Resonant noble metal nanoparticles with dimensions of a few tens of nanometers and sustaining Localized Surface Plasmon (LSP) modes have been recently proposed as good candidates for increasing both integration and sensitivity compared to conventional extended thin metal films. Very recently several groups have reported results of sensing with a single nano-particle.
The study we present contains two main parts. First, using randomly distributed colloidal gold spheres, we demonstrate the ability of LSP sensors for monitoring quantitatively and without the use of any label, the binding between small organic molecules and antibodies with real-life applications. In a second part, the Fourier Modal Method (FMM) is used to model controlled geometries of particles that allow for optimizing the sensor properties. In particular, we show that the electromagnetic coupling within a periodic 2D particle array can be optimized to increase the field localization and thus the sensitivity of the sensor.
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