UCLA

Magnetic devices - components that generate, manipulate, or detect magnetic fields - are used in a variety of applications ranging from medical imaging to information transfer and sensing. The persisting motivation to miniaturize electronic devices drives a need to more effectively manipulate magnetic fields in the millimeter scale. In this dissertation, two areas are presented where miniaturization technology has been applied to create new or improved capability in the area of milliscale magnetics. For the first application, a radio frequency (RF) surface coil with a dimension that is comparable to the area of interest can maximize the signal-to-noise ratio (SNR) in Magnetic Resonance Imaging (MRI) application, allowing for higher quality images than available existing tools. This work demonstrates a miniature flexible coil that can be inserted into the body for high SNR pituitary gland MR imaging. It presents the spatial distributions of the image SNR of the 26-mm coil in both numerical simulation and agar gel phantom experiments. Compared to the commercial head coil, the miniature coil achieved up to a 19-fold SNR improvement within the region of interest, and the simulation matched the phantom experiment within an error of 1.1% � 0.8%. Additionally, the coil performance was characterized with cadaver heads MRI scan using a 20-mm coil. A maximum of 16-fold and an average of 5-fold SNR improvement within the pituitary gland compared to the commercial head coil was obtained. The feasibility of using the miniature flexible coil for high-SNR pituitary MR imaging has been demonstrated, showing the potential for improved detection and characterization of pituitary gland microadenoma.In the second application, a novel way to shield the magnetic field of a single chip on a multi-chip-module is presented. This approach uses individual millimeter-size magnetic shield on each chip to reduce the chip-to-chip coupling effect of the circuits or influence on signal currents from local magnetic fields. Magnetic through silicon vias (mTSVs) were developed to help achieve the desired level of magnetic shielding. The microscale multilayer shields provided high efficiency shielding around arbitrary shapes and enabled fabrication of chip-scale shielding. This work focuses on the design and fabrication of the proposed magnetic shielding.