This New Liquid is Magnetic, and Mesmerizing
Lodestone, a naturally-occurring iron oxide, was the primary persistently magnetic materials identified to people. The Han Chinese used it for divining boards 2,200 years in the past; historic Greeks puzzled over why iron was drawn to it; and, Arab retailers positioned it in bowls of water to observe the magnet level the best way to Mecca. In trendy instances, scientists have used magnets to learn and report knowledge on onerous drives and kind detailed photos of bones, cells and even atoms.
Throughout this historical past, one factor has remained fixed: Our magnets have been produced from strong supplies. But what if scientists might make magnetic units out of liquids?
In a examine printed Thursday in Science, researchers managed to do precisely that.
“We’ve made a new material that has all the characteristics of an ordinary magnet, but we can change its shape, and conform it to different applications because it is a liquid,” stated Thomas Russell, a polymer scientist on the University of Massachusetts, Amherst, and the examine’s lead writer. “It’s very unique.”
Using a particular 3D printer, Dr. Russell and his colleagues on the Lawrence Berkeley National Laboratory injected iron oxide nanoparticles into millimeter-scale droplets of toluene, a colorless liquid that doesn’t dissolve in water. The staff additionally added a soap-like materials to the droplets, after which suspended them in water.
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The soap-like materials prompted the iron oxide nanoparticles to crowd collectively on the floor of the droplets and kind a semisolid shell. “The particles get stuck in place, like a traffic jam at 5 o’clock,” Dr. Russell stated.
Next, the scientists positioned the droplets on a stirring plate with a spinning bar magnet, and noticed one thing extraordinary: The strong magnet prompted the constructive and adverse poles of the liquid magnets to comply with the exterior magnetic discipline, making the droplets dance on the plate. When the strong magnet was eliminated, the droplets remained magnetized.
“We almost couldn’t believe it,” Dr. Russell stated.
In the 1960s, scientists at NASA found that some liquids might turn out to be magnetized within the presence of a robust magnetic discipline. But these liquids, often known as ferrofluids, at all times misplaced their magnetism as quickly because the stronger, exterior magnetic discipline was eliminated.
In distinction, the droplets created by Dr. Russell and his staff turn out to be magnetic and keep that means, because of the nanoparticle shell that varieties throughout the soapy emulsion.
As a end result, the droplets may be made to alter form with only a small utility of drive, as if a visitors cop stumbled on that rush-hour visitors jam and began transferring issues alongside, Dr. Russell stated.
The movement of liquid droplets may also be guided with exterior magnets. Thus employed, liquid magnets could possibly be helpful for delivering medication to particular places in an individual’s physique, and for creating “soft” robots that may transfer, change form or seize issues.
“We hope these findings will enable people to step back and think of new applications for liquid magnets,” Dr. Russell stated. “Because until now, people in material sciences haven’t thought this was possible at all.”