Applied Nanophotonics, Liquid Crystals and Biomedical Optics

Surface-enhanced fluorescence from porous, metallic sculptured thin films (STFs) was demonstrated for sensing of bacteria in water. Enhancement factors larger than 15 were observed using STFs made of silver, aluminum, gold, and copper with respect to their dense film counterparts. The STFs used are assemblies of tilted, shaped, parallel nanowires prepared with several variants of the oblique-angle-deposition technique. Comparison between the different films indicates that the enhancement factor is higher when the tilt is either small (<30 deg) or large (>80 deg); thus, the enhancement is higher when only a single resonance in the nanowires is excited.