We experimentally investigate the local refractive index sensitivity of plasmonic gold nanodisks by applying small polymer dots to selected disk sites by means of two-step lithography. Measured sensitivity profiles obtained from tracking the polymer-induced spectral shift of the plasmon modes are in excellent agreement with numerical simulation of both spectral sensitivity and the electric near field of the nanodisks. Based on the nanodisk sensitivity profile we tailor a sensitive and spatially uniform plasmonic sensor by capping the disk with a dielectric layer, thus restricting analyte access to the disk rim.

The excitation of surface plasmon polaritons by focusing a laser beam onto a hole pair in a thin gold film is studied both experimentally and theoretically. By means of leakage radiation microscopy we quantitatively measure the light-plasmon coupling efficiency as a function of the hole distance. We find a modulation of the coupling efficiency as a function of hole distance that strongly depends on the polarization direction of the incident light, in agreement with theoretical simulations.

Understanding of the phase transition dynamics of substrate tethered brushes of thermoresponsive poly(N-isopropylacrylamide) (pNIPAM) is important for their application as, e.g., cell substrates with spatially selective cell affinity or drug delivery systems. But characterization of the brushes phase transition time is hampered by the low amount of involved pNIPAM. Here, by the simultaneous use of time resolved nanoplasmonic heating and sensing, we are able to measure a transition time of 160±20 μs for a 30 nm thick substrate tethered brush. The plasmon-induced temperature jump can be quantitatively deduced from the measured data. Nanoplasmonic platforms as applied here could serve as local and fast probes for a variety of dynamic processes in stimuli responsive molecules or polymers.