Magnetic manipulation instrumentation for medical physics research

Abstract

The noncontact magnetic manipulation of probe masses within the body is an area of research that has received substantial attention from the medical physics community, especially during the past three decades. The therapeutic and diagnostic possibilities arising from such technology include site-specific drug delivery within the central nervous system, advancement of techniques for navigation and selective catheterization of vessels within the cardiovascular and cerebrovascular systems, and the nonsurgical exploration of the alimentary and respiratory tracts. In this review, we examine the physical principles underlying in vivo magnetic manipulation systems, and catalog the various types of instrumentation used for such purposes to date. Thereafter, we evaluate the different methods of image-based localization used to identify the position of the probe within the body. Finally, we appraise an emerging technology known as nonlinear magnetic stereotaxis, a technique that permits minimally invasive access to difficult-to-approach parts of the brain. We close the review with a few comments on the directions for future work within this field.

MRI-Guided Nanorobotic Systems for Therapeutic and Diagnostic Applications

“…For this purpose, several groups have been studying and developing magnetic micro/nanoparticles (14)(15)(16)(17) and have designed techniques for their controlled locomotion from an initial point to a desired final point in the vasculature. The research in this field was initiated in the early 2000 and initially focused on guided magnetic microparticles captured by a static magnetic fields generated by magnets (18)(19)(20) or superconducting magnets (21), (22). In these studies the particles were simply attracted towards the targeted region without any tracking and feedback mechanism.…”

Field-induced self-assembled ferrofluid aggregation in pulsatile flow

“…Again, for these applications, the magnetic nanoparticles are influenced by magnetic fields generated outside the human body that produce the desired transport characteristics. 14 While the physical principles underlying the design of the magnetic manipulation devices are challenging, a proper understanding of ferrohydrodynamics and particle transport and dispersion is a necessary first step to localize the ferrofluid nanoparticles at a target location. In particular, the retention time of an aggregate of appropriate size and concentration before it is washed away from a targeted location ͑e.g., by a pulsatile blood flow, or by the buffer fluid in a microchannel͒ is an important parameter to characterize sufficient functional activity of the nanoparticles ͑e.g., drug desorption in case of MDT or the action of chemical etching in case of microfabrication͒.…”

Mini and Micro Propulsion for Medical Swimmers

“…The non-contact magnetic field actuation also draws a lot of attention to the micro robot propulsion with a possible application to in vivo drug delivery, nonsurgical exploration and navigation [52]. For instance, a spiral-type micro robot was designed by Ishiyama et al [53], which mimicked the cilium propulsion of natural bacteria.…”