Topological insulator overlayer to enhance the sensitivity and detection limit of surface plasmon resonance sensor

Surface plasmon resonance (SPR) sensors have been applied in a wide range of applications for real-time and label-free detection. In this article, by covering the topological insulators nanosheets on the surface of the noble metal (Au), the sensitivity of the SPR sensor is greatly enhanced because of the strong interaction of light with Au-bismuth selenide (Bi2Se3) heterostructure. It is shown that the sensitivity of proposed SPR sensors depends on the concentration of Bi2Se3 solution or the thickness of the coated Bi2Se3 film. The optimised sensitivity (2929.1 nm/RIU) and figure of merit (33.45 RIU-1) have been obtained after three times drop-casting, and the enhancement sensitivity of proposed sensors is up to 51.97% compared to the traditional Au-SPR sensors. Meanwhile, the reflection spectrum is simulated by using the method of effective refractive index, and the reason for the increase of sensitivity is analysed theoretically. For researching the application of modified SPR sensor, heavy metal detection is employed to detect in the last part. Our proposed SPR sensors have potential applications in heavy metal detections and biosensing.