We experimentally demonstrate the possibility to implement an optical bio-sensing platform based on the shift of the plasmonic band edge of a 2D-periodic metal grating. Several 2D arrangements of square gold patches on a silicon substrate were fabricated using electron beam lithography and then optically characterized in reflection. We show that the presence of a small quantity of analyte, i.e. isopropyl alcohol, deposited on the sensor surface causes a dramatic red shift of the plasmonic band edge associated with the leaky surface mode of the grating/analyte interface, reaching sensitivity values of ~650nm/RIU. At the same time, dark field microscopy measurements show that the spectral shift of the plasmonic band edge may also be detected by observing a change in the color of the diffracted field. Calculations of both the spectral shift and the diffracted spectra variations match the experimental results very well, providing an efficient mean for the design of sensing platforms based on color observation.© (2012) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Experimental demonstration of plasmonic-grating-assisted optical biosensor
DE VITTORIO, Massimo;
2012-01-01
Abstract
We experimentally demonstrate the possibility to implement an optical bio-sensing platform based on the shift of the plasmonic band edge of a 2D-periodic metal grating. Several 2D arrangements of square gold patches on a silicon substrate were fabricated using electron beam lithography and then optically characterized in reflection. We show that the presence of a small quantity of analyte, i.e. isopropyl alcohol, deposited on the sensor surface causes a dramatic red shift of the plasmonic band edge associated with the leaky surface mode of the grating/analyte interface, reaching sensitivity values of ~650nm/RIU. At the same time, dark field microscopy measurements show that the spectral shift of the plasmonic band edge may also be detected by observing a change in the color of the diffracted field. Calculations of both the spectral shift and the diffracted spectra variations match the experimental results very well, providing an efficient mean for the design of sensing platforms based on color observation.© (2012) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
