Ferrofluids – those distinctively spiky liquids – are made up of magnetically sensitive nanoparticles in a carrier liquid, and although they respond to applied magnetic fields, they retain no magnetism outside of that field. But researchers have now succeeded in making actual liquid magnets. Shown above, these drops also contain ferromagnetic nanoparticles. But unlike traditional ferrofluids, in these drops the nanoparticles are not entirely free to move. They’re jammed together at the interface, so when a magnetic field is applied, the nanoparticles will align like tiny bar magnets. When that magnetic field is removed, though, the nanoparticles cannot easily reconfigure, so they remain aligned and the drops continue being magnetic.
Researchers hope these ultrasoft magnets, which can be manipulated remotely through magnetic fields, will be useful in the future for applications like targeted drug delivery. In theory one could introduce, say, chemotherapy drugs into one of these liquid magnets, then use magnetic fields to guide it directly to a cancerous tumor. (Image and research credit: X. Liu et al.; via Science News; submitted by Kam-Yung Soh)