Mag-Guider: permanent magnet systems to steer and image superparamagnetic
A new concept of using permanent magnet systems for guiding superparamagnetic nano-particles (SPP) on arbitrary trajectories over a large volume is presented. The same instrument can also be used for magnetic resonance imaging (MRI) using the inherent contrast of the SPP [1]. The basic idea is to use one magnet system, which provides a strong, homogeneous, dipolar magnetic field to magnetize and orient the particles, and a second constantly graded, quadrupolar field, superimposed on the first, to generate a force on the oriented particles. As a result, particles are guided with constant force and in a single direction over the entire volume. Prototypes of various sizes were constructed to demonstrate the principle in two dimensions on several nanoparticles, which were moved along a rough square by manual adjustment of the force angle [1]. Surprisingly even SPP with sizes < 100 nm could be moved with speeds exceeding 10 mm/s due to reversible agglomeration, for which a first hydrodynamic model is presented. Furthermore, a more advanced system with two quadrupoles is presented which allows canceling the force, hence stopping the SPP and moving them around sharp edges. Additionally, this system also allows for MRI and some first experiments are presented. Recently this concept was combined with liquid crystalline elastomers with incorporated SPP to create “micro-robots” whose coarse maneuvers are performed by a MagGuider-system while there microscopic actuation is controlled either by light or temperature [2]. 1. O. Baun, PB, JMMM 439 (2017) 294-304. doi: 10.1016/j.jmmm.2017.05.001 2. D. Ditter, PB et al. Adv. Functional Mater. 1902454 (2019) doi: 10.1002/adfm.201902454
Speaker Biography
Peter Blümler (Institute of Physics, University of Mainz)
Peter Blümler studied chemistry and medicine at the Johannes-Gutenberg University of Mainz and obtained his diploma in chemistry in 1990. He then joined the group of Prof. Spiess at the Max-Planck institute for polymer research for his Ph.D. studies, and completed in 1993 his dissertation on the modification and appli¬cation of NMR imaging sequences to problems in materials science. After one year of postdoctoral studies at IBM Almaden Research Labs in San Jose, he took a senior staff position in the group of Prof. B. Blümich at the RWTH Aachen. Together with Prof. Blümich, he was one of the pioneers of the new technology of mobile, low field NMR-devices (NMR-MOUSE), which are now well-established analytic tools in materials research and cultural heritage. In 1999 he was appointed senior lecturer of physics at the University of Kent at Canterbury. For personal reasons, he decided to move back to Germany in 2001 and rejoined the group of Prof. Spiess as a project leader to develop new MRI methods for applications in medicine and materials science, with a special focus on hyperpolarized gases. In 2004, he was headhunted by Prof. Ulrich Schurr, Research Center in Jülich, to set up a high- and low-field NMR-lab specialized on studies of plants. In his function as a manager of the technical division, he also developed new instruments for MRI, PET and microwave applications for plant studies. Since 2009 he is a senior scientist at the institute of physics at the University of Mainz, where his research is focussed on hyperpolarized gases and ultra-precise magnetometry for fundamental experiments.