Navigation of superparamagnetic particles with a pre-magnetized high-temperature superconducting bulk in a weak background field

Abstract

Recent research has shown significant progress towards a full-body
magnetic drug delivery (MDD) system for use in targeted cancer treatments.
Although many different MDD systems have been proposed to generate strong
remote forces capable of rapidly changing directions at distances greater than
10 cm, current state-of-the-art technologies lack in force strength and/or degrees
of freedom. Knowing that high temperature superconducting (HTS) bulks can
achieve trapped fields an order of magnitude larger than ferromagnets, this work
aims at numerically and experimentally evaluating the forces that can be produced
by HTS bulks in a uniform magnetic field. We first use Hall probe measurements
and finite element simulations to determine the magnetic field generated by an
HTS pellet and show that both results are in good agreement. Using a combination
of simulations and experiments, we then show that for a 14.6 mm YBa2Cu3O7-x
pellet magnetized at 2 T, remote forces on superparamagnetic microparticles
are maximized at background fields of ~50 mT. In addition, the direction of the
magnetic forces can be flipped by changing the direction of the applied field relative
to the HTS's magnetization. The HTS bulk was successfully used to navigate
magnetic microparticles in a glass bifurcation mimicking the hepatic artery of the
human liver. Finally, we show by simulation that a large HTS pellet magnetized
at 5 T in a field of ~250 mT can generate stronger forces with more degrees of
freedom than the strongest forces achievable in current MDD technologies.