Fig. 1. Schematic diagram of micro-nano fiber optic hydrogen ion concentration probe sensing structure

Fig. 2. Structural changes in the main chain of polyaniline bound to hydrogen ions.

Fig. 3. Diagram of experimental setup for hydrogen ion concentration sensing

Fig. 4. Microscope photo comparison before and after lamination

Fig. 5. Spectrum superimposition of micronaire fiber optic hydrogen ion probe

Fig. 6. Linear fitting of micro-nanofiber hydrogen ion concentration probe wavelength with increasing hydrogen ion concentration

Fig. 7. Linear fit of fiber optic probe wavelength with hydrogen ion concentration for different polyaniline film thickness

Fig. 8. Fluctuation of the wave valley of a micro-optic hydrogen ion concentration probe with the refractive index of sodium chloride solutions

Fig. 9. Fluctuation of the wave valley of a micro-optic hydrogen ion concentration probe with the refractive index of sucrose solutions

Fig. 10. Response-recovery curve of micro-nanofiber hydrogen ion concentration probe

Fig. 11. Linear fitting of micro-nanofiber hydrogen ion concentration probe wavelength with hydrogen ion concentration