Rise of the liquid gallium smart robots

Skynet's liquid metal T-1000 robot seemed fantastical when the Terminator 2: Judgement Day movie was released in 1991. Fast forward 30 years, however, and researchers at the Chinese Academy of Sciences have created early renditions of shapeshifting soft robots made of liquid gallium infused with magnetic neodymium-iron-boron microparticles.

The "robot" is made up of magnetic pixels – particles containing a liquid metal and a neodymium magnet – as well as an elastic matrix made of silicon. By magnetizing each pixel individually through a process called laser-assisted heating, the researchers were able to devise a method of creating a magnetic soft robot that can be programmed.

"Whether they are based on soft or hard magnetic materials, the magnetization process of most soft robots is coupled with its manufacturing process," said Ran Zhao, one of the researchers who carried out the study. "In other words, the robots cannot realize the reconfiguration of functions through programs like traditional robots with control units. This means that magnetic soft robots have a long way to go before they can be applied in real-world settings."

Ultimately, the robot can only maintain a fixed shape, switching to its "rigid body" mode that has been preprogrammed based on magnetic polarization.

"By changing the temperature, we can repeatedly 'write' and 'erase' magnetization profiles as needed," Zhao explained. "Using our approach, we manufactured a reprogrammable magnetic soft robot. By changing the magnetization profile in the elastomer, the robot can produce different response actions."

The key principle behind this endeavor was to wrap the related magnetic particles in phase transition materials – a study of materials that releases or absorbs energy as it changes; and a quickly growing discipline in recent months due to breakthroughs and innovations in materials science, in an effort to reduce carbon emissions.

"The response actions and functions of our soft robot can be reconfigured by programming," said Zhao. "We can use a single pixel or multiple pixels as an independent magnetization profile; thus, the scale of our robot can span across a large range. By adding flexure hinges between magnetic pixels, we make the soft robot have a unique hardening function."

In the future, this magnetic coding technique could be used to create more than just soft magnetic robots as we continue to explore quantum mechanics and its capabilities of creating technologies with the very building blocks of our universe.

"The technique we created allows our magnetic soft robot to reconfigure its functions and switch freely between soft form and rigid form, so as to meet the needs of different tasks," Zhao said. "The magnetic soft robot has a certain 'intelligence,' thus the range of tasks it can execute has been greatly increased."

The research team's work highlights the feasibility of manufacturing magnetic, reusable soft robots on a large scale. In particular, these robots could be useful for environmental monitoring, drug transport, and in vivo sampling applications.

"As a next step, we will further reduce the size of the robot and try to design a 3D structure," Zhao added. "We believe that the development of universal technology will help to make the micro magnetic soft robot from laboratory to commercial application as soon as possible."