A Low-resistance and Low-parasitic Capacitance Micro Coil for MRI Fabricated by Selective Deposition on 3D Stepped Helical Structures

Abstract

This paper reports a bicone-shaped micro coil that has a low resistance and a low parasitic capacitance for magnetic resonance imaging (MRI). The micro coil was fabricated by vacuum evaporation and electroplating of copper (Cu) onto a stepped helical structure developed by a three-dimensional (3D) printer. Because the stepped helical structure was fixed on a rotary-tilted stage, Cu was evaporated only on the coil wiring part of the helical structure. Unlike for the folding method, a micro coil developed by vacuum evaporation could be fabricated even if there were lines that overlapped between the coil wirings. Furthermore, the resistance of the coil could be decreased by electroplating, and by increasing the linewidth of the coil wiring that was fabricated by the 3D printer. By using the fabricated bicone-shaped coil, high signal-to-noise ratio (SNR) MRI images could be obtained. In conclusion, a higher SNR MRI image can be obtained by increasing the linewidth and decreasing the resistance.