Integrated flexible parylene-based inductor with magnetic core for wireless power transmission system

Abstract

In this paper, flexible parylene-based MEMS inductors were designed, fabricated and analysed. A magnetic core was added in the centre of spiral coil in order to further enhance the performance of the inductor. FeNi alloy was chosen as the magnetic material due to its relatively high permeability. Parylene was used as substrate and insulation material due to its good bio-compatibility and flexibility. The performance of inductors was simulated in Ansoft HFSS. When the core radius increased from 800 μm to 1200 μm, the inductance was increased by 167% and the quality factor was increased by 20%. The inductors were fabricated using standard IC compatible MEMS fabrication process. Copper coils and magnetic cores were fabricated by electrodeposition technique. We also tested the performance of our fabricated inductors. When adding the magnetic core, the inductance was improved by 125% (from 44 nH to 100 nH) and the peak quality factor was improved by 18% (from 4.62 to 5.45). When the core radius increased from 800 μm to 1200 μm, the inductance was improved by 67% (from 173 nH to 289 nH) and the peak quality factor was improved by 83% (from 1.20 to 2.19). Finally, the fabricated inductors were tested in our experimental system. The minimum of transmission attenuation was –32 dB at 29 MHz.