Now, surface tension describes, in crude terms, the attractive forces between the molecules at the surface of a material. Less of it means that it can’t hold together in the same way, and it begins to flatten out in a pancake-like shape.
The electrode, which is slightly tilted, causes this flatter droplet to move away from it. This removes it from the electrochemical reaction, which causes it to pop up again into a more spherical shape. This cycle continues at a fairly quick rate, which mimics the action of a beating heart – and it allows the drop to move uphill.
Change the electrical current and change the heartbeat, up to 610 beats per minute. It’s extremely cool stuff. Check out this video by New Scientist demonstrating the wizardry at hand:
It’s extremely early days, of course; this is just a proof-of-principle technique at present. If, however, you can imagine gallium-infused muscles for a moment – perhaps in prosthetics or so-called “soft robots” – it’s not difficult to see how electrical currents could be used more precisely to make them move.
Considering how malleable gallium is, and how frequently it’s already used in electronics, one can see how this won’t remain a sci-fi concept for forever. Besides, as the authors note, plenty of biological species already use “exquisite methods” for using internal fluids to propel themselves around and engage in essential biochemistry.
By contrast, human fluidic technology still relies on “inelegant” mechanical flow systems. Gallium hearts, then, could be our way of catching up with evolutionary biology.
That, or we've just seen the start of the development of the T-1000. A tad unnervingly, the team behind the paper explained that this time-traveling killer served to be the project's initial source of inspiration.