This study presents a strain sensor based on plasmonic Fano resonances. The investigated system consists of U-shaped aluminum nanowires that are fabricated at wafer scale with hot embossing and oblique metal evaporation. The proposed process is compatible with roll-to-roll manufacturing. The observed Fano resonance is very sensitive to the spacing between the wires and responds to strain with a spectral shift as well as attenuation of the resonance amplitude. This relation between nanoscopic displacement and optical properties is investigated with scanning electron microscopy and numerical simulations. Finally, a clearly visible color change from purple to green is achieved through optimization of the structural parameters, which enables colorimetric or even visual sensing and hence remote read-out for example using a camera.
Advanced Optical Materials, vol. 4 (5), pp. 715-721, May 2016.