Tiny robots made of metallic powder stuck to plastic tape and controlled by magnetic fields could one day crawl inside internal organs and repair injuries
Robots made from sticky tape and dust can morph into various shapes under the direction of a magnetic field. They may one day be able to crawl into computers to fix broken circuits or even inside the human stomach to apply therapeutic patches to gastric ulcers.
Soft robots that have no batteries, motors or electronics and that are powered and controlled from a distance by light or magnets are a popular field of research. But there are barriers to overcome before they can be used in practical applications, including the need for a cheap manufacturing process.
Zhang Li at the Chinese University of Hong Kong and his colleagues discovered that a magnet-controlled robot can be created easily and at low cost using sticky tape onto which non-sticky wax has been printed in a specific pattern. When powder containing microparticles of magnetic neodymium-iron-boron is applied to the tape, it sticks to the exposed sections but not to the wax overlay – a little like a stencil. The wax is then dissolved in ethyl acetate solution to leave an accurately shaped magnetic robot.
Zhang says that the process could be easily automated and that tiny robots could eventually be printed in long rolls, just like newspapers coming off a printing press.
In experiments, his team created sticky tape robots of various shapes around a centimetre across that change their geometry depending on the presence and orientation of a magnetic field. Some of the robots were able to move through water or along flat surfaces, and one device was able to crawl across the surface of pig stomach tissue in the lab and place a small therapeutic patch onto a gastric ulcer before detaching from the patch and moving away.
Zhang says that these devices could be used in the future to deliver drugs or carry out simple medical procedures in the stomach or intestines. “It can be deployed in this kind of folded, small scale, and when it reaches a large cavity it can open up,” he says. “It’s very much like a satellite, where after its launch into outer space the solar panels will open up. So when you swallow this device, it should have a very small size.”
There are hurdles to overcome prior to clinical trials, however. “The first thing is safety, because currently we’re using a very strong magnet called a neodymium-iron-boron magnet. It’s actually not that safe,” says Zhang. “It’s kind of toxic to the cells.”
Journal reference: Science Advances, DOI: DOI: 10.1126/sciadv.abn8932
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