Terminator-Like "Smart Liquid Metal"

Liquid Metal States. Advanced Materials, via the Register

These diagrams from the Advanced Materials journal show stages of the Tsinghua University experiment, which is titled "Self-Fueled Biomimetic Liquid Metal Mollusk", including the insertion of the aluminum "fuel" (b) and movement/fusion of gallium alloy droplets (e).
 

Tsinghua University scientists led by Jing Liu, have discovered a 'smart' liquid metal alloy that moves on its own. The liquid metal is a mixture of gallium, indium and tin. It stays liquid at temperatures above -2 degrees Fahrenheit (-19 Celsius), can move itself in a circle, straight line, or even squeeze through complex shapes when placed in a sodium hydroxide solution.

Travelling Metal. Tsinghua University

This diagram details the journey of the liquid metal traveling around the inside edge of a petri dish filled with sodium hydroxide. Moving on its own power, it can navigate the inside circumference of the dish in less than 10 seconds.

Its integrated power source is a flake of aluminum embed in the liquid metal; the aluminum reacts with the sodium hydroxide to release hydrogen gas, while placing the aluminum in the liquid metal drop's rear creates differences in electrical charges across the liquid metal. The charge differences in differing parts of the liquid metal causes movement, as the liquid metal physically adjusts itself to balance out the resulting differences in internal pressure. Currently, a drop of liquid metal has enough power to move around for 30 minutes to an hour. Nanotechnology could be used to build the embedded control system, sensors and computers for any liquid metal robot.

A Little Electric Push. Tech Times

Certain gallium allows can undergo controlled shapeshifting once an electric charge in applied. It might be basic research now, but self healing metals would have a lot of civilian and military applications.

Liquid metal may be the first step in a new arms race. In 2014, both Tsinghua University and North Carolina State University discovered that applying electrical currents to gallium alloys (like the liquid metal) would allow for controlled shape-shifiting in the metal (though they still needed an external power source).

Squeeze In. Discovery News

The liquid metal has been observed to not just to move on its own, but also to squeeze into tight spaces as it moves forward (moving the aluminum component can change its direction).

Tsinghua's liquid metal is still a basic research project confined to the laboratories (not to mention vats of sodium hydroxide, until they discover a way for the liquid metal to react with the atmosphere). The liquid metal could be used to build self contained pumps that don't require outside power or batteries, saving on weight and complexity for items like night vision and laser cooling pumps. The ability of liquid metal with its own embedded power source could even one day be the basis to build self repairing armor on tanks and changing aircraft fuselages for fuel efficiency and speed.

T-1000. Terminator 2 Judgment Day

If you really wanted to build a robot like Skynet's T-1000 Terminator out of shapeshifting metal at room temperature (and we strongly advise against that), you'd need a substance like Tsinghua University's self powered liquid metal to avoid those embarrassing and inconvenient electrical cords.

More distantly, Liu hopes that his invention would one day be used to build shapeshifting robots to repair pipelines and delivery medicine inside blood vessels. But military engineers would also probably like to take a crack at turning liquid metal into shape shifting drones and robots, familiar to Terminator 2 fans as SkyNet's T-1000. This makes the project both exciting for the future of science and war, as well as a sign that John Connor probably should stay away from China in the future.
By Jeffrey Lin and P.W. Singer.  Popular Science

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