Patterning with Magnetic Materials at the Micron Scale

This paper demonstrates the use of microcontact printing (μCP) and capillary filling (CF) to pattern the deposition of iron oxides on a surface with feature sizes of microns. Selective wetting of both self-assembled monolayers (SAMs) of alkanethiolates on gold and alkylsiloxanes on Si/SiO2 formed by microcontact printing limited the deposition of the iron oxides to the hydrophilic areas on the surfaces; thereby, the chemical functionality of the hydrophilic SAM had only a minor influence on the wetting behavior and the deposition. The iron oxides were deposited either as magnetite particles from colloidal solution, by precipitation of the oxide from previously deposited drops of water containing an iron(III) salt, or by ferrite plating. The size of the metal oxide patterns was limited to the size of the areas that could be patterned using μCP. Capillary filling using a colloidal solution of magnetite could also be used to fabricate continuous, interconnected structures of magnetite. The magnetic properties of the deposited iron oxides were characterized by magnetic force measurement (MFM) and by measurement of the magnetization. The magnetite particles deposited in these experiments showed superparamagnetic behavior; they were too small individually to support a permanent magnetization.