Magnetic Field Induced Concentration Gradients In Magnetic Nanoparticle Suspensions: Theory And Experiment

An approach for studying steady- state nanoparticle concentration gradients arising in magnetic nanoparticle suspensions in response to strong magnetic field gradient is presented. The experimental approach makes use of microscopic optical absorption measurements of ferrofluid interacting with arrays of patterned magnets. Experimental results are found to be consistent with a simple theoretical description that predicts the local nanoparticle concentration over a wide range of magnetic field conditions and ferrofluid volume fractions. (C) 2008 American Institute of Physics.