A surface plasmon resonance biosensor based on gold nanoparticle array

Using the finite-difference time-domain (FDTD) method, optical properties are investigated for a sensor comprising a two-dimensional array of gold cubes placed on quartz pillars on a quartz substrate. Background condition is analyzed for an approximate ideal collective resonance. It is found that the resonance intensity is mainly determined by the quartz etch depth, and the spectra valley position depends mainly on the lattice period. Thickness of the gold film affects the wavelength of the transmission spectra slightly, which gives a low processing tolerance requirement for fabrication. Sensitivity of the biosensor is also discussed, spectral sensitivity as high as 596.7 nm/refractive index unit (RIU) is obtained in the visible light region, making it an excellent candidate for liquid detection.