Surface plasmon-based sensing

Abstract

This report presents a simplified model on the characterization of surface plasmon resonance (SPR)-based refractive index sensor using spectral detection technique. The theoretical simulation uses a multi-layer Kretschmann configuration model which consists of prism, gold layer, linker layer, sample layer and buffer. Wavelength dependence of the materials has been included in the model. A better understanding of the effects from different parameters is essential for the sensor design and system optimization. The effects of the gold film, the linker and the sample are analyzed systematically by numerical simulation. The results show that for spectral detection, the optimal range of gold thickness is 40 nm to 50 nm and thickness for linker layer should be small within 1 nm to 20 nm. Thermal effect is also considered in the model by including the change of material thickness and dielectric constant due to thermal expansion. The results show that change in temperature will cause linear shift of resonance spectral. Based on the simplified model, the theoretical refractive index sensitivity of spectral detection can reach up to 1.5×10-5 refractive index unit (RIU) which agrees well with the experimental results.