Iron Oxide Nanoparticle‐Based Magnetic Ink Development for Fully Printed Tunable Radio‐Frequency Devices

Abstract The field of printed electronics is still in its infancy and most of the reported work is based on commercially available nanoparticle‐based metallic inks. Although fully printed devices that employ dielectric/semiconductor inks have recently been reported, there is a dearth of functional inks that can demonstrate controllable devices. The lack of availability of functional inks is a barrier to the widespread use of fully printed devices. For radio‐frequency electronics, magnetic materials have many uses in reconfigurable components but rely on expensive and rigid ferrite materials. A suitable magnetic ink can facilitate the realization of fully printed, magnetically controlled, tunable devices. This report presents the development of an iron oxide nanoparticle‐based magnetic ink. First, a tunable inductor is fully printed using iron oxide nanoparticle‐based magnetic ink. Furthermore, iron oxide nanoparticles are functionalized with oleic acid to make them compatible with a UV‐curable SU8 solution. Functionalized iron oxide nanoparticles are successfully embedded in the SU8 matrix to make a magnetic substrate. The as‐fabricated substrate is characterized for its magnetostatic and microwave properties. A frequency tunable printed patch antenna is demonstrated using the magnetic and in‐house silver‐organo‐complex inks. This is a step toward low‐cost, fully printed, controllable electronic components.