Effects of Dipole Model for Magnetic Induction on Biomedical Devices

Department of Mechanical EngineeringMagnetic field has been utilized in the biomedical applications for numerous decades, owing to contactless, noninvasive and harmless property, low cost and robustness in operation, and increased safety compared to other radiative fields. The medical applications using magnetic field have been investigated to enhance their performance. Such applications require accurate analysis of the magnetic field for improvement. However, it is difficult to compute the time-varying magnetic field, due to nonlinearity and interactions by various electromagnetic properties. The problems take a lot of computational time for analysis and cause the ill-posed condition. In this dissertation, the magnetic field is analyzed to develop the medical applications, using the extended distributed multi-pole (eDMP) method. The method utilizes the magnetic dipole moments to solve not only nonlinearity but also interactions and improve ill-posed condition. Based on the modeling method, the magnetic field can be controlled. Then the control method contributes to construct the magnetic field which enhance the performance of the applications. The methods are illustrated in two applications with experiments: a navigation sensor for an intubation tube and magnetic induction tomography (MIT). The navigation sensor for a tube is proposed to prevent a potential danger of perforation during tube intubation. A trajectory of the tube is reconstructed, based on the magnetic induction. The eDMP method is used to modeling the system and the optimal design is found, considering the practical usage. A MIT is a medical imaging device mapping conductivity of target objects. It shows inferior performance due to low signal-to-noise ratio and ill-posed condition. The eDMP method is applied to analyze the magnetic field of the MIT system and implement the system to reconstruct an image. The various materials with different conductivities are applied and their properties, such as the shape and conductivity, are characterized. Eventually, it is expected that the MIT system makes image of the biological cell and could be developed as the medical device.clos