title: Identification of the optimal spectral region for plasmonic and nanoplasmonic sensing.
abstract: We present a theoretical and experimental study involving the sensing characteristics of wavelength-interrogated plasmonic sensors based on surface plasmon polaritons (SPP) in planar gold films and on localized surface plasmon resonances (LSPR) of single gold nanorods. The tunability of both sensing platforms allowed us to analyze their bulk and surface sensing characteristics as a function of the plasmon resonance position. We demonstrate that a general figure of merit (FOM), which is equivalent in wavelength and energy scales, can be employed to mutually compare both sensing schemes. Most interestingly, this FOM has revealed a spectral region for which the surface sensitivity performance of both sensor types is optimized, which we attribute to the intrinsic dielectric properties of plasmonic materials. Additionally, in good agreement with theoretical predictions, we experimentally demonstrate that, although the SPP sensor offers a much better bulk sensitivity, the LSPR sensor shows an approximately 15% better performance for surface sensitivity measurements when its FOM is optimized. However, optimization of the substrate refractive index and the accessibility of the relevant molecules to the nanoparticles can lead to a total 3-fold improvement of the FOM in LSPR sensors.
authors: Nanobiosensors and Bioanalytical Applications Group, Research Centre in Nanoscience and Nanotechnology (CIN2) CSIC-ICN & CIBER-BBN, 08193 Bellaterra, Barcelona, Spain.
authors: Marinus A
authors: MA
authors: Otte
authors: Borja
authors: B
authors: Sepúlveda
authors: Weihai
authors: W
authors: Ni
authors: Jorge Pérez
authors: JP
authors: Juste
authors: Luis M
authors: LM
authors: Liz-Marzán
authors: Laura M
authors: LM
authors: Lechuga
mesh_terms: D017097:Electric Impedance; D005898:Glass / Q000737:chemistry; D006046:Gold / Q000737:chemistry; D008962:Models, Theoretical; D036103:Nanotechnology; D043942:Nanotubes / Q000737:chemistry; D015203:Reproducibility of Results; D020349:Surface Plasmon Resonance / Q000379:methods*
chemical_list: D006046:Gold