In the wildest dreams of each of us, at least as far as science fiction is concerned, there are certainly the Hollywood shape-shifting T1000s. Wella group of researchers has created a Robot similar to a Terminator capable of dissolving in response to precise stimuli and then recomposing itself. Thanks to alternating magnetic fields and drawing inspiration from a particular marine creature, they have created a first miniature prototype. Without forgetting, however, that the merit is also of the materials specifically used to build the model.
How the Terminator robot is made
The properties of the model are due to the particular chemical composition of the alloy that composes it. The robot is in fact a mixture of ferromagnetic particles including Neodymium, Iron, and Boron in a liquid metal matrix. With the particularity that the latter has a low melting point; in fact the mixture is immersed in pure gallium.
The substance consists of what is called MPTM, or magnetoactive phase transitional matter. As can be guessed from the name, it can pass from the solid to the liquid phase in a reversible manner. Thanks to an alternating magnetic field, it heats up and melts, then solidifies again at room temperature.
Thus, MPTMs uniquely combine high mechanical strength, high load capacity and locomotion speed. In strength they reach 21.2 MPa, instead in stiffness at 1.98 GPa, loading up to 30 Kg at more than 1.5 m/s, in solid phase. While in the liquid they have an excellent morphological adaptability (elongation, cracking, breaking, etc.).
Characteristics of the league and first results
NdFeB microparticles are embedded in the gallium matrix with clear phase separation between NdFeB and the liquid metal. The mixing process is carried out mechanically to the point that the clear phase separation is seen via electronic scanning.
The researchers used pure gallium as it has a melting point (29.8°C) close to room temperature.. And this of course allows for a rapid solid-liquid phase transition under ambient conditions.
The solid gallium matrix also prevents the embedded NdFeB microparticles from moving or rotating. This thus allows solid MPTMs to maintain a fixed and stable magnetic polarity. However, this freedom of movement limits the liquid-phase mobility of all MPTM; whereas in the solid phase, with the application of certain magnetic field strengths, scientists recorded different speeds.
In particular then, the researchers conducted several tests in the solid and liquid phase; for example making the material perform jumps, rotations and various movements. What got the terminator screaming was the particular configuration in which they ran one of the tests. Indeed the scientists molded the substance into a lego-like figure placed behind bars in a cage. Well, once the alternating magnetic field has been applied, the video clearly shows the figure melting and then recomposing itself outside the bars.
The unexpected creature from which it takes inspiration: the sea cucumber
At this point, after much mentioning it, you would expect Hollywood to have influenced the scientists at Carnegie Mellon together with the Chinese University. But things are different from what one might think; as in many studies of this type nature, and in particular a sea creature, are responsible at least in part for what they have achieved.
The oluturias or oloturoidei are the main source of inspiration for the MPTM; Also called sea cucumbers, these creatures have little to do with vegetables. They are in fact animals that live on the seabed all over the globe, belonging to the class of echinoderms. They have an elongated cylindrical appearance (reminiscent of cucumbers) with anus and mouth located on opposite sides.
In particular, the oluturias are characterized by so-called rigid calcareous spicules all over their body, and they use their mouth to feed themselves by filtering the water. Most of them are benthic, i.e. they live permanently attached to the seabed and some are even sessile (fixed to the substrate). Despite this, however, they can move in case of danger of uprooting and predators.
And so far nothing so spectacular or characteristic, some might observe. But it would be enough to mention one of their defense strategies to make comparisons with Hollywood and superhero films. In fact, sea cucumbers have great regenerative abilities: they can actually eviscerate some of their organs. Water lungs, long intestines, and their single gonad are expelled to distract enemies and aid escape; to then be able to regenerate everything in a short time.
To complete its entire curriculum, this marine creature has a lot of importance for the marine ecosystem and biodiversity. In fact, like their terrestrial cousins, such as earthworms, they perform the function of scavengers and are detrivores. But not only that, it also seems to help buffer the acidification effect of the oceans.
Applications of the Robot Terminator
Sea cucumber is capable of reversibly altering the stiffness of its tissue to improve its carrying capacity. Thanks to this feature it can prevent physical damage from the environment. Just like what researchers have managed to achieve with the robot terminator.
Ok, all very nice some might say, but in practice what can it be used for, what have scientists thought of to use it profitably? Obviously not to take a first step towards what would be a real robot terminator. Researchers in fact, among other applications, have also thought of the medical field and possible contributions in the repair of systems that are difficult to reach.
An initial result was achieved by making the MPTM carry out extraction and transport tasks. In a simulated stomach model, the team showed how the micromachine could switch to a liquid phase. This is to wrap itself around other foreign objects in the stomach itself, and then become solid again. And from there allow both the robot and its payload to be extracted.
A similar test saw the robot dump its cargo at pre-set points, all within the simulated stomach model. This, according to the authors it is a demonstration of its potential as a drug delivery system.
Finally, as a last application, a simulation showed how the liquid form of the robot could become a “universal screw”. All by sneaking into spaces that are difficult to access and sliding into a grip of the screw, solidifying. In short, the potential is there but don’t expect a terminator robot like the Hollywood T1000!
