Abstract: A toroidal microinductor comprises a nanocomposite magnetic core employing superparamagnetic nanoparticles covalently cross-linked in an epoxy network. The core material eliminates energy loss mechanisms in existing inductor core materials, providing a path towards realizing low form factor devices. As an example, both a 2 ?H output and a 500 nH input microinductors comprising superparamagnetic iron nanoparticles were modeled for a high-performance buck converter. Both modeled inductors had 50 wire turns, less than 1 cm3 form factors, less than 1 ?AC resistance and quality factors, Q's, of 27 at 1 MHz. In addition, the output microinductor had an average output power of 7 W and power density of 3.9 kW/in3.