A novel doublet-based surface plasmon resonance biosensor via a digital Gaussian filter method

Abstract

In this paper, a digital Gaussian filter coupled surface plasmon resonance (SPR) sensor with a doublet was proposed to enhance the sensing performance of conventional SPR sensor. The shift of central angle calculated from doublet was employed instead of the shift of resonance angle obtained from SPR curve. Expected angle and FWHM (full width at half maximum) are two parameters for the post-processing Gaussian model. The refractive index (RI) sensitivity has a symmetry relationship with expected angle and the reversed maximum sensitivity is usually larger than that of forward maximum. The reversed maximum sensitivity increases first and then decreases when increasing FWHM from 0.2 to 20 deg. Further, a dynamic and adjustable Gaussian model was employed to satisfy the large sensing range need. The RI sensitivity as high as 254.21 deg/RIU was obtained, which is nearly 2-fold higher than that of traditional gold-based SPR sensor, that is 131.58 deg/RIU. And thus, the RI resolution was calculated to be 7.16 × 10−6 RIU based on three-fold standard deviation theory. The LOD for rabbit IgG as low as 9.58 ng/mL was achieved and it is nearly 3-fold lower than that of traditional gold-based SPR biosensor, that is 30.64 ng/mL.