Ricerc@Sapienza

Silver nanoparticles capped with 3-mercapto-1propanesulfonic acid sodium salt (AgNPs-3MPS), able to interact with Ni2+or Co2+, have been prepared to detect these heavy metal ions in water. This system works as an optical sensor and it is based on the change of the intensity and shape of optical absorption peak due to the surface plasmon resonance (SPR) when the AgNPs-3MPS are in presence of metals ions in a water solution. We obtain a specific sensitivity to Ni2+and Co2+up to 500 ppb (part per billion).

This paper presents the analysis and development of an evanescent waveguide sensor system, based on a hydrogenated amorphous silicon (a-Si:H) photodiode and a double ion-exchanged waveguide diffused in a borosilicate BK7 glass substrate. The a-Si:H sensor is a p-doped/intrinsic/n-doped diode, with a metal top electrode and an indium tin oxide (ITO) transparent bottom contact. Simulations on the confinement of a monochromatic light in a channel waveguide and its coupling into a thin-film photodetector were performed using COMSOL Multiphysics.