Three permanently magnetized liquid droplets floating in oil. As they spin in response to a rotating magnetic field, their activity wraps orange dye around themselves. (X. LIU ET AL/SCIENCE 2019)
Some liquids contain particles that can become magnetized when placed in a magnetic field. However, the orientation of their magnetic poles tends to get jumbled as soon as the magnetic field goes away. At this point, the liquid no longer is magnetic.
Thomas Russell, a polymer scientist, and his colleagues added certain polymers to the droplets’ recipe which allowed them to make permanently magnetized droplets. Such magnetic drops could be used to build soft robots. They might also be used in ingested capsules that doctors could use to direct the medicine to targeted cells.
Read more about liquid reconfigurable ferromagnetic materials here.