Optimal geometry for plasmonic sensing with non-interacting Au nanodisk arrays

Combining finite elements method electrodynamic simulations and cost-effective and scalablenanofabrication techniques, we carried out a systematic investigation and optimization of the sensingproperties of non- interacting gold nanodisk arrays. Such plasmonic nanoarchitectures offer a veryeffective platform for fast and simple, label-free, optical bio- and chemical-sensing. We varied their maingeometrical parameters (diameter and height) to monitor the plasmonic resonance position and tofindthe configurations that maximize the sensitivity to small layers of an analyte (local sensitivity) or to thevariation of the refractive index of an embedding medium (bulk sensitivity). The spectral position of theplasmonic resonance can be tuned over a wide range from the visible to the near-IR region (500–1300nm) and state-of-the-art performances can be obtained using the optimized nanodisks; we obtainedlocal and bulk sensitivities of S0=11.9 RIU^-11and Sbulk=662 nm/RIU, respectively. Moreover, theresults of the simulations are compared with the performances of experimentally synthesized non-interacting Au nanodisk arrays fabricated by combining sparse colloidal lithography and hollow masklithography, with the parameters obtained by the sensitivity numerical optimization. An excellentagreement between the experimental and the simulated results is demonstrated, confirming that theoptimization performed with the simulations is directly applicable to nanosensors realized with cost-effective methods, due to the quite large stability basin around the maximum sensitivities.