Optimal realization of arbitrary forces in a magnetic stereotaxis system

Abstract

Very small implanted permanent magnets guided by large electromagnetic coils have been proposed previously as a method for delivering hyperthermia to or guiding catheters through brain tissue. This procedure is termed "magnetic stereotaxis." Early efforts employed a single coil on a movable boom, a design that proved logistically difficult to use on human patients. The present work deals instead with a design where several stationary coils are employed to develop a force on the implanted magnet. The coil current-to-force relationship is developed for this type of machine, and several optimal solutions for realizing an arbitrary static force are presented for various constraints on the orientation of the implanted permanent magnet. Costs of the different solutions are compared in several examples using a mathematical model based on the Magnetic Stereotaxis System (MSS) developed by Stereotaxis, Inc.,

MRI-based communication for untethered intelligent medical microrobots

“…Yesin et al [72] studied an idea in which an untethered microrobot is steered inside body fluids while a pair of coils developed a gradient field and superimposed a uniform field of another pair of electromagnetic coils. Meeker et al [73] complement the work of Gardi and used several stationary coils instead of one to develop a force on the implanted magnet. In a recent work, Steager et al [74] presented a magnetically actuated microrobot to automatically manipulate cells and microbeads.…”

Sensors for Catheter Applications

“…By successive movements and heating, the tumor can be destroyed with little damage to the surrounding tissue [64]. Alternatively, the magnetic seed could be used to guide the tip of a catheter, for example to deliver drugs directly to sites inside the brain [65,66]. Other studies were oriented towards brain biopsy procedures [67].…”

“…The fundamental methodology employed by this system is called magnetic stereotaxis [63] and it implies the use of large electromagnetic coils, which guide a magnetic seed (a small piece of implanted permanent magnetic material) along a selected trajectory through the human body. To reduce incidental damage, the trajectory is defined preoperatively, using x-ray or MRI scans, by selecting a path that avoids important anatomical structures.…”

Adaptive Controller and Observer for a Magnetic Microrobot

“…Thereby, they result in lessened medical side effects and a better therapeutic efficiency and safety. Magnetically-deflected catheters [1], [2], [3] solve some weaknesses induced by conventional catether-based techniques, like the lack of manoeuvrability and resulting vascular injuries. So as to both improve accessibility to hard-to-reach body areas and reduce the risk of infection, another approach relies on untethered microrobots.…”