I don’t know about you, guys, but my fav thing in Terminator 2 was probably the T1000 model, with the liquid metal structure doing all kinds of weird things. Wouldn’t it be cool to have a material like that? Unfortunately, at the moment we don’t, but morphing liquid metal does exist. And it is fairly common, too, in speakers and hard drives, for a start. This material is known as ferrofluid.
Ferrofluids are made up of tiny magnetic fragments of iron (nanoparticles) suspended in oil (often kerosene) with a surfactant to prevent clumping (usually oleic acid). In fact, they can be made at home (with care!) using discarded stuff like old audio or video tapes, acetona and finished toner cartridges, or buy it online, although it is a bit on the expensive side (around 100 USD per 8oz). The resulting colloidal suspension is very sensitive to magnetic fields. The idea is pretty simple: magnetic nanoparticles are attracted to the field, but can not clump, so they sort of cover the field center like a liquid layer. Besides, the surface will go all spiky, as nanoparticles will try to align themselves with the field just like iron filings do with a magnet. If one moves the magnetic field, ferrofluid acts accordingly.
The main problem preventing us from building our very own T1000 from our folks’ ol’ video collection is that resulting shapes are quite unpredictable, not nearly solid enough and require constant manipulation of a magnetic field to bend them to our will. It is quite unlikely that we’ll build any human-like thing using ferrofluids in the near future , but in the meantime people is doing neat stuff playing around with the thing, like Sachiko Kodama‘s dynamic sculptures.