Sensitive detection of nanoparticles using metallic nanoslit arrays

Abstract

The detection sensitivity of small nanoparticles was studied using surface plasmons in a metallic nanoslit array. When 13nm gold nanoparticles were immobilized on the array, the resonant wavelength and intensity of surface plasmons are substantially changed. Spectroscopic measurements and finite-difference time-domain calculations identified that the surface plasmons in the slit gap had a greater sensitivity than those on the outside surface. Using a nanoslit array with a gap of 50nm, a thickness of 150nm, and a period of 600nm, the authors achieved a detection sensitivity of 1nanoparticle∕μm2 for a 0.2% intensity change.