What is the dream material 'liquid metal' like Terminator 2 T-1000?


David Kutschke

If you hear a robot that uses liquid metal, many people will think of the T-1000 that appears in the movie ' Terminator 2 '. However, there is talk about the prospect that soft robots and wearable computers will be realized, not actually murder robots.

Core Concept: Liquid metal renaissance points to wearables, soft robots, and new materials | PNAS

'Most researchers are unaware of the unique properties and uses of rare materials, which are liquid at room temperature to transfer heat and electricity, like other metals. In the past few years, research on liquid metals has led to the Renaissance It's a change that should be called, 'said Michael Dickie, an engineering researcher at North Carolina State University. He has previously been able to output liquid alloys from 3D printers.

Liquid metal like T-1000 of Terminator 2 can be output with 3D printer-gigazine

Mercury is the most commonly imaged liquid metal, but Dicky's attention is on gallium, a metal that is almost harmless unlike mercury. Gallium does not evaporate and cause inhalation accidents, and has a low melting point of about 30 degrees. Also, when mixed with tin or indium , it changes into a useful alloy with a lower melting point.

Liquid metal, mainly gallium, is not only flexible but also has properties as an electrical conductor, so it is mainly intended to be used as a material for soft machines. In 2019, a research team from Liang Hu et al. Of Peking University's Faculty of Engineering also developed a magnetic liquid metal droplet (MLMD) that can move three-dimensionally by itself using magnetic control.

The details of the MLMD developed by Hu et al. Can be understood in one shot by reading the following article.

Successful development of liquid metal that moves not only horizontally but also vertically like `` Terminator 2 '' T-1000-gigazine

The key to controlling such liquid metals, according to Dickie, is the ability to form an ' oxide film ' when exposed to air. Most metals, including liquid metals, form an oxide film when exposed to oxygen in the air, but liquid metals form a nanometer-thick film on the surface and retain the liquid metal inside It acts like skin. Thanks to that, liquid metal does not spill like water or soak into cloth, it can be bent and stretched, stretched like paint, and can be shaped as desired with a 3D printer .

Furthermore, Dicky also found that if an alloy of gallium and indium was put in a strong alkaline liquid and a voltage was applied , the liquid metal, which had been spherical due to surface tension, could be shaped like a snow crystal. Was . The usefulness of this property is unknown, but if the surface tension of the film can be controlled, the development of electronic and optical devices that can reconfigure the shape can be expected.

by Minyung Song

In fact, Dickie and his colleagues at North Carolina State University

have successfully developed a 'reversibly deformable, mechanically tunable fluid antenna.' Gallium alloy wrapped in flexible plastic, this antenna can be extended up to 10 times its original length, and has the property of being easily connected even if cut.

by Michael Dickey

Dicky and colleagues have also succeeded in creating a plastic electronic circuit by sandwiching nanoparticles made of an alloy of gallium and indium with rubber. By tracing the board with a pen, it is possible to 'handwrite' any electronic circuit. Associate professor Martin Thuo, a materials engineering researcher at Iowa State University, has also developed electronic circuits printed on chunks of gelatin and rose petals.

Thuo uses this technology to create 'soft electronic circuits that can be embedded in the brain.' Already, deep brain stimulation , which treats Parkinson's disease and depression by implanting metal electrodes in the head, has been put to practical use.However, if liquid metal is soft and easy to change shape, safer and easier surgery is possible. You can do this treatment with:

Liquid metals that can make soft electronic circuits are expected to work as sensors and actuators for soft robots in the future. Soft materials, such as rubber and resin, generally conduct very little electricity or heat, because both liquid metals can conduct very efficiently. Carmel Magidi, who studies mechanical engineering at Carnegie Mellon University, also developed a material that bends when electricity is applied by injecting liquid metal into a soft elastomer . With this, artificial muscle is realized.

On the other hand, attempts have been made to use it in fields other than robots. For example, filters that can filter water contaminated with heavy metals and oils, and catalysts that decompose atmospheric carbon dioxide with low energy consumption.

Although catalysts with similar functions have already been developed, liquid metals can form small droplets and promote reactions outside the surface, so conventional catalysts using solid metals He says that he can react more efficiently.

Regarding the new technologies enabled by these liquid metals, Dicky says, 'There is more than a technical problem: it is not widely accepted that liquid metals are not only attractive, but potentially useful. That is, most of the challenges are just consciousness issues, 'he said, encouraging the widespread adoption of liquid metals and the potential for a variety of technological innovations.

in Hardware, Posted by log1l_ks