Eutectic gallium-indium (EGaIn) EGaIn

spore: profile
id: egain
spore_version: 0.2
family: low-melting-metals-and-solders
name: Eutectic gallium-indium (EGaIn)
abbreviation: EGaIn
role: liquid-metal conductor for stretchable electronics
category: metals
type: heavy-metals
summary: |
  Eutectic gallium-indium (EGaIn) is a liquid metal alloy of gallium and indium, written as 75.5 % Ga and 24.5 % In by weight in Table 1 of a 2021 review. Its melting point is 15.5 °C in that table and 15.7 °C on a vendor product page. The review gives a thermal conductivity of 26.4 W/m.K for EGaIn. A 2012 study of oxidised EGaIn gives a density of 6.25 g/ml at 50 °C and a pure-liquid surface tension of 445 mN/m. The review says air forms a self-passivating Ga2O3 skin about 0.5 to 3 nm thick on Ga-based liquid metals.
best_for: Liquid-metal conductors that must stay liquid at room temperature, such as stretchable circuits and liquid-metal-embedded elastomers
weakest_at: 'Oxide skin: the Ga2O3 film forms in air and adds a yield stress to the liquid, so flow and droplet shape depend on the oxide'
identity:
  formula: 'GaIn: gallium-indium eutectic, about 75.5 % Ga and 24.5 % In by weight in the review'
  source: alizadeh-2021
  where: Table 1, Eutectic Gallium-Indium row (75.5% Ga, 24.5% In, weight basis). Formula GaIn also printed on the PubChem record for CID 16213646 and on the ProChem product 1880 page.
  designations:
    - system: Trade name
      code: EGaIn
      source: alizadeh-2021
      where: Introduction, sentence naming Eutectic Gallium-Indium (EGaIn), and Table 1 row label
tags:
  applications:
    - electronics-and-chips
properties:
  - benchmark: density
    label: Density of EGaIn in the liquid state (2012 study)
    value: 6.25
    unit: g/ml
    scope: material
    conditions:
      temperature: 50 °C, liquid state (the test temperature the paper gives for its measurements)
      composition: 77 % Ga with 23 % In as mixed by the authors; the weight or atomic basis is not stated
    method: Value given in the experimental section of the paper, as printed in the authors' text
    status: ground
    note: The same paper mixes 77 % Ga with 23 % In, while the review's Table 1 gives 75.5 % Ga and 24.5 % In by weight.
    source: arxiv-1201-4828
    where: Experimental section, paragraph after Fig. 1 (eGaIn has a density of 6.25 g/ml)
  - benchmark: surface_tension
    label: Pure-liquid surface tension of EGaIn (fit with the oxide term removed)
    value: 445
    unit: mN/m
    scope: material
    conditions:
      basis: fitted surface tension of the pure liquid (gamma 0) after the oxide-skin term is removed from the pendant-drop model
      method_detail: pendant drop in hydrochloric acid baths of varying concentration
      temperature: not stated in this passage
    method: Fit of the authors' effective surface tension model to pendant-drop data
    status: ground
    note: Printed as 445 ± 19 mN/m, the paper's own fit uncertainty.
    source: arxiv-1201-4828
    where: Pendant-drop results, paragraph containing the gamma 0 (eGaIn) fit
  - benchmark: surface_tension
    label: Literature surface tension of eGaIn quoted by the 2012 study
    value: 444
    unit: mN/m
    scope: material
    conditions:
      basis: literature value the authors cite for eGaIn
      temperature: not stated
    method: Value quoted in the authors' comparison with the literature
    status: ground
    source: arxiv-1201-4828
    where: Pendant-drop results, same paragraph as the gamma 0 fit, literature values in brackets
  - benchmark: melting_point
    label: Melting point of EGaIn (review Table 1)
    value: 15.5
    unit: °C
    scope: material
    conditions:
      composition: 75.5 % Ga, 24.5 % In by weight, as printed in Table 1
    method: Printed in Table 1 of the review, which cites its references 1 and 17
    status: ground
    source: alizadeh-2021
    where: Table 1, Eutectic Gallium-Indium row, melting temperature column
  - benchmark: melting_point
    label: Melting point of EGaIn (ProChem product 1880)
    value: 15.7
    unit: °C
    scope: material
    conditions:
      grade: Gallium-indium eutectic, product 1880, purity 99.999% as printed
      composition: formula GaIn printed, no weight or atomic percentage printed
    method: Vendor product page, Information section
    status: ground
    source: prochem-1880
    where: Information section, sentence giving a melting point of 15.7 °C
  - benchmark: thermal_conductivity
    label: Thermal conductivity of EGaIn (review Table 1)
    value: 26.4
    unit: W/m.K
    scope: material
    conditions:
      composition: 75.5 % Ga, 24.5 % In by weight
      temperature: not stated
    method: Printed in the EGaIn row of Table 1 as 26.4 W/m.K
    status: ground
    source: alizadeh-2021
    where: Table 1, Eutectic Gallium-Indium row, thermal conductivity column
  - benchmark: oxide_layer_thickness
    label: Ga2O3 oxide skin thickness on Ga-based liquid metals (review range)
    value: 0.5
    value_high: 3
    bound: range
    unit: nm
    scope: material
    conditions:
      environment: air or oxygen-saturated elastomer at room temperature
      basis: range the review gives for the Ga2O3 skin on Ga-based liquid metals, which include EGaIn; not a measured EGaIn value
    method: Range quoted in the introduction of the review
    status: ground
    source: alizadeh-2021
    where: Introduction, paragraph on the self-passivating Ga2O3 oxide layer
  - benchmark: band_gap
    label: Band gap of the Ga2O3 oxide skin (quoted in the review)
    value: 4.85
    unit: eV
    scope: material
    conditions:
      basis: approximately 4.85eV as printed for the n-type Ga2O3 semiconductor, not for the alloy itself
    method: Value quoted in the introduction of the review
    status: ground
    note: Describes the oxide skin, not the metal. Included because the review gives it with the oxide layer.
    source: alizadeh-2021
    where: Introduction, paragraph on the self-passivating Ga2O3 oxide layer
corrosion:
  - environment: Air or oxygen at room temperature
    headline: A thin Ga2O3 skin forms on EGaIn in air, about 0.5 to 3 nm thick, according to the review.
    effect: The review says the skin lowers the surface tension of droplets and acts as an elastic membrane until the surface stress exceeds a critical value it prints as 0.5–0.6 N/m-1. The skin breaks and reforms at once. The review gives no corrosion rate for EGaIn.
    rating: low
    conditions:
      basis: literature statement for Ga-based liquid metals; the review runs no EGaIn test
      exposure: air or oxygen-saturated elastomers
    source: alizadeh-2021
    where: Introduction, paragraph on the self-passivating Ga2O3 oxide layer
  - environment: Oxidised EGaIn in pendant-drop tests, compared with the oxide-free limit
    headline: The oxide skin raises the apparent surface tension and adds a yield stress to EGaIn.
    effect: The authors show that an oxide layer adds a size-dependent effective surface tension and a yield stress. In the limit of large hydrochloric acid concentration the effective tension reduces to the surface tension of the pure liquid, which their fit gives as 445 mN/m for EGaIn.
    rating: moderate
    conditions:
      basis: pendant-drop and rheometer tests in hydrochloric acid baths of varying concentration
      temperature: 50 °C for the paper's mechanical measurements
    source: arxiv-1201-4828
    where: Pendant-drop results, discussion of Eqn. 5 and the limit of large acid concentration
risks:
  hazards: []
  failure_risks:
    - mode: Oxide skin adds yield stress to the liquid
      trigger: Oxidised EGaIn in air, with the Ga2O3 skin intact
      consequence: The authors attribute the larger, size-dependent effective surface tension in pendant-drop tests to the yield stress of the oxidised liquid, so an intact oxide film changes droplet shape and flow compared with the pure metal.
      severity: moderate
      source: arxiv-1201-4828
      where: Pendant-drop results, paragraph on the yield stress of oxidised liquid metals
    - mode: Oxide skin breaks under high surface stress
      trigger: Surface stress above the critical value the review prints as 0.5–0.6 N/m-1
      consequence: The skin breaks and reforms at once, so printed or moulded droplets hold their shape. The review treats this as useful for printing and moulding, so the severity is low.
      severity: low
      source: alizadeh-2021
      where: Introduction, paragraph on the self-passivating Ga2O3 oxide layer
  side_effects: []
  handling:
    - text: The 2012 study prepared the alloy in a quartz tube with argon gas cycled through the tube to inhibit oxidation.
      source: arxiv-1201-4828
      where: Experimental section, paragraph on producing eGaIn
    - text: The 2012 study used hydrochloric acid of varying concentration to control the oxide layer in its tests.
      source: arxiv-1201-4828
      where: Experimental section, sentence on the acid bath
  mitigations:
    - text: The authors use hydrochloric acid baths to control the oxide. At large acid concentration the effective surface tension reduces to that of the pure liquid.
      source: arxiv-1201-4828
      where: Pendant-drop results, discussion of Eqn. 5
uses:
  - application: electronics-and-chips
    device: Liquid-metal-embedded elastomers for stretchable electronics
    example: The review names eutectic Ga-In (EGaIn) and Ga-In-Sn (Galinstan) as popular liquid-metal alloys for liquid-metal-embedded elastomers used in stretchable electronics.
    source: alizadeh-2021
    where: Introduction, paragraph on Ga-based alloys in LMEEs
  - application: electronics-and-chips
    device: Stretchable circuit with liquid metal injected into elastomer microchannels
    example: 'The review''s Figure 12 shows the injection route: a mould is cast in elastomer, the elastomer is sealed, GaIn is injected into the microchannels, and external copper wires are inserted.'
    source: alizadeh-2021
    where: Figure 12 caption (injection filling, steps e and f)
  - application: electronics-and-chips
    device: LMEE-based nanotriboelectric power source for wearable electronics
    example: The review lists an LMEE-based nanotriboelectric device for renewable power supply for wearable electronics. The sentence does not name the alloy.
    source: alizadeh-2021
    where: Section on wearable electronics applications, sentence citing reference 21
supply:
  - subject: Gallium
    abundance: 'USGS: the average gallium content of bauxite is 50 parts per million.'
    producers:
      - country: China
        share_percent: 99
        year: 2025
    critical_lists: []
    recycling: 'USGS: old scrap, none. Substantial quantities of new scrap from GaAs-based device manufacture were reprocessed to high-purity gallium at one facility in New York.'
    substitutes:
      - 'USGS: substitutes exist for GaAs and GaN in some applications; the chapter does not discuss liquid-metal alloy uses.'
    source: usgs-mcs2026-gallium
    where: Events, Trends, and Issues (China 99% of worldwide primary low-purity gallium production; year is the report year 2025); Bauxite paragraph (50 parts per million); Recycling line; Substitutes line
  - subject: Gallium metal imports to the United States
    producers:
      - country: Canada
        share_percent: 28
        year: 2024
      - country: Japan
        share_percent: 22
        year: 2024
      - country: China
        share_percent: 18
        year: 2024
      - country: Germany
        share_percent: 16
        year: 2024
    critical_lists: []
    source: usgs-mcs2026-gallium
    where: Import Sources (2021-24) line, metal shares; the year is the end of the 2021 to 2024 period as printed
  - subject: Indium
    producers:
      - country: China
        share_percent: 70
        year: 2025
    critical_lists: []
    recycling: 'USGS: indium is most commonly recovered from ITO scrap in Japan and the Republic of Korea; data on the quantity recovered were not available.'
    substitutes:
      - 'USGS: antimony tin oxide, carbon nanotube coatings, PEDOT and copper or silver nanowires have been developed or explored as alternatives to ITO coatings.'
    source: usgs-mcs2026-indium
    where: Events, Trends, and Issues (China accounting for 70% of the world total); Recycling line; Substitutes line
  - subject: Indium imports to the United States
    producers:
      - country: Republic of Korea
        share_percent: 25
        year: 2024
      - country: Japan
        share_percent: 22
        year: 2024
      - country: China
        share_percent: 12
        year: 2024
      - country: Canada
        share_percent: 11
        year: 2024
    critical_lists: []
    source: usgs-mcs2026-indium
    where: Import Sources (2021-24) line; the year is the end of the 2021 to 2024 period as printed
documents:
  - title: 'Robust and Multifunctional Liquid-Metal Embedded Elastomers for Ultrastretchable Electronics: a Short Review (arXiv 2104.07327)'
    type: paper
    url: https://arxiv.org/pdf/2104.07327
    year: 2021
  - title: Effect of oxidation on the Mechanical Properties of Liquid Gallium and Eutectic Gallium-Indium (arXiv 1201.4828)
    type: paper
    url: https://arxiv.org/pdf/1201.4828
    year: 2012
  - title: Gallium-indium eutectic, product 1880 (ProChem Online product page)
    type: datasheet
    url: https://prochemonline.com/product/galliumindiumeutectic-1880
  - title: 'PubChem: Gallium Indium eutectic (CID 16213646), formula and identifiers only'
    type: database
    url: https://pubchem.ncbi.nlm.nih.gov/compound/16213646
  - title: 'USGS Mineral Commodity Summaries 2026: Gallium'
    type: report
    url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-gallium.pdf
    year: 2026
  - title: 'USGS Mineral Commodity Summaries 2026: Indium'
    type: report
    url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-indium.pdf
    year: 2026
gaps:
  - No EGaIn safety data sheet or PubChem GHS classification was read in this run. The Sigma-Aldrich page timed out, the American Elements page returned HTTP 403, and the PubChem record for CID 16213646 has no GHS section. Hazards are left empty.
  - 'Electrical conductivity is left out: the review''s Table 1 prints 3.46 * 10^6 S/m, which is exponent notation.'
  - 'Viscosity is left out: the 2012 study prints nominal and measured values with exponents (for example 1.86 × 10−3 with a mN·s unit), which cannot be recorded in plain form.'
  - The surface tension column of Table 1 prints 624 with no unit, so it is not entered.
  - The ProChem page prints a specific gravity of 6.25 with no unit, so it is not entered. The 2012 study's density of 6.25 g/ml is used instead.
  - 'Composition conflicts: 75.5 % Ga with 24.5 % In by weight in the review, 77 % Ga with 23 % In with no basis stated in the 2012 study, and formula GaIn only on the ProChem page.'
  - The critical surface stress of 0.5–0.6 N/m-1 is quoted in prose only, because the review prints its unit as N/m-1.
  - No EGaIn-specific corrosion test on aluminium or other structural metals was found in the sources read.
  - Critical-mineral status of gallium and indium was not found in the fetched USGS text, so critical_lists is empty.
  - Atomic weights of gallium and indium were not fetched, so the recipe parts carry no atomic_weight.
  - Property count is 8, below the standard of 12 or more, because the sources give few EGaIn-specific values with a printed unit and no exponent. The 2012 study's other yield-stress values were not entered because their test conditions were not clear from the text read.
  - Surface tension and band gap are not in spores/property-canon.yaml. The names surface_tension, oxide_layer_thickness and band_gap are used as they are.
  - No space, vacuum, outgassing or radiation data for EGaIn were found in the sources read.
  - The 2012 study's year is taken from its arXiv identifier (1201); no printed date was read.
sources:
  alizadeh-2021:
    title: 'Robust and Multifunctional Liquid-Metal Embedded Elastomers for Ultrastretchable Electronics: a Short Review'
    id: arXiv 2104.07327
    url: https://arxiv.org/pdf/2104.07327
    year: 2021
    kind: paper
    license: cited, not reproduced
  arxiv-1201-4828:
    title: Effect of oxidation on the Mechanical Properties of Liquid Gallium and Eutectic Gallium-Indium (Xu, Oudalov, Guo, Jaeger and Brown)
    id: arXiv 1201.4828
    url: https://arxiv.org/pdf/1201.4828
    year: 2012
    kind: paper
    license: cited, not reproduced
  prochem-1880:
    title: Gallium-indium eutectic, product 1880 (ProChem Online product page)
    id: ProChem Online product 1880
    url: https://prochemonline.com/product/galliumindiumeutectic-1880
    year: 2026
    kind: web
    license: vendor page, cited not reproduced
  usgs-mcs2026-gallium:
    title: Mineral Commodity Summaries 2026, Gallium
    id: USGS MCS 2026, February 2026
    url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-gallium.pdf
    year: 2026
    kind: report
    license: public domain (USGS)
  usgs-mcs2026-indium:
    title: Mineral Commodity Summaries 2026, Indium
    id: USGS MCS 2026, February 2026
    url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-indium.pdf
    year: 2026
    kind: report
    license: public domain (USGS)
license: CC-BY-4.0
updated: '2026-11-01'
review:
  status: draft
  method: assistant
  checked_values: 8
  unreachable: 1
  caveats: 3
  note: Written by an AI assistant on 2026-11-01 from the sources listed. 8 property values were read in this run. No EGaIn safety data sheet could be opened.
story:
  recipe:
    line: EGaIn is a binary liquid-metal alloy of gallium and indium. The review prints its composition as 75.5 % Ga and 24.5 % In by weight. The 2012 study mixed 77 % Ga with 23 % In, so the exact ratio differs between sources. The 2012 study made the alloy by heating the mixed metals in a quartz tube under flowing argon, then cooling them to room temperature.
    parts:
      - name: Gallium
        symbol: Ga
        share: 75.5 % by weight (review Table 1)
        role: The main constituent. It stays liquid near room temperature and forms the thin Ga2O3 oxide skin in air.
      - name: Indium
        symbol: In
        share: 24.5 % by weight (review Table 1)
        role: Lowers the melting point so the alloy is liquid at room temperature, which is what makes it useful as a liquid conductor.
  risk_groups:
    - title: For people
      verdict: No hazard classification found in any source we hold
      lead: We could not open a supplier safety data sheet for EGaIn, so this profile records no hazard classification. Search results from suppliers showed different hazard codes, and those are not used here.
      points:
        - label: Safety data sheet
          line: The EGaIn data sheets we tried did not open in this run. Check the sheet for the lot you buy before handling.
        - label: Skin and eyes
          line: No source we hold gives skin or eye effects for EGaIn.
    - title: In a device
      lead: The oxide skin and its yield stress are the main behaviour to design for.
      points:
        - label: Oxide skin
          line: The review says a thin Ga2O3 skin forms in air, about 0.5 to 3 nm thick, and breaks and reforms under high surface stress.
        - label: Flow
          line: The 2012 study attributes a larger, size-dependent effective surface tension in pendant drops to the yield stress of the oxidised liquid.
  why: Eutectic gallium-indium (EGaIn) is a liquid metal at room temperature that conducts electricity and heat like a metal. Its melting point is 15.5 °C in the review and 15.7 °C on a vendor page, so it stays liquid in a normal room. Its main use in the sources is as the conductor in stretchable circuits made from liquid-metal-embedded elastomers. The trade-off is a Ga2O3 oxide skin that forms in air and changes how the liquid flows.
  uses:
    - where: Stretchable electronics
      line: A 2021 review names EGaIn, with Galinstan, as one of the popular liquid-metal alloys for liquid-metal-embedded elastomers used in stretchable electronics.
    - where: Stretchable circuits by injection
      line: The review illustrates a route in which the liquid metal is injected into microchannels in a cured elastomer, and copper wires are added at the ends.
    - where: Wearable power
      line: The review also lists an LMEE-based nanotriboelectric device for renewable power supply for wearable electronics. The sentence does not name the alloy.
  can_do:
    - label: Stay liquid at room temperature
      benchmark: melting_point
      line: The melting point is 15.5 °C in the review's Table 1 and 15.7 °C on a vendor page (product 1880, purity 99.999% as printed).
    - label: Conduct heat
      benchmark: thermal_conductivity
      line: The review's Table 1 prints a thermal conductivity of 26.4 W/m.K for EGaIn, with no temperature stated.
    - label: Hold a shape after printing
      benchmark: oxide_layer_thickness
      line: The review says the Ga2O3 skin, about 0.5 to 3 nm thick, lets droplets be printed and moulded.
  compare: EGaIn belongs to the Ga-based liquid-metal family of the review. Within the review's Table 1, EGaIn has a higher melting point and a slightly higher thermal conductivity than Galinstan, the other Ga-based alloy the review names. Both alloys carry the same oxide-skin trade-off. The compare table lists the values this profile holds.
  compare_rows:
    - label: Melting point
      benchmark: melting_point
    - label: Thermal conductivity
      benchmark: thermal_conductivity
    - label: Density
      benchmark: density
  handling:
    - Prepare or heat the alloy under an inert gas such as argon, as the 2012 study did, to limit oxide formation.
    - Expect a thin Ga2O3 oxide skin in air, and account for it if the flow must behave like the pure metal.
    - Check a current safety data sheet for each lot before handling. This profile records no hazard codes.
  good_for:
    - Liquid metal at room temperature. The melting point is 15.5 °C in the review and 15.7 °C on a vendor page.
    - Stretchable conductors. The review names EGaIn as a popular liquid-metal alloy for liquid-metal-embedded elastomers.
  watch_out:
    - Oxide skin. The Ga2O3 skin forms in air and adds a yield stress to the liquid, per the 2012 study.
    - 'Composition differs between sources: 75.5 % Ga in the review and 77 % Ga in the 2012 study.'
    - No source we hold gives a corrosion test on aluminium or other structural metals for EGaIn.
  verdict: EGaIn is a practical room-temperature liquid metal when the oxide skin is designed in. Its hazard data are the main gap in this profile.