Biomimetic pattern transfer

Biological systems routinely use phenols to construct complex materials with diverse functions. Typically, these phenolic materials are generated using oxidative enzymes to initiate a cascade of uncatalyzed reactions. We mimic these processes to micro-pattern films of aminopolysaccharide chitosan. Specifically, we microfabric silicon wafers to have gold patterns, cast a chitosan film onto the patterned wafers, and commence pattern transfer by polarizing the underlying gold surfaces to electro-chemically initiate the phenol reaction cascade. The electrochemically initiated reactions lead to modification of the chitosan film's chemistry, structure, and fluorescence. Further, electrochemically initiated modification of the chitosan film is localized to the interfacial region between the film and the anode, with resolution in the lateral direction of at least 20 mum. These results demonstrate that electrochemical pattern transfer provides a promising new method for micropatterning flexible films.