Elastic Pillar Biomedical Electrode for Stable Low-Resistance Sensing

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Solution Overview

Problem

Existing biomedical electrodes suffer from low contact resistance, measurement instability, and poor wearing stability, particularly in electroencephalographic applications.

Innovation Solution

A biomedical electrode design featuring a plate-shaped support portion with elastic pillar portions and a conductive resin layer, where the elastic pillar portion's rubber hardness is adjusted to a specific range (35 to 65 durometer hardness at 37°C) to enhance followability and stability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the rubber hardness of the elastic pillar portion is not optimized, then the electrode can be manufactured with standard materials, but the contact resistance increases and measurement stability deteriorates

Engineering Contradiction:
Improvemeasurement stabilityVSAvoidmanufacturing complexity
Core Design Contradiction:
ReliabilityVSEase of manufacture

Solution Approach 1:

The patent applies parameter changes by optimizing the rubber hardness of the elastic pillar portion to a specific range (35-65 durometer hardness at 37°C). This parameter optimization resolves the contradiction by improving measurement stability and reducing contact resistance while maintaining manufacturability through standard material specifications.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent utilizes phase transitions by specifying the rubber hardness at a specific temperature (37°C), which corresponds to body temperature. This temperature-dependent property optimization ensures consistent performance in the physiological environment, improving measurement stability while maintaining manufacturing feasibility.

Inventive Principle:
Principle #36Phase transitions

2Adaptability or versatility

If the elastic pillar portion is made too soft, then the followability to the measurement target improves, but the wearing stability and contact resistance increase

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

Solution Approach 1:

The patent resolves this contradiction by changing the physical parameter of rubber hardness to an optimized range (35-65 durometer). This range provides sufficient softness for followability to the measurement target (scalp or skin) while maintaining enough rigidity for wearing stability and low contact resistance.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent employs composite materials by using silicone rubber with specific hardness characteristics in the elastic pillar portion. This composite material approach allows simultaneous achievement of followability and wearing stability by selecting rubber compounds with optimized viscoelastic properties.

Inventive Principle:
Principle #40Composite materials

3Reliability

If the elastic pillar portion is made too hard, then the wearing stability improves, but the followability to the measurement target and contact resistance decrease

Engineering Contradiction:
Improvewearing stabilityVSAvoidfollowability
Core Design Contradiction:
ReliabilityVSAdaptability or versatility

Solution Approach 1:

The patent resolves this contradiction by optimizing the rubber hardness parameter to prevent excessive hardness. By maintaining the hardness within 35-65 durometer at 37°C, the electrode achieves sufficient wearing stability while preserving adequate followability to the measurement target, avoiding the pitfalls of overly rigid materials.

Inventive Principle:
Principle #35Parameter changes

4Reliability

If the rubber hardness is not controlled within the specified range, then the manufacturing process is simpler, but the contact resistance and measurement stability deteriorate

Engineering Contradiction:
Improvecontact resistanceVSAvoidhardness control precision
Core Design Contradiction:
ReliabilityVSManufacturing precision

Solution Approach 1:

The patent resolves this contradiction by establishing a specific hardness range (35-65 durometer at 37°C) that balances contact resistance and manufacturing precision. This parameter specification allows for controlled material selection and processing while achieving low contact resistance and high measurement stability.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent applies mechanics substitution by replacing complex mechanical adjustment mechanisms with a material property-based solution. Instead of mechanically adjusting the hardness during manufacturing, the invention uses rubber compounds with inherently optimized hardness values within the specified range, simplifying the manufacturing process while ensuring reliable contact resistance performance.

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

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 design achieves low contact resistance, improved measurement stability, and enhanced wearing comfort by optimizing the rubber hardness of the electrode, thereby increasing brain wave acquisition efficiency.

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

Implementation Method 2

a conductive resin layer that is formed to cover distal ends of the elastic pillar portions

Methodology Applied
Scientific EffectElectrical conduction: Conduction (electrical)

Data Source

PatentEP3991654B1Biomedical electrode, biomedical sensor, and biosignal measurement system
Publication Date: 2025.12.03 SUMITOMO BAKELITE CO LTD
  • EP3991654B1 patent drawingFigure 1A~1B
  • EP3991654B1 patent drawingFigure 2
  • EP3991654B1 patent drawingFigure 3A~3B

AI summary

A biomedical electrode according to the present invention 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 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 higher than 35 and 65 or lower.