High-powered and high-frequency magnetic field generation and control methodology for biomedical magnetic robots

Abstract

Magnetic robots, i.e., robots composed of magnetic materials, have been widely investigated for various biomedical applications ranging from biological molecule manipulation to medical treatment of the human body. In particular, medical magnetic robots are promising alternatives to conventional surgical procedures, because surgeons can wirelessly and precisely conduct various tasks within the body, such as drug delivery, tissue biopsy, stent deployment, enhanced unclogging, etc. In addition, wireless manipulation ensures surgeons and other medical staff are not exposed to radiation generated from imaging devices such as x-rays. This dissertation has three major outcomes. 1.Reviewed the relevant background regarding the definition, advantages, applications, actuation methods, and scale effects for biomedical magnetic robots. In particular, the various actuation methods utilizing magnetic torque and force are classified in three types, and scale effects for magnetic torque and force actuation are compared utilizing similar coil systems and magnetic robots. 2.Developed a high-frequency magnetic field generation method based on RLC circuit resonance (circuit includes resistor (R), inductor (L), and capacitor (C), in series). The proposed RLC circuit effectively compensates for magnetic navigation system (MNS) inductance via the variable capacitor at resonant frequency. The resonant frequency can also be modified by adjusting the capacitance. The proposed RLC circuit was constructed following conventional MNS, utilizing three orthogonal coils, and experimentally verified by measuring current, phase, and magnetic field at several resonant frequencies. The circuit’s effectiveness was also demonstrated by controlling the helical robot to move in bifurcated tubular environments and unclog a clogged area. 3.Developed a method to generate a high-powered magnetic field utilizing a closed magnetic circuit (CMC), with a closed-circuit magnetic navigation system (CMNS) to prevent magnetic flux leakage from the back-side of the MNS. The CMNS combines four individual CMCs, and the complete design procedure is also included in this thesis. A magnetic field mapping method based on finite elements approach was also developed to precisely control the magnetic field in real-time. The constructed CMNS was verified experimentally to have superior steering capability for commercial magnetic catheters than other MNSs.