Liquid metal flowing

Liquid metals such as gallium and mercury possess unique properties that make them essential in modern technologies, from thermometers to flexible circuits.

About this subject

Liquid metals are metallic substances that remain in a liquid state near room temperature. The best known is mercury, which freezes at -38.83 °C and boils at 356.73 °C, historically used in thermometers and barometers. However, its toxicity has led to replacement by safer alternatives such as gallium, which melts at just 29.76 °C, allowing it to melt in the palm of your hand. Alloys like Galinstan (gallium, indium, and tin) are liquid at room temperature and non-toxic, making them useful in medical devices and the electronics industry.

An innovative application of liquid metals is in flexible electronics. They can be injected into microscopic channels to create stretchable circuits that maintain conductivity even when deformed. This technology is crucial for wearable sensors, soft robots, and foldable displays. Moreover, their high thermal conductivity makes them excellent coolants in high-performance systems, such as nuclear reactors and advanced computers.

Interestingly, gallium has the widest liquid temperature range among metals (from 29.76 °C to 2.204 °C), and its low vapor pressure makes it safe for laboratory use. Liquid sodium is used as a coolant in fast nuclear reactors, but it reacts violently with water. Despite advances, handling liquid metals requires caution: mercury can contaminate environments for decades, while gallium-based alloys can react with aluminum and other metals, potentially embrittling structures.

Frequently Asked Questions

Which liquid metal is safe to touch with bare hands?

Gallium is safe for brief contact as it melts at 29.76 °C and is non-toxic. However, it can stain skin and react with aluminum. Mercury, on the other hand, is highly toxic and should be avoided.

Where are liquid metals used today?

They are used in alternative thermometers, flexible circuits for wearable electronics, coolants in high-performance computers, and medical sensors, leveraging their electrical and thermal conductivity.

Is Galinstan really liquid at room temperature?

Yes, Galinstan (an alloy of gallium, indium, and tin) remains liquid down to -19 °C, making it a non-toxic alternative to mercury for applications such as thermometers and electrical contacts.