CAREER: Design, Optimization, and Feedback Control of Noncontact Magnetic Manipulators

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Many medical procedures are invasive in nature when the physicians need to access internal organs of a patient. Since these procedures are usually inconvenient, painful, and costly, significant research efforts are being conducted on development of noninvasive medical tools and techniques. Any effort in this direction has to answer a fundamental question: how to operate a medical tool without actually touching it. A viable answer to this question is the use of magnets: magnetized tools can be safely operated inside a patient's body using sufficiently strong magnets located outside the body. For example, one can imagine a painless, anesthesia-free gastrointestinal endoscopy procedure that utilizes a miniaturized camera carried by a magnetized tiny capsule, and the capsule is navigated inside the gastrointestinal tract by a set of external magnets. This set of magnets, together with the machinery controlling them, is generically called noncontact magnetic manipulator.The purpose of this project is to establish a technical foundation for design, implementation, and evaluation of noncontact magnetic manipulators suited for a wide range of surgical, medical imaging, and diagnostic applications. The results of this research will support the efforts of many researchers, engineers, physicians, and private companies currently working on design and development of noninvasive medical devices, and therefore, will contribute to a broader effort in development of novel medical techniques which improve the quality of care, patient safety, and access to affordable health care. Furthermore, this project will advance the development of miniaturized noncontact magnetic manipulators, which are essential for actuation and control of micro- and nano-scale systems widely used in biomedical and nanotechnology applications.Noncontact magnetic manipulators utilize arrays of multiple magnets to generate and precisely control magnetic fields, which interact with magnetic objects or fluids in their region of influence in order to manipulate them from a distance without direct mechanical contact. Since magnetic fields propagate unchanged through nonmagnetic barriers, noncontact magnetic manipulators provide a unique capability to control magnetic objects in the regions behind such physical barriers, which are otherwise inaccessible. The focus of this project will be on permanent magnet manipulators in which magnetic fields are controlled by mechanical movement of permanent magnets, rather than the conventional approach relying on electromagnets and easy control of their terminal voltages. This conventional approach has been the focus of much of the existing literature on magnetic manipulators. However, permanent magnets produce much stronger magnetic fields than electromagnets of the same size, weight, and cost. This key advantage advocates a technological paradigm shift toward permanent magnets as a necessary step in development of compact, effective, and inexpensive magnetic manipulators for medical applications which often require larger magnetic forces at further distances. The existing literature on permanent magnet manipulators is still at an early stage and inadequate to support the development of cutting-edge technologies for a broad range of novel applications. The proposed research is aimed at filling this void by establishing a framework for design, analysis, optimization, and feedback control of permanent magnet manipulators. This framework consists of mathematical modeling tools supported by experiment, real-time optimization methods, and feedback control techniques for several scenarios of practical importance. These scenarios include path tracking of single or multiple magnetic particles, multi-degree-of-freedom motion control of magnetic rigid bodies, and transport of magnetic fluids. This coherent set of analytical and numerical tools will promote advancements in design and manufacturing of precise, reliable, compact, and cost-effective magnetic manipulators suitable for integration into new generations of medical devices, as well as micro- and nano-scale systems.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.