Bio-Electrode Composition for Fast Skin Signal Detection

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Solution Overview

Problem

Current bio-electrodes face challenges in maintaining long-term electric conductivity and biocompatibility due to issues like water evaporation, skin allergies from certain materials, and slow signal detection, particularly in converting ion concentration changes from skin into electrical signals effectively.

Innovation Solution

A bio-electrode composition comprising a polymer compound with repeating units of ammonium, sodium, or silver salts formed with fluorosulfonic acid or fluorosulfonimide, combined with a silicone compound having a polyglycerin structure, which enhances moisture retention and ionic conductivity, enabling quick signal collection and maintaining conductivity even when wet or dry.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If hydrophilic gel containing water and electrolytes is used for bio-electrode, then electric conductivity is improved, but water evaporation during drying process causes loss of electric conductivity

Engineering Contradiction:
Improveelectric conductivityVSAvoidwater evaporation
Core Design Contradiction:
ReliabilityVSLoss of substance

Solution Approach 1:

The patent changes the physical state parameter from wet gel to dry powder form while maintaining ionic conductivity through the specific polymer electrolyte composition. The polymer electrolyte retains ion transport capability in the dry state, eliminating water evaporation issues while preserving electric conductivity for ECG signal detection.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent uses a composite material system combining polymer electrolyte with specific salts (lithium halide, cesium halide, or rubidium halide) to create a solid-state electrode material that integrates both structural integrity and ionic conductivity without requiring water content.

Inventive Principle:
Principle #40Composite materials

2Reliability

If metal nanowire, carbon black, or carbon nanotube is used as electrode material, then electric conductivity is improved, but skin allergy or skin stimulation occurs

Engineering Contradiction:
Improveelectric conductivityVSAvoidskin allergy
Core Design Contradiction:
ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent employs a disposable electrode design where the polymer electrolyte layer serves as a single-use contact material. This eliminates the need for durable, potentially allergenic metals while providing sufficient conductivity for the measurement duration, after which the electrode is discarded rather than reused.

Inventive Principle:
Principle #27Cheap short-living objects (Disposable)

Solution Approach 2:

The polymer electrolyte acts as an intermediary material between the skin and the electrode circuitry. It provides the necessary ionic conductivity for signal detection while its polymer structure avoids direct skin irritation associated with metal nanowires and carbon materials, mediating the interaction between skin and electrode.

Inventive Principle:
Principle #24Intermediary (Mediator)

3Reliability

If noble metal is used for bio-electrode, then electric conductivity is improved, but conversion of ion concentration changes into current becomes inefficient

Engineering Contradiction:
Improveelectric conductivityVSAvoidion to current conversion efficiency
Core Design Contradiction:
ReliabilityVSProductivity

Solution Approach 1:

The patent replaces the electronic conduction mechanism of noble metals with an ionic conduction mechanism in the polymer electrolyte. This substitution enables direct coupling between ion concentration changes at the skin surface and current generation, as the polymer electrolyte's ionic conductivity allows ions to move freely and convert concentration gradients into measurable electrical signals.

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 bio-electrode composition achieves excellent electric conductivity and biocompatibility, allowing for rapid signal detection after attachment to the skin while preventing significant conductivity reduction, making it suitable for long-term use without causing skin irritation.

Implementation Method 1

The water soluble gel contains sodium, potassium, or calcium as the electrolyte in a water soluble polymer for retaining water, and converts changes of ion concentration from skin into electricity

Methodology Applied
Scientific EffectIonic conduction: Conduction (electrical)

Implementation Method 2

a silicone compound having a polyglycerin structure, which enhances moisture retention and ionic conductivity

Methodology Applied
Scientific EffectHygroscopy: Absorption (physical)

Data Source

PatentEP3854303B1Bio-electrode composition, bio-electrode, and method for manufacturing bio-electrode
Publication Date: 2024.03.13 SHIN ETSU CHEMICAL CO LTD
  • EP3854303B1 patent drawingFigure 1~3
  • EP3854303B1 patent drawingFigure 4~6
  • EP3854303B1 patent drawing

AI summary

A bio-electrode composition contains: (A) a polymer compound containing a repeating unit-a having a structure selected from the group consisting of salts of ammonium, sodium, potassium, and silver formed with any of fluorosulfonic acid, fluorosulfonimide, and N-carbonyl-fluorosulfonamide; and (B) a silicone compound having a polyglycerin structure. This bio-electrode composition is able to form a living body contact layer for a bio-electrode which enable quick signal collection after attachment to skin.