Improving the Design of a Magnetic Nanoparticle Separation Channel

Science Center, Bent Corridor

Magnetic nanoparticles are of much importance in applied fields such as biomedicine and data storage. To maximize efficiency in these applications, we are developing a method to sort nanoparticles for uniform magnetic properties. Our proposed separation method uses an inverted linear Halbach array, which consists of 47 modulating neodymium iron boride permanent magnets. Unconventionally, the low-flux side is used as it provides a region of low magnetic field, yet high magnetic field gradient that will allow selective clustering of particles. A flow channel suspended at an appropriate distance above the array allows higher moment particles to aggregate and accumulate on the bottom of the channel, while lower moment particles flow out of the channel as filtrate, without chaining and falling. Methods, such as vibrating sample magnetometry, transmission electron microscopy, and x-ray diffraction, are used characterize the samples before and after separations. A new channel has been designed to accommodate samples suspended in organic solvents, as the magnetic nanoparticles are typically synthesized in ether solutions. This summer, we successfully tested and optimized the prototype for the new channel to ensure leak-tight, visible, and reproducible operation.