# US 12,180,381 B2 · Conductive liquid metal microparticles comprising hydrogen-doped liquid metal oxide, conductive ink comprising same, and preparation method therefor

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- Number: US 12,180,381 B2
- Document ID: US12180381B2
- Status: Granted
- Kind: B2
- Application number: 17/781,117
- Filed: 2020-12-14
- Published: 2024-06-20
- Granted: 2024-12-31
- Earliest claimed: 2020-03-18
- Assignees: Postech Research and Business Development Foundation
- Applicants: POSTECH Research and Business Development Foundation
- Inventors: Unyong Jeong; Veerapandian Selvaraj
- Web page: https://patentgrep.com/patent/US12180381B2

## CPC

- C09D 11/037: characterised by the pigment
- C09D 11/52: Electrically conductive inks
- C09D 11/03: characterised by features other than the chemical nature of the binder
- C09D 11/033: characterised by the solvent
- C09D 11/102: containing macromolecular compounds obtained by reactions other than those only involving unsaturated carbon-to-carbon bonds
- C09D 11/106: containing macromolecular compounds obtained by reactions only involving carbon-to-carbon unsaturated bonds
- H01B 1/02: mainly consisting of metals or alloys
- C09D: COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR (cosmetics A61K; processes for applying liquids or other fluent materials to surfaces, in general, B05D; staining wood B27K5/02; glazes or vitreous enamels C03C; natural resins, French polish, drying-oils, driers, turpentine, per se, C09F; polishing compositions other than French polish, ski waxes C09G; adhesives or use of materials as adhesives C09J; materials for sealing or packing joints or covers C09K3/10; materials for stopping leaks C09K3/12; processes for the electrolytic or electrophoretic production of coatings C25D)
- H01B: CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES (selection for magnetic properties H01F1/00; waveguides H01P {; printed circuits H05K})

## Abstract

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.

## Claims

### Claim 1

A conductive liquid metal microparticle comprising:
a core comprising a liquid metal; and
a shell surrounding the core and comprising a hydrogen-doped liquid metal oxide.

### Claim 2 (depends on 1)

The conductive liquid metal microparticle of claim 1, wherein the shell further comprises a liquid metal oxide.

### Claim 3 (depends on 1)

The conductive liquid metal microparticle of claim 1, wherein the hydrogen-doped liquid metal oxide is represented by Chemical Formula 1: [Chemical Formula 1] MxOyHz where M is a liquid metal, x is in a range of 0<x≤1, y is in a range of 0<y≤1, and z is in a range of 0<z≤1.

### Claim 4 (depends on 1)

The conductive liquid metal microparticle of claim 1, wherein the liquid metal comprises at least one selected from the group consisting of gallium (Ga), indium (In), tin (Sn), gold (Au), and alloys thereof.

### Claim 5 (depends on 4)

The conductive liquid metal microparticle of claim 4, wherein the alloy comprises at least one selected from the group consisting of a eutectic gallium-indium alloy (EGaIn) and Galinstan.

### Claim 6 (depends on 1)

The conductive liquid metal microparticle of claim 1, further comprising an elastic polymer coupled to the shell and positioned outward.

### Claim 7 (depends on 6)

The conductive liquid metal microparticle of claim 6, wherein the elastic polymer comprises an ethylene (—C—C—) moiety in a chain thereof.

### Claim 8 (depends on 6)

The conductive liquid metal microparticle of claim 6, wherein the elastic polymer comprises at least one selected from the group consisting of ethylene-vinyl acetate copolymer (PEVA), styrene-ethylene-butylene-styrene block copolymer (SEBS), and aliphatic polyurethane.

### Claim 9 (depends on 1)

The conductive liquid metal microparticle of claim 1, having a particle size of 1 to 10 μm.

### Claim 10 (depends on 1)

The conductive liquid metal microparticle of claim 1, wherein the shell has a thickness of 0.5 to 10 nm.

### Claim 11 (depends on 1)

A conductive ink comprising: an elastic polymer; the conductive liquid metal microparticle of claim 1; and a solvent.

### Claim 12 (depends on 11)

The conductive ink of claim 11, wherein the elastic polymer comprises an ethylene (—C—C—) moiety in a chain thereof.

### Claim 13 (depends on 11)

The conductive ink of claim 11, wherein the elastic polymer comprises at least one selected from the group consisting of ethylene-vinyl acetate copolymer (PEVA), styrene-ethylene-butylene-styrene block copolymer (SEBS), and aliphatic polyurethane.

### Claim 14 (depends on 11)

The conductive ink of claim 11, wherein the solvent comprises at least one selected from the group consisting of toluene, tetrahydrofuran (THF), hexane, and heptane.

### Claim 15 (depends on 11)

The conductive ink of claim 11, wherein the conductive ink comprises a radical initiator, the radical initiator is a peroxide-based compound, and the peroxide-based compound includes at least one selected from the group consisting of dicumyl peroxide, dibenzoyl peroxide, and di-tert-butyl peroxide.

### Claim 16 (depends on 1)

A method of preparing a conductive ink, the method comprising: (a) preparing a mixed solution by mixing an elastic polymer, a liquid metal, a radical initiator, and a solvent; (b) ultrasonically treating the mixed solution to produce a conductive ink containing the conductive liquid metal microparticles of claim 1.

### Claim 17 (depends on 16)

The method of claim 16, wherein step (a) is performed at a temperature in a range of 70° C. to 100° C.

### Claim 18 (depends on 16)

The method of claim 16, wherein the mixed solution contains the liquid metal in an amount of 5% to 90% by volume of with respect to 100% by volume of the elastic polymer.

### Claim 19 (depends on 16)

The method of claim 16, wherein step (b) comprises (b-1) ultrasonically treating the mixed solution to cause the elastic polymer to react with the radical initiator to generate hydrogen radicals (H·) and forming a core including the liquid metal; (b-2) oxidizing the liquid metal on the surface of the core to form a liquid metal oxide surrounding the core; and (b-3) forming conductive liquid metal microparticles, each having a shell containing a hydrogen-doped liquid metal oxide formed by bonding of the hydrogen radical (H·) and oxygen of the liquid metal oxide.

### Claim 20 (depends on 19)

The method of claim 19, further comprising step (b-4) in which the elastic polymer binds to the shell after step (b-3) to form conductive liquid metal microparticles containing a polymer bonded to the shell.