Sensitivity and figure-of-merit enhancements of liquid-prism SPR sensor in the angular interrogation

Abstract We use a glass slide covered with metal film as the sensing chip and the liquid over the glass slide as the prism (also called liquid prism) to excite the surface plasmon between the metal and the sample in a Kretschmann–Raether surface plasmon resonance (SPR) configuration. In this work, we demonstrate theoretically and experimentally that the lower refractive index of the liquid prism can enhance the angular sensitivity and the figure of merit (FOM) of SPR sensor. Meanwhile, the adjustment of the refractive index of the liquid prism is easier than the solid prism, and the more suitable refractive index of the liquid prism can be obtained for the specific sample to enhance the sensitivity and the FOM. The proposed liquid prism SPR configuration provided a new chemical and biological SPR sensing application with highly sensitive and high FOM.