A combination of lithography and electrochemistry can be used to pattern arrays of free-standing metallic nanowires
One of the most important considerations in the synthesis of nanosized materials is the ability to control both their size and shape. Moreover, in order to make working devices from these very small components they must be assembled into ordered arrangements.
Now, John Wiley and co-workers1 at the University of New Orleans and Louisiana State University in the USA have used a combination of two well-known techniques to produce patterned arrays of either silver, gold or nickel nanowires. By using a standard photolithographic procedure, a particular pattern — as defined by the photo-mask — can be created on top of a porous alumina template, thereby sealing off the pores it covers. The surface is then coated with a thin layer of silver or gold, which serves as an electrode for the electrochemical deposition of metal — from the other side — into the pores that were not initially sealed. A sodium hydroxide wash removes the alumina template, leaving behind a pattern of free-standing metallic nanowires.
A wide range of patterns can be generated using different masks, and individual nanowire dimensions can be controlled by varying the pore size of the template and the duration of the deposition process.
Li, F. et al. J. Am. Chem. Soc. (2006). 10.1021/ja0647856