1：Experimental Design and Method Selection:

The sensor uses a reflective structure with gold film to excite SPR, Cu-nanoparticles/carbon nanotubes composite film for nitrate sensing, and polydimethylsiloxane (PDMS) for temperature sensing. The dual-wavelength matrix method is employed for simultaneous measurement.

2：Sample Selection and Data Sources:

Nitrate solutions with concentrations from 2.5 × 10^{-6} to 1 × 10^{-3} M are used, and temperature is varied from 35°C to 57°C.

3：5 × 10^{-6} to 1 × 10^{-3} M are used, and temperature is varied from 35°C to 57°C. List of Experimental Equipment and Materials:

3. List of Experimental Equipment and Materials: Halogen light source (OSPEC LS-3000), Y-type fiber (Ocean Optics, BIF125-VIS-NIR), ocean spectrometer (Ocean Optics, USB2000+), ion sputtering apparatus (SAINT JS-1600), gold film, Cu-nanoparticles/carbon nanotubes composite, PDMS, chitosan, and other chemicals.

4：Experimental Procedures and Operational Workflow:

The sensing probe is fabricated by welding SMF and MMF, coating with gold film using ion sputtering, coating with Cu-NPs/CNT composite via dip coating, and coating half with PDMS. Light from the source is transmitted to the probe, reflected back to the spectrometer for spectrum analysis.

5：Data Analysis Methods:

Wavelength shifts of resonance dips are monitored, and sensitivities are calculated. A dual-wavelength matrix is used to decouple nitrate concentration and temperature effects.