Liquid metals

If asked to name a metal that is liquid at room temperature, most people will respond with mercury. This is indeed the only metallic element that is liquid at room temperature, and as such it displays some fascinating properties, but its toxicity and volatility makes it very unpleasant to work with. Luckily, you can achieve a non-toxic room temperature liquid metal also by mixing appropriate metallic elements. The interest in such alloys, typically of gallium, indium and tin (GalInStan), has increased rapidly over recent years, largely due to the potential use in flexible electronics. GalInStan behaves quite different from mercury, however, in the sense that you can relatively easily draw filaments from it and it appears to wet many surfaces. Both these characteristics are very attractive for many applications, but they are very surprising, considering that liquid metals normally have exceptionally high surface tension.

The origin of the unusual GalInStan behavior appears to be that it oxidizes instantaneously when exposed to non-inert media, resulting in the formation of a thin solid skin [1]. This allows the alloy to be pulled into jets and strings if done carefully, but the conditions are poorly understood. In one of our research projects we are trying to improve this situation, by investigating the dynamics of filament formation by GalInStan co-flowing with various other liquids.

[1] T.Y. Liu, P. Sen, and C.J.C.J. Kim, J. MICROELECTROMECHANICAL SYSTEMS, 21, 2, pp. 443-450 (2012)

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