galliumindiumtin

Gallium-indium-tin, commonly known as galinstan, is a liquid metal alloy composed of gallium, indium, and tin. In its typical composition Ga68.5In21.5Sn10 by weight, it forms a eutectic alloy that remains liquid at room temperature, with a melting point around minus 19 degrees Celsius. The alloy is noted for being non-toxic relative to mercury, making it appealing for various applications.

Physically, galinstan is a metal with high density and good electrical conductivity. It has a high boiling point and low vapor pressure, allowing it to remain liquid over a wide temperature range. On its surface it rapidly forms a very thin oxide layer of gallium oxide (Ga2O3), which acts as a passivation skin that helps protect the bulk from rapid oxidation and can be stretched as the liquid deforms. This oxide layer also influences wetting behavior and material compatibility.

Applications for galinstan include serving as a non-toxic replacement for mercury in thermometers and other temperature-sensing devices, as well as a coolant or thermal interface fluid in electronics and optics. Beyond thermal management, it is used in soft robotics, stretchable electronics, microfluidics, and laboratory demonstrations of liquid metal behavior. Its unique combination of liquidity at room temperature, electrical conductivity, and relative safety has driven interest across research and industry.

Safety and handling considerations center on its status as a heavy metal with ecological and health considerations if misused. While less toxic than mercury, galinstan should not be ingested, and it can interact with certain materials—most notably it can embrittle aluminum and affect some seals or containers. Proper containment and compatibility assessment are advised in practical applications.