Galinstan

Galinstan is a eutectic liquid-metal alloy consisting of gallium, indium, and tin. Its typical composition is about 68% gallium, 22% indium, and 10% tin by weight. It has a melting point of about -19°C, so it is liquid at room temperature. The alloy is dense and highly conductive, both thermally and electrically, and remains in the liquid state over a wide temperature range.

A notable property of Galinstan is its surface oxide layer. When exposed to air, a thin film of gallium oxide forms on the surface, which can stabilize the liquid and reduce further oxidation. This oxide skin can be disrupted by mechanical action or chemical cleaning to reveal fresh liquid metal; it then reforms quickly in air.

Applications and uses are centered on its status as a non-mercury, room-temperature liquid metal. It has been proposed and used as a safer replacement for mercury in thermometers and related devices. Beyond thermometry, Galinstan is used in cooling applications and as a thermal interface material in electronics, as well as in microfluidic and soft-robotics contexts where liquid-metal droplets or circuits are advantageous. In laboratory research, it is employed for demonstrations of liquid-metal microchannels and flexible electronic concepts.

Safety and handling are important. Galinstan is generally considered less toxic than mercury, but it is not completely risk-free. It should not be ingested, and exposure should be minimized. Spills should be cleaned carefully to avoid skin exposure and contamination of sensitive materials.