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Engineers Devise Slow Moving Liquid Metal Structures

As far as we know, liquid metal robots from the future have yet to show up. But new research into alloys and lattice materials shows how liquid metal shapes can be deformed and reformed using heat.

Researchers have developed a method of wrapping Field’s alloy - a mixture of bismuth, indium and tin - in a lattice or shell made out of rubber-like elastomers, which gives the liquid metal some useful extra properties. In particular, the liquid metal and elastomer lattice combination can be deformed after heating, and then recover its original shape after being heated up again a second time: not quite a robot rising up out of a lava pit, but the same sort of idea.

“We spent over half a year developing this manufacturing process, because this new lattice material is very hard to process,” says mechanical engineer Pu Zhang from Binghamton University. “You need to find the best materials and processing parameters.”

“Without the shell, it won’t work, because the liquid metal will flow away. The shell skeleton controls the overall shape and integrity, so the liquid metal itself can be confined in the channels.”
Field’s alloy has a relatively low melting point of 62 degrees Celsius (or 144 degrees Fahrenheit), and is used in a variety of ways – as a nuclear coolant, for example. Here, it can ‘remember’ its original shape with the help of the polymer shell.

The shell was produced using a carefully calibrated hybrid manufacturing process involving 3D printing, vacuum casting, and conformal coating (which protects electronics against moisture, dust, chemicals and extreme temperatures).

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