Ag and Au/DNQ-novolac nanocomposites patternable by ultraviolet lithography: a fast route to plasmonic sensor microfabrication

In this work we report on a method to synthesize Ag-Au nanoparticles/polymer nanocomposite patterns by UV lithography. The photoresists are based on DNQ-novolac as the polymer matrix, and Ag(I) and Au(III) salts as the nanoparticle precursors. After UV lithography, silver and gold nanoparticles are in situ synthesized inside the polymer patterns during a post bake. The resulting structured nanocomposite shows a characteristic absorbance spectrum related to the plasmon frequency of the synthesized noble metal NPs. This method represents a fast, simple and low-cost approach to the formation of extended polymer patterns with embedded silver or gold NPs. Moreover, it is a mechanism to position nanometric particles with micrometric resolution, which represents a useful tool for nanoscience. Furthermore, even with the polymeric cover, NPs plasmon resonance is affected by the binding of some organic molecules. This concept has been proven with 2-mercaptoethanol molecules, which demonstrates the feasibility of localized surface plasmon resonance chemo/biosensors by using the proposed technology.