Hydrogen-Doped Liquid Metal Ink for Stretchable Conductive Circuits

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Solution Overview

Problem

Existing conductive inks for flexible electronic devices face challenges in maintaining conductivity upon deformation or mechanical damage, and they often require chemical etching or mechanical scratching to activate electrical conduction, which is inefficient and can damage the substrate.

Innovation Solution

The development of conductive liquid metal microparticles with a hydrogen-doped liquid metal oxide shell, which are incorporated into a conductive ink along with an elastic polymer and a solvent, allowing for the formation of flexible electrodes with maintained conductivity and excellent adhesion to elastic substrates without the need for oxide layer removal.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If liquid metal is used to form conductive electrodes, then metallic conductivity is achieved, but the oxide layer formed on the surface becomes insulating and prevents electrical conduction

Engineering Contradiction:
Improveelectrical conductivityVSAvoidoxide layer formation
Core Design Contradiction:
ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The patent converts the harmful insulating oxide layer into a beneficial conductive shell by doping it with hydrogen. The oxide layer that naturally forms on the liquid metal surface is transformed into a hydrogen-doped liquid metal oxide shell that exhibits metallic conductivity, eliminating the need for oxide removal while maintaining the liquid metal's flowability and elasticity.

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

Solution Approach 2:

The patent changes the chemical composition parameter of the oxide layer by introducing hydrogen doping. This parameter change transforms the electrical properties of the oxide shell from insulating to conductive, allowing the liquid metal to maintain both its protective oxide layer and electrical conductivity simultaneously.

Inventive Principle:
Principle #35Parameter changes

2Stability of the object's composition

If conductive fillers are embedded in flexible polymer, then high elasticity is achieved, but the distance between fillers increases with stretching causing rapid resistance change

Engineering Contradiction:
ImproveelasticityVSAvoidresistance stability
Core Design Contradiction:
Stability of the object's compositionVSReliability

Solution Approach 1:

The patent changes the physical state parameter of the conductive material from solid particles to liquid metal with a soft oxide shell. This parameter change allows the conductive material to flow and maintain continuous contact during stretching, preventing resistance changes while preserving elasticity.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent creates a composite structure where liquid metal core is surrounded by a hydrogen-doped liquid metal oxide shell, which is then embedded in flexible polymer. This composite design combines the flowability and conductivity of liquid metal with the elasticity of polymer, resolving the contradiction between flexibility and conductivity stability.

Inventive Principle:
Principle #40Composite materials

3Reliability

If chemical etching or mechanical scratching is used to remove oxide layer, then electrical conduction is activated, but the process is inefficient and can damage the substrate

Engineering Contradiction:
Improveelectrical conductionVSAvoidprocess efficiency
Core Design Contradiction:
ReliabilityVSEase of manufacture

Solution Approach 1:

Instead of removing the oxide layer to achieve conductivity, the patent inverts the approach by doping the oxide layer with hydrogen to make it conductive. This inversion eliminates the need for oxide removal processes entirely, simplifying manufacturing and preventing substrate damage.

Inventive Principle:
Principle #13The other way round (Inversion)

Solution Approach 2:

The patent converts the harmful insulating oxide layer into a beneficial conductive component through hydrogen doping. The oxide shell that would normally need to be removed becomes the conductive pathway, eliminating complex activation processes and potential substrate damage.

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

The conductive ink effectively forms circuit lines with metal conductivity that remains constant even under deformation or mechanical damage, and it exhibits excellent adhesion to elastic substrates, maintaining conductivity across a wide temperature and humidity range.

Implementation Method 1

a shell surrounding the core and containing a hydrogen-doped liquid metal oxide

Methodology Applied
Scientific EffectHydrogen doping: Dopants

Data Source

PatentEP4122989B1Conductive liquid metal microparticles comprising hydrogen-doped liquid metal oxide, conductive ink comprising same, and preparation method therefor
Publication Date: 2025.02.05 POSTECH ACADEMY INDUSTRY FOUNDATION
  • EP4122989B1 patent drawingFigure 1~2
  • EP4122989B1 patent drawingFigure 3A~3B
  • EP4122989B1 patent drawingFigure 4A~4B

AI summary

Disclosed are conductive liquid metal microparticles including a hydrogen-doped liquid metal oxide, a conductive ink including same, and a preparation method therefor. The conductive liquid metal microparticle includes a core containing a liquid metal and a shell surrounding the core and containing a hydrogen-doped liquid metal oxide. Since the conductive ink includes the liquid metal microparticles, with the use of the conductive ink, it is possible to form a circuit line exhibiting metal conductivity, an insignificant change in resistance when deformation or mechanical damage occurs, stability of electric characteristics under extreme environment, and good adhesion to an elastic substrate.