Conductive polymer fibers, method and device for producing conductive polymer fibers, biological electrode, device for measuring biological signals, implantable electrode, and device for measuring biological signals

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Solution Overview

Problem

Conductive fibers made from PEDOT-PSS suffer from reduced strength and conductivity in high-humidity environments, leading to cracking and loss of conductivity, and are difficult to handle due to their fine diameter and rigidity, while conventional biological electrodes cause discomfort and skin issues with their hard, hydrophobic materials.

Innovation Solution

Development of conductive polymer fibers where PEDOT-PSS is fixed to silk fibers using a chemical method, with additives like glycerol to enhance moisture resistance and flexibility, and a method for producing these fibers using electrochemical polymerization to improve conductivity and biocompatibility.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conductive fibers are made from PEDOT-PSS to achieve good conductivity and hydrophilicity, then conductivity and biocompatibility are improved, but strength and stability in high-humidity environments deteriorate due to moisture absorption causing cracking and conductivity loss

Engineering Contradiction:
Improveconductivity stabilityVSAvoidtensile strength
Core Design Contradiction:
ReliabilityVSStrength

Solution Approach 1:

The patent combines PEDOT-PSS conductive polymer with hydrophobic materials having low water absorption (such as polyolefins) to create composite fibers. This composite structure allows the PEDOT-PSS to provide conductivity while the hydrophobic component prevents excessive moisture absorption, thereby maintaining both strength and conductivity stability in high-humidity environments

Inventive Principle:
Principle #40Composite materials

Solution Approach 2:

The patent modifies the physical and chemical parameters of the fiber structure by controlling the composition ratio of hydrophobic to hydrophilic components, fiber diameter (1-100 micrometers), and cross-sectional shape. These parameter changes optimize the balance between moisture resistance and conductivity, preventing cracking while maintaining electrical performance

Inventive Principle:
Principle #35Parameter changes

2Reliability

If conductive fibers are made from PEDOT-PSS to achieve good conductivity and hydrophilicity, then biocompatibility is improved, but fiber stability deteriorates due to expansion when absorbing moisture and contraction when dried causing cracking

Engineering Contradiction:
ImprovebiocompatibilityVSAvoidfiber dimensional stability
Core Design Contradiction:
ReliabilityVSStability of the object's composition

Solution Approach 1:

The patent creates composite fibers combining PEDOT-PSS with hydrophobic materials that have low water absorption. This composite structure provides dimensional stability by preventing excessive expansion when the PEDOT-PSS absorbs moisture, while maintaining biocompatibility through the hydrophilic nature of the conductive polymer component

Inventive Principle:
Principle #40Composite materials

Solution Approach 2:

The patent applies different properties to different parts of the fiber structure: the PEDOT-PSS component provides local conductivity and hydrophilicity for biocompatibility, while the hydrophobic component provides overall dimensional stability and moisture resistance, creating a functionally differentiated composite structure

Inventive Principle:
Principle #3Local quality

3Adaptability or versatility

If fine conductive fibers with diameter of approximately 10 microns are produced to achieve good flexibility, then suppleness is improved, but handling difficulty and insufficient strength increase

Engineering Contradiction:
ImprovesupplenessVSAvoidhandling ease
Core Design Contradiction:
Adaptability or versatilityVSEase of operation

Solution Approach 1:

The patent produces ultrafine individual fibers with diameters of 1-100 micrometers that can be easily separated and handled. These segmented fine fibers maintain suppleness for comfort while their individual nature makes them easier to manipulate and position compared to thicker, more rigid conductive materials

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent creates flexible fiber structures with diameters optimized for suppleness (1-100 micrometers) that can conform to body surfaces and contours. These thin fiber structures provide the necessary flexibility and comfort while maintaining sufficient mechanical integrity for practical handling and application

Inventive Principle:
Principle #30Flexible shells and thin films

4Reliability

If conventional metallic electrodes are used to achieve good conductivity, then electrical conduction is improved, but comfort and skin compatibility deteriorate due to hard and hydrophobic material properties

Engineering Contradiction:
Improveelectrical conductionVSAvoidskin irritation
Core Design Contradiction:
ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent creates composite fibers combining conductive PEDOT-PSS polymer with hydrophobic materials, providing both electrical conduction and hydrophilic surface properties. This composite structure enables good electrical performance while the hydrophilic nature improves comfort and reduces skin irritation compared to conventional hydrophobic metallic electrodes

Inventive Principle:
Principle #40Composite materials

Solution Approach 2:

The patent replaces conventional metallic conductive materials with conductive polymer-based fibers. This substitution maintains electrical conduction functionality while changing the mechanical and surface properties from hard and hydrophobic to flexible and hydrophilic, thereby improving skin compatibility and reducing irritation

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 resulting fibers exhibit improved conductivity, strength, and flexibility in both dry and wet states, reducing discomfort and skin issues, and enabling stable long-term bioelectrical signal measurement with minimal invasiveness.

Implementation Method 1

a fixation step in which the base fibers are energized by traveling between electrodes while being perpendicularly raised from the conductor solution, whereby the conductor that impregnates and/or adheres to the base fibers is electrochemically polymerized and fixed thereto

Methodology Applied
Scientific EffectElectrochemical polymerization:

Implementation Method 2

when conductive fibers composed of the aforementioned PEDOT-PSS are used in a high-humidity environment, there is the problem that the PEDOT-PSS absorbs moisture, and that strength (particularly tensile strength) declines

Methodology Applied
Scientific EffectMoisture absorption: Absorption (physical)

Data Source

PatentEP3202317B1Conductive polymer fibers, method and device for producing conductive polymer fibers, biological electrode, device for measuring biological signals, implantable electrode, and device for measuring biological signals
Publication Date: 2022.06.01 NIPPON TELEGRAPH & TELEPHONE CORP
  • EP3202317B1 patent drawingFigure 1~2
  • EP3202317B1 patent drawingFigure 3~5
  • EP3202317B1 patent drawingFigure 6~7

AI summary

Conductive polymer fibers 10, in which a conductor 12 containing a conductive polymer impregnates and/or adheres to base fibers 11, and the aforementioned conductive polymer is PEDOT-PSS.