Fig. 1. Schematic diagram of parallel sensor structure

Fig. 2. Production process of PI cavity and PDMS cavity

Fig. 3. Schematic diagram and microscopic views of sensor testing device. (a) Experimental test equipment diagram; (b) microscopic image of FPI₁ sensor; (c) microscopic image of FPI₂ sensor

Fig. 4. Reflection spectra. (a) Reflectance spectra of individual FPI₁ and FPI₂; (b) reflection spectrum of parallel structure

Fig. 5. Stability test results. (a) Characteristic spectral changes; (b) shift of wavelength position

Fig. 6. RH response characteristics. (a) FPI₁ humidity response characteristics; (b) fitting of FPI₁ wavelength displacement curve; (c) curves of envelope varying with RH; (d) fitting of envelope displacement curve

Fig. 7. Temperature response characteristics. (a) FPI₂ temperature response characteristics; (b) fitting of FPI₂ wavelength displacement curve; (c) envelope varying with temperature; (d) fitting of envelope displacement curve

Fig. 8. Trends of interference spectra of FPI₁ and FPI₂ varying with temperature and humidity. (a) FPI₂ humidity response characteristics; (b) fitting of FPI₂ wavelength displacement curve; (c) FPI₁ temperature response characteristics; (d) fitting of FPI₁ wavelength displacement curve