Since the movie “Terminator 2: Judgement Day” debuted in 1991, pop culture has been fascinated with the T-1000 Terminator — a killing machine made completely of liquid metal that could assume the identity of others, walk through jail cells and even camouflage itself as a puddle on the floor.

Obviously, current robots can’t do these advanced mechanics, but the technology is getting closer with the development of new liquid metals that can be manipulated in a 3D space with magnets.

Metals such as gallium and certain alloys are liquid at room temperature but still have properties such as high conductivity, low melting point and high deformability. Such properties make these metals attractive for use in soft robots and flexible electronics, according to researchers at Beihang University in Beijing.

By adding magnetic particles, such as nickel or iron, researchers found the liquid metals can be manipulated using magnets. Most liquid metals, because of high surface tension, can only move horizontally and must be immersed completely in liquid to avoid forming a paste.

Instead, researchers wanted to make a magnetic liquid metal that could move and stretch both horizontally and vertically without needing to be immersed in a liquid.

How they did it

To accomplish this, the researchers first worked with the material submerged in liquid and then added iron particles to a droplet of a gallium, indium and tin alloy immersed in hydrochloric acid. A gallium oxide layer formed on the droplet surface, which lowered the surface tension of the liquid metal. When two magnets were applied in opposite directions, the droplet could be stretched to almost four times its resting length.

The liquid metal could also be manipulated by connecting two immersed, horizontal electrodes and then used to light up an LED bulb. The liquid metal could also stretch vertically and then move horizontally to connect two electrodes — the first one exposed to air and the second one submerged in hydrochloric acid. Researchers said that when manipulated in this way the magnetic liquid metal was reminiscent of an upright walking amphibian.

The complete research can be found in the journal Applied Materials and Interfaces.

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