In sensing applications, SPRs are employed to detect changes in the local refractive index near the nanoparticle surface. For instance, in a biosensor, the binding of target molecules to a functionalized nanoparticle surface can cause a shift in the resonance frequency. This shift can be monitored using spectroscopic techniques, providing a highly sensitive method for detecting low concentrations of analytes. The enhanced sensitivity is due to the strong local electromagnetic field generated by the SPR, which amplifies the interaction between the light and the analyte.
