Scientists have seemingly discovered a way to turn water droplets into permanent magnets that appear to have a new form of magnetism never seen before. The study, recently published in the Science journal details the extraordinary, accidental, discovery that the scientists now believe has the potential to revolutionise a huge range of fields from robotics to the way medicines are administered.
The key role magnets play in the latest technology in the world often flies under the radar but they are an essential component to electronics and motors. They are often also present in medical devices. They are all, though, solid matter and mostly made of metal with the exception of ‘plastic magnets’ which are sometimes used in computer hardware and made of organic polymer. The closest thing to a liquid magnet is ferrofluids that contain iron particles and respond to magnets. But they need to be within a magnetic field. If that’s removed they lose their magnetism.
But a chance discovery has led scientists at the Beijing University of Chemical Technology to the understanding that adding iron oxide nanoparticles to water means they can create permanent magnets out of water droplets. The ‘serendipitous’ moment, as explained by Professor Tom Russell who works at the university, while also being affiliated to the Lawrence Berkeley National Laboratory in California, came from experiments his colleague Xubo Liu was conducting on droplets of water that contained iron particles and were suspended in oil. He noticed the iron particles would be drawn to the surface of the droplets when he added a surfactant, which is similar to detergent. The particles then drew together, forming a metal crust.
As would be expected, exposing the droplets to a magnetic field saw the iron crusts drawn towards it. But in contrast to what the scientists expected, when the magnetic field was removed, the droplets pulled together. They had retained their magnetic state and, described Professor Russell “span in beautiful concert”. Not only did the droplets retain permanent magnetism but they held their shape when squeezed.
“We almost couldn’t believe it. Before our study, people always assumed that permanent magnets could only be made from solids.”
The magnet droplets displayed another bizarre quality. Not all of the iron nanoparticle in each droplet were drawn into the crust at the top. The remainder stayed suspended in the water as particles. But they were also magnetic and acted as extensions to the same magnet. Still free to move within the water, this defies current understanding of how magnets works with no obvious explanation.
“I’m certain magnetics people will tell me I’m crazy. That’s all right. Data is data; I believe data. I can’t do anything else.”
Despite the fact the scientists do not yet fully understand why their experiment showed the results it did, they see some obvious applications for liquid magnets such as to control flexible robotics used to deliver targeted medicines inside a body.
“We can 3D print a little person and put little magnetic parts at the ends of the arms. Conceivably we could have this liquibot grabbing things. I can put drugs in the droplet. Because it’s a magnet, it can be controlled and moved. I can deliver that cargo. Can we do that in a body? Sure.”
Commenting on the discovery but not involved in it, Rémi Dreyfus, from the University of Pennsylvania, has stated that the results challenge established physics and could have applications we aren’t yet able to fully conceive:
“not only opening up new perspectives in direct applications of their material, but also enabling a cascade of innovations that have not yet been imagined”.
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