The truth is often stranger than fiction is a well-known adage. Whether this is true for science fiction or not is a subject for debate. Science does however tend to move steadily towards a reality that was originally portrayed as science fiction.

Solid-state components with semiconducting devices and fixed metallic tracks are used for modern electronic technologies like computers and smart phones. Being able to create truly elastic electronic components is a dream that is slowly but surely being realized. These soft circuit systems will act more like live cells, communicating with each other to form new circuits and moving around autonomously. They will therefore not be stuck in one configuration like solid-state components are.

The most promising path for realizing that dream are liquid metals. Non-toxic alloys of gallium in particular are incredibly malleable. The essentials needed for making electronic circuits using liquid metals is an atomically thin semiconducting oxide skin as well as a highly conductive metallic core.

A group from the School of Engineering at RMIT University in Melbourne, Australia led by Professor Kourosh Kalantar-zadeh immersed liquid metal droplets in water to work out how to allow liquid metal to move autonomously. Kalantar-zadeh noted that thus far they have not understood the basics of how liquid metal interacts with surrounding fluid, although it is known that putting droplets in another liquid with an ionic content breaks the symmetry across them. This then allows them to move around in three dimensions freely.









The team investigated the effect of adjusting the concentrations of base, salt and acid components in the water. The liquid metal droplets change shape and moved without any need for external electronic, mechanical or optical stimulants because of this simply tweaking of the water’s chemistry.

This discovery led to the creation of moving objects, pumps and switches that operated independently – self-propelling liquid metals driven by the composition of the neighboring fluid. The research has possible applications in a range of industries such as biomedicine and smart engineering solutions. The foundation has now been laid for using “electronic” liquid metals to make 3D electronic components and displays on request. It may even be possible to build a 3D liquid metal humanoid on demand in the future. Hopefully, if the T-1000 Terminator is one day recreated in real life, it will have better programming!

Dr Ali Zavabeti, first author of the paper, detailed precisely how fluid moves around on the liquid metals’ surfaces. He not only explains the precise conditions in which liquid metals can be stretched or moved, but also how they can make different flows. This shows how liquid metals can be used and manipulated. Control is gained through the electric charges that collect on the surface of liquid metal droplets, together with their oxide skin.

Full study has been published in the Nature Communications journal.