High-resolution magnetic patterning for printed electronics applications

Abstract

The unprecedented magnetic printing technology was developed to prepare conductive patterns which have a line width below 10um. Firstly, superparamagentic magnetite nanoparticles were synthesized by coprecipitation method, then the patterns consisting of the nanoparticles were fabricated on the plastic substrates using a magnetic mask, and finally conductive metal patterns were formed by using the nanoparticle patterns as a resist. Direct patterning of conductive material was also investigated. In chapter 2, superparamagnetic magnetite nanoparticles were prepared by coprecipitation method from aqueous Fe3+ and Fe2+ ion solution in basic condition. The size of Fe3O4 nanoparticles was easily con-trolled from 3 to 11.5 nm by varying the amount of citric acid (stabilizer). The effect of citric acid can be ex-plained by the adsorption of citrate ions on the magnetite nuclei, which inhibits the growth of the nuclei. XRD patterns show that the crystal structure of the prepared iron oxide nanoparticles is magnetite. The magnetic properties (M-H curve) of magnetite nanoparticles were investigated by vibrating sample magnetometer (VSM). As the size of magnetite nanoparticles increased from 3 to 11.5 nm, the saturation magnetization value also increased from 36 to 68 emu/g. All samples show superparamagnetic M - H curve in which the both remnant magnetization (Mr) and coercivity (Hc) were zero. An in situ self-polymerization method was developed to synthesize Fe3O4@PDA nanoparticles with well-defined core/shell nanostructures. The size of the core/shell product can be controlled by varying the ratio of dopamine monomer to the magnetite nanoparticles. The average thickness of the PDA shell was tunable from 4 to 40 nm by changing the ratio from 3.6 to 28.7. TEM data revealed that PDA shell steadily grew on the particles upto 8 hrs, but the increase rate of thickness became slower with time. In chapter 3, various patterns composed of magnetite nanoparticles were fabricated ...