Broadband refractive index sensor based on localized surface plasmon for highly sensitive detection of fluid pressure

Localized surface plasmon resonance (LSPR) in gold (Au) nanoparticles is the research hotspot in various fields, due to its high chemical and physical stability, ease of preparation and multiple optical properties. However, the anisotropic response to polarized light of LSPR has been rarely studied. Here, we report optical refractive index sensors based on the polarization sensitive response of LSPR in gold nanoparticles, and its application in the highly sensitive detection of fluid species and hydraulic pressure. The polarization-sensitive absorption characteristics of the interfacial nanoparticles rendering it different absorption properties for TM and TE mode waves under the condition of total reflection, which is also strongly affected by the refractive index of medium n2 in contact with it. On this basis, the refractive index sensor based on LSPR in gold nanoparticles is successfully realized. In addition, the refractive index sensor features broadband response (from 200 to 1000 nm) in a wide range of incident angle δ (from −10° to 25°), exhibiting great application potential in various scenarios. To evaluate the practical applicability of the proposed sensor, we constructed an optical refractive index sensing system that can distinguish between liquid species and accurately detect hydraulic pressure in real time.