High-Sensitivity SPR Temperature Sensor Based on Ag/NiO Nanoflowers

This work presents a high-sensitivity surface plasmon resonance (SPR) temperature sensor based on a BK7 prism coated with silver film and NiO nanoflowers. NiO nanoflowers were synthesized via hydrothermal method and deposited onto the Ag film using a drop-casting technique (3 cycles optimized). The resulting BK7/Ag/NiO nanoflowers structure significantly enhances refractive index (RI) sensitivity. Finite element method (FEM) simulations and experimental measurements confirmed the sensor's performance. The Ag/NiO nanoflowers sensor achieved a remarkable RI sensitivity of 4138.34 nm/RIU, representing a 63.83% improvement over a bare Ag film sensor. Leveraging this enhanced sensitivity and the strong thermo-optic coefficient of silicone oil, a temperature sensor (BK7/Ag/NiO nanoflowers /silicone oil) was developed. It exhibited an excellent temperature sensitivity of -1.61 nm/°C over the range of 25 °C to 75 °C, with a low detection limit of 0.075 °C. The sensor also demonstrated good repeatability and stability, making it a promising candidate for highly sensitive temperature sensing applications.