May 2, 2013
Short- and long-range SPP waveguides detect xylene
Researchers at Padua University in Italy have developed nanostructured plasmonic sensors fabricated as sinusoidal surface plasmon metallic gratings, embedded in a functional and porous hybrid sol-gel material – phenyl-bridged polysilsesquioxane. The metal layer is in contact with the environment through the sol-gel film, which operates as a sensing element and changes its dielectric properties upon interaction with aromatic hydrocarbons.
The combination of sensitivity, transparency and patternability offered by phenyl-bridged polysilsesquioxanes provides numerous possibilities for the fabrication of innovative optical sensors using straightforward processes.
The system, which is reported in the journal Nanotechnology, is composed of a thin metal slab waveguide in which the surface plasmon polaritons (SPPs) at the two metal-dielectric interfaces superpose. This results in two physical coupled modes: the long-range SPPs (LRSPPs) and the short-range SPPs (SRSPPs).
The sensor performance was tested against the detection of 30 ppm xylene by monitoring the influence of the target gas on the SPPs modes. A reversible red-shift of the reflectance dips of both LR and SRSPP resonances was observed and correlated to the interaction with the analyte. An enhancement in sensitivity associated with the rotation of the grating grooves with respect to the scattering plane was verified within experimental errors.
Additional details can be found in the journal Nanotechnology.
About the author
Laura Brigo is a postdoc in the Industrial Engineering Department at Padua University, under the supervision of Prof. Giovanna Brusatin. One of her main current research interests deals with the engineering of functional organic-inorganic hybrid sol-gel and nanocomposite systems for optical applications, and in particular the realization of plasmonic devices for detecting gaseous and ionic species with high sensitivity, through refractometric detection and surface enhanced Raman spectroscopy. Another field of research, tightly connected to the previous area, concerns the development of innovative functional resist materials for direct patterning using a number of micro and nanofabrication techniques: UV, X-ray and electron beam lithography, nano imprint lithography and soft lithography. Her research was performed in the framework of the PLATFORMS strategic project “PLAsmonic nano-Textured materials and architectures FOR enhanced Molecular Sensing”, funded by Padua University and coordinated by Prof. Massimo Guglielmi.