Magnetic nanoparticle ink for RF integrated inductor applications

For the first time, a magnetic ink containing permalloy nanoparticles coated with a polyelectrolyte shell is presented for miniaturization of radio frequency (RF) integrated inductors. Coating permalloy particles with an electrolyte polymer provides particle separation which minimizes eddy current losses. Coated particles are incorporated into a viscous ink to enable precise deposition. This magnetic ink is integrated with a single-turn planar inductor. Measurements show a 40% inductance enhancement at GHz frequencies, a peak quality factor of 7.1, and a self-resonant frequency of 4.84 GHz. When compared with recent literature, this method shows promise for reducing the size of RF passives.