Biomedical Electrode Hardness Control for Wear and Signal Stability

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Solution Overview

Problem

Existing biomedical electrodes face challenges in wearing stability and measurement stability, particularly in controlling followability to bioelectrical potential variations and ensuring comfort during repeated use.

Innovation Solution

A biomedical electrode with a plate-shaped support portion and elastic pillar portions made of silicone rubber, featuring a conductive resin layer with a specific thickness and durometer hardness range (15-35 Shore A) to enhance wearability and measurement accuracy.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the rubber hardness of the biomedical electrode is increased to improve measurement stability, then measurement stability is improved, but wearing stability and comfort deteriorate

Engineering Contradiction:
Improvemeasurement stabilityVSAvoidwearing stability
Core Design Contradiction:
ReliabilityVSEase of operation

Solution Approach 1:

The patent applies parameter changes by precisely controlling the rubber hardness within the range of 15-35 Shore A. This specific parameter range resolves the contradiction by finding the optimal balance point where the electrode is soft enough to conform to the scalp surface (improving wearing stability) while maintaining sufficient structural integrity for stable electrical contact (improving measurement stability).

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent applies local quality by differentiating the rubber hardness requirements for different parts of the electrode structure. The pillar portion contact surface requires specific hardness (15-35 Shore A) for optimal performance, while other parts of the electrode can have different material properties to satisfy their specific functional requirements, thus resolving the contradiction between overall wearing comfort and local measurement stability.

Inventive Principle:
Principle #3Local quality

2Ease of operation

If the rubber hardness of the biomedical electrode is decreased to improve wearing comfort, then wearing stability is improved, but measurement stability deteriorates

Engineering Contradiction:
Improvewearing stabilityVSAvoidmeasurement stability
Core Design Contradiction:
Ease of operationVSReliability

Solution Approach 1:

The patent resolves this contradiction by establishing the lower bound of the rubber hardness parameter at 15 Shore A. This prevents the material from becoming too soft, which would cause excessive deformation and loss of electrical contact stability. The parameter control ensures the electrode remains firm enough for reliable measurement while still being soft enough for comfort.

Inventive Principle:
Principle #35Parameter changes

3Strength

If the rubber hardness of the biomedical electrode is increased beyond 35 Shore A, then structural strength is improved, but followability to bioelectrical potential variations deteriorates

Engineering Contradiction:
Improvestructural strengthVSAvoidfollowability
Core Design Contradiction:
StrengthVSAdaptability or versatility

Solution Approach 1:

The patent applies parameter changes by setting the upper bound of rubber hardness at 35 Shore A. This prevents the material from becoming too hard, which would reduce its ability to conform to the contours of the scalp and follow variations in bioelectrical potential. The parameter control maintains the optimal balance between structural strength and adaptability.

Inventive Principle:
Principle #35Parameter changes

4Adaptability or versatility

If the rubber hardness of the biomedical electrode is decreased below 15 Shore A, then followability to scalp surface is improved, but measurement stability deteriorates

Engineering Contradiction:
ImprovefollowabilityVSAvoidmeasurement stability
Core Design Contradiction:
Adaptability or versatilityVSReliability

Solution Approach 1:

The patent resolves this contradiction by establishing the lower bound of the rubber hardness parameter at 15 Shore A. This ensures the electrode maintains sufficient structural strength and rigidity to provide stable electrical contact for reliable measurement, while still being soft enough to follow the scalp surface contours.

Inventive Principle:
Principle #35Parameter changes

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 electrode achieves improved wearing stability and measurement stability by adjusting the rubber hardness of the pillar portions, allowing for reliable bioelectrical potential detection and reduced discomfort during extended use.

Implementation Method 1

an elastic pillar portion that is provided on a first surface of the plate-shaped support portion. The elastic pillar portion is formed of an insulating elastic member including a silicone rubber

Methodology Applied
Scientific EffectElasticity: Elasticity

Data Source

PatentEP3871595B1Bioelectrode, biological sensor, and biological signal measurement system
Publication Date: 2023.09.20 SUMITOMO BAKELITE CO LTD
  • EP3871595B1 patent drawingFigure 1A~1B
  • EP3871595B1 patent drawingFigure 2
  • EP3871595B1 patent drawing

AI summary

A biomedical electrode includes: a plate-shaped support portion; an elastic pillar portion that is provided on a first surface of the plate-shaped support portion; and a conductive resin layer that is formed to cover a distal end of the elastic pillar portion, in which the elastic pillar portion includes a silicone rubber, the conductive resin layer includes a conductive filler and a silicone rubber, and when measured at 37°C according to JIS K 6253 (1997), a type A durometer hardness of a surface of the elastic pillar portion is 15 or higher and 35 or lower.