Fig. 1. Effects of the changes in the refractive index of the grating surface on the LPFG resonance peak

Fig. 2. Antigen-antibody reaction curve

Fig. 3. Schematic of the nanofilm-modified LPFG biosensor

Fig. 4. Fabrication of the sensitive film. (a) Surface modified with sulfuric acid; (b) surface modified with APTES; (c) surface modified with glutaric dialdehyde; (d) immobilization of the identifying biomolecules

Fig. 5. Microscopic images. (a) Grating area before the experiment; (b) nanofilm-modified LPFG biosensing area after the immunoassay

Fig. 6. Effects of the pre-chemical treatments on the resonance peak of LPFG

Fig. 7. Effects of the immunoassay on the resonance peak of LPFG at Λ=445 μm. (a) Concentration of rabbit IgG with 0.0025-0.0075 mg·mL-1; (b) concentration of rabbit IgG with 0.0075-0.0300 mg·mL-1

Fig. 8. Peak loss of LPFG at Λ=445 μm with different rabbit IgG concentrations

Fig. 9. Peak loss of LPFG with different rabbit IgG concentrations. (a) Λ = 460 μm; (b) Λ = 500 μm