic portions provide flexibility and patient comfort, while the inelastic portions ensure measurement accuracy by maintaining consistent light path geometry.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different regions of the sensor body are assigned different material properties. The elastic portions are located in areas that experience movement, while the inelastic portions are positioned to maintain the optical path between emitter and detector. This local differentiation of material properties resolves the contradiction between flexibility and measurement stability.

Inventive Principle:

Principle #3Local quality

2Measurement precision

If the sensor body is made rigid to maintain fixed optical distance, then measurement precision is improved, but patient comfort and adaptability deteriorate

Engineering Contradiction:

Improveoptical distance stabilityVSAvoidpatient comfort

Core Design Contradiction:

Measurement precisionVSEase of operation

Solution Approach 1:

The sensor body is segmented into rigid and flexible sections. The rigid inelastic portions maintain the fixed optical distance between emitter and detector for accurate measurements, while the flexible elastic portions conform to patient anatomy and accommodate movement, providing comfort and ease of operation.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The sensor employs local quality differentiation where specific regions have rigid properties for optical stability and other regions have flexible properties for patient comfort. This allows the sensor to simultaneously achieve measurement precision and ease of operation in different locations.

Inventive Principle:

Principle #3Local quality

3Measurement precision

If signal processing filters are used to mitigate motion artifacts, then measurement accuracy is improved, but the filters cannot fully eliminate artifacts from regular movements

Engineering Contradiction:

Improvesignal accuracyVSAvoidartifact reduction effectiveness

Core Design Contradiction:

Measurement precisionVSReliability

Solution Approach 1:

The sensor prevents motion artifacts before they occur by maintaining a fixed optical distance through inelastic portions, rather than attempting to filter them out after detection. This preliminary structural stabilization ensures that regular movements do not generate artifacts that would require filtering.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent converts the potential harm of patient movement into a benefit by using elastic materials that accommodate movement while isolating the optical path. The movement is allowed in the elastic portions but does not translate into optical artifacts because the inelastic portions maintain stable geometry, effectively turning motion into a non-problematic feature.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

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 design significantly reduces signal artifacts by stabilizing the optical distance and minimizing tissue deformation, enhancing measurement accuracy and patient comfort without compromising sensor resistance to movement.

Implementation Method 1

a non-invasive sensor that transmits electromagnetic radiation, such as light, through a patient's tissue and that photoelectrically detects the absorption and scattering of the transmitted light in such tissue

Methodology Applied

Scientific EffectPhotoelectric detection: Photoelectric Effect

Implementation Method 2

a sensor body comprising an elastic material; and an emitter and a detector disposed on the sensor body, wherein sensor body is substantially inelastic in at least part of a region of the sensor body connecting the emitter and the detector

Methodology Applied

Scientific EffectElasticity: Elasticity

Data Source

PatentUS8175671B2Medical sensor for reducing signal artifacts and technique for using the same

Publication Date: 2012.05.08 COVIDIEN LP

AI summary

A sensor may be adapted to reduce motion artifacts by mitigating the effects of the tissue moving within the sensor. A sensor is provided with an elastomeric sensor body adapted to accommodate patient motion. Further, a sensor is provided in which the sensor cable is arranged to mitigate its pressure on a patient's tissue.