Patterned silver island paths as high-contrast optical sensing platforms

Abstract

Abstract Well-defined paths assembled of silver islands were fabricated by combining photolithography with wet-chemical synthesis. The islands feature lateral sizes of the order of 100\xa0nm, and similar heights, thus promoting localized plasmon resonance. Wavelength-dependent fluorescence imaging as well as time-resolved fluorescence of photoactive proteins deposited on such a substrate confirms enhancement of the fluorescence due to coupling with the plasmon resonance. The coupling leads to strong contrast in the optical response, which enables direct imaging of photoactive protein emission. Importantly, the contrast can be further improved by covering the silver island paths with graphene and taking advantage of a very efficient energy transfer.