This paper presents a surface plasmon resonance (SPR) sensor based on an Au/TiO2 metal-dielectric interface. The proposed sensor is designed to detect refractive index variations within the range of 1.32 to 1.36. The performance of the sensor is evaluated in terms of confinement loss and sensitivity. For a refractive index change of 0.01, the maximum confinement loss decreases from 4200 dB/cm to 3800 dB/cm, with resonance wavelengths shifting from 0.85 μ m to 0.87 μ m, respectively. This variation in confinement loss demonstrates the sensor’s capability to detect changes in external refractive indices. Furthermore, the sensor exhibits a high sensitivity of 4000 nm / RIU, measured as the shift in resonance wavelength of 40 nm with respect to the refractive index change of 0.01 RIU. These results highlight the potential application of the proposed sensor in detecting external biological samples.