Pumping Fluid With No Moving Parts

RogerRoast writes "In a study published in Physical Review B (abstract; full version is paywalled), researchers demonstrate for the first time an approach that allows ferrofluids to be pumped by magnetic fields alone. The invention could lead to new applications for this mysterious material. Though numerous industrial, commercial, and biomedical applications for ferrofluids have since been created, the original goal — to pump liquids with no machinery — remained elusive, until now. The ferrohydrodynamic pump method works when electrodes wound around a pipe force magnetic nanoparticles within the ferrofluids to rotate at varying speeds. Those particles closest to the electrodes spin faster, and it is this spatial variation in rotation speed that propels the ferrofluid forward."

Comments

Re:Interesting to see a macro-scale solution

[manicb]

(Sorry for gloating, I *finally* got access to journals again and it is SO EXCITING. I have no life.)

Right, according to the article, the reason people have looked at ferrofluids for microfluidics is that they were interested in using a thin layer of ferrofluid to drive a plug of other liquid. This would be analogous to the ionic double-layer (Debye layer) in electro-osmosis, as mentioned above. In this experiment, they use only ferrofluid (with a dash of a tracer) and seem to achieve a funky toroidal region, leading to ordinary laminar flow. If they excited it in more places then they could have a lot of mixing, which would be great for a cooling system.