Scientists invented a melting liquid robot that can escape from a cage
The Washington Post January 27, 2023
The metal microbot, made out of liquid metal microparticles that can be steered and reshaped by external magnetic fields, has been widely compared to the character T-1000 in "The Terminator" movie franchise, a cyborg assassin played by Robert Patrick that could morph his way around solid objects before embarking on a murderous rampage.
But, in contrast with the film, the inventors of this robot believe their discovery can be used for good — particularly in clinical and mechanical settings — by reaching hard-to-reach spaces.
The robot was presented as part of a study into the metal microparticles, known as a type of magnetoactive phase transitional matter, that can morph shape, move quickly, be controlled easily and carry many times its own body weight.
The scientists behind the study, who published their findings Wednesday in the journal Matter, created the robot using a composite of metals with a low melting point.
"This material can achieve Terminator-2 like performance, including fast movement and heavy load bearing when it is in its solid state, and shape changing in its liquid state," Chengfeng Pan, an engineer at the Chinese University of Hong Kong who co-authored the study, told The Washington Post, when asked about his discovery and the comparisons being made to the Terminator movies.
"Potentially, this material system can be used for applications in flexible electronics, health care, and robotics."
By blasting the robot with magnetic fields at alternating currents, scientists increased its temperature to 95 Fahrenheit and caused it to morph from a solid into a liquid state in 1 minute 20 seconds. Once transformed into liquid metal, the figurine could be steered through the narrow gaps of its locked cage by more magnets — demonstrating its morphability.
It is the first time a material capable of both shifting shape and carrying heavy loads has been identified for use in microbots, according to scientists at the Chinese, Hong Kong and American universities who worked on the study — solving a riddle that has confounded miniature robot makers who previously struggled to achieve both morphability and strength in their designs.
In its liquid form, the robot could be made to elongate, divide, and merge. In solid form, it was steered at speeds exceeding 3 mph and carried heavy objects up to 30 times its own weight. The combination means a robot made from the material could be deployed to fix electronics in difficult to reach places, for example working as a makeshift screw or for electronic soldering in tight spots.
In another experiment, researchers demonstrated how the robot could be deployed inside a model human stomach to remove an unwanted foreign object. Scientists steered the solid-form robot, measuring less than 0.4 inch in width, through the fake organ until it had located the foreign object. It was then melted by remotely controlled magnetic fields, stretched in its new liquid metal state around the object — and once securely hugging it — cooled back into a solid, allowing it to tow the foreign object out of the chamber.
The shape-shifting material is the latest in a string of developments across the burgeoning field of miniature robotics — as scientists race to identify potential medical and mechanical applications for tiny robots in everyday life.
Recent microrobotic innovations include robots small enough to potentially crawl through human arteries, intelligent enough to be taught to swim, and others capable of flying through the air powered by tiny onboard power supplies.
"We're still early in the exploration of what kind of materials can do this," Brad Nelson, a professor of Robotics at ETH Zurich who was not part of the study, told The Washington Post. One of the most interesting areas of research in microrobotics right now is in clinical applications — particularly the delivery of drugs to the brain or for treating blood clots, he adds.
While the metal microbot unveiled on Wednesday is instructive, its use of neodymium iron boron — toxic to humans — means it would only be clinically safe for use inside humans if it were completely removed from the body afterward, Nelson says.
"The folks that are really looking at clinical applications of these devices, we want to look at materials that can degrade in the body, remain in the body, without causing harm to the patient," Nelson said.
For Pan, the comparisons between his creation and the Terminator's T-1000 character are understandable — but limited in how far they can be taken. "Our robot still needs an external heater for melting and external magnetic field for controlling the movement and shape changing," he said. "Terminator is fully autonomous."
Nelson also argues that the risk of inadvertently creating a real-life cyborg assassin is not something to worry about.
"I don't see any possibility of injecting something into somebody, and then the microbots swim into their brain and take over their thoughts, or something crazy like that.
"The technology isn't there, and I don't see it going there," Nelson says — adding that were the technology to be tested in clinical settings there would be safeguards in place to protect against such risks.
The Washington Post's Naomi Schanen contributed to this report.