The T-1000 is undoubtedly a defining element in film history. Anyone who saw the 1991 film “Terminator 2” at an age receptive to such things will not soon forget this nasty creation of the artificial intelligence Skynet. A machine that can deform, liquify and resurrect at will from a puddle of metal: creepy even when remembered decades later. It’s hard to imagine how the whole thing would have turned out without Arnold Schwarzenegger’s courageous intervention. Hasta la vista, baby!
For a long time, the T-1000 was reassuringly purely fictional. Now, however, a team of researchers led by Carmel Majidi of Carnegie Mellon University in Pittsburgh has recreated him as a Lego figure, complete with his amazing melting abilities, which doesn’t look quite as scary, but still looks quite impressive in the researchers’ video. The little robot stands in a cage, then melts, slides through the bars as a puddle, and then stands up again as a figure, like the T-1000 – although this requires a form, as the researchers concede, which the “real one needs “T-1000 of course not.
The trick is a so-called MPTM material, a magnetically active phase change material. It consists of the metal gallium mixed with microparticles of a mixture of neodymium, iron and boron. These are magnetic and act both as a remote control and as a kind of internal induction cooker: If you apply a magnetic field from the outside, you can not only control the movement of the material, but also heat it up and melt it, all the easier because gallium is already less than 30 degrees Celsius melts.
A robot that can liquefy and reconstruct: this is more than a gimmick
The researchers led by Majidi were able to move the Lego terminator in its cage, melt it, draw the liquid material into a mold and let it cool down again, apparently as if by magic.
This isn’t just a gimmick, it could actually have some practical use. Magnet-controlled mini-robotics is a dynamic field in which some advances have recently been made. But normally you have to make a decision, the researchers explain: Either you can use comparatively strong materials, such as flexible polymers into which ferromagnetic particles are incorporated. Such machines can swim, climb or jump, and sometimes even change their shape. It is possible that such objects could one day be used in the human body, for example to deliver drugs in a targeted manner. But if an opening is smaller than them, they can’t get through.
Or one can work with liquid, magnetically controlled metal droplets, perhaps also with swarms of micromachines that behave similarly to a liquid. However, they are more difficult to control and can only transport very limited loads.
This is where phase change materials have an advantage: they could combine both properties. The team’s Lego robot is still a long way from a practical application, but that’s also obvious.