When exposed to the flipping magnetic field, the particles flipped as well and started to roll. In the experiments, the vortices were allowed to move freely in the water matrix, where researchers studied their natural behavior. Within the single magnetic field, the rollers lined up as if they were indeed part of a compass needle, but when exposed to a magnetic field that changed orientation 60 times a second, the rollers instead flocked together and formed vortices. "And we use a magnetic field to transfer energy." "Each particle is like a small compass," Snezhko explained. In their first series of tests, researchers put about 100 miniscule magnetic nickel rollers, or spheres, in a water matrix exposed to a single axis magnetic field, followed by an alternating magnetic field. The pair published recent findings in the June 14 issue of Nature Communications. "We are doing this as a search for a new kind of active material. "Transporting objects is a far reaching goal, but we're working on the first steps, which is to understand the basic principles," Snezhko said.
By exposing groups of microscopic metal magnetic rollers to various magnetic fields, Argonne physicist Alexey Snezhko and postdoc Gasper Kokot are creating their own vortices to accelerate that understanding. The vortices could one day be used in lab-on-a-chip designs to move particles, like blood cells, from one place to another, or to build materials with self-healing properties.īefore they can harness the tiny vortices, though, scientists need to understand how their components, or colloidal particles, form and function.
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