New magnetic separation technique might detect multiple pathoge...(hieve effectively infinite separation be...)

While the researchers know how to precisely control which particles move and which stay put, by varying the frequency of the magnetic field they apply, the underlying physics responsible for the behavior remains partly unexplained and will be the subject of future investigation, Yellen said.

Micrometer and nanometer sized "superparamagnetic" beads already are used widely to magnetically separate biological molecules and cells from complex fluid mixtures, Yellen said. Superparamagnetism is a form of magnetic behavior which occurs primarily in materials composed of very small magnetic grains. Such materials are commonly used for drug delivery and imaging applications and in biomedical devices because they become magnetized only in the presence of an externally applied magnetic field, which helps prevent clumping.

Over the past few decades, however, there have been few new developments in the field of magnetic separation, according to the researchers, with most of the efforts focused on using stronger and stronger magnetic fields and field gradients.

"Now, we've demonstrated a fundamentally new and different approach to magnetic separation, which can dramatically increase the separation efficiency, not by exploiting stronger fields and field gradients, but rather by precisely tuning the mobility of beads and exploiting the non-linear dynamics of particles moving in a traveling wave," Yellen said.

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