Fig. 1. Schematic diagram of TFBG-SPR sensing system structure

Fig. 2. Schematic diagram of mercury ion detection principle based on magnetic nanoparticles and aptamer base pairing

Fig. 3. Signal response of TFBG-SPR mercury ion sensor based on aptamer and magnetic nanoparticles. (a) SPR spectrum response of plasmonic optical fiber (concentration of mercury ion is 10 μmol/L); (b) relative intensity change of modes 1-6 during mercury ion detection; (c) total intensity change of modes 1-6 after 25 min reaction

Fig. 4. Detection of different concentrations of TFBG-SPR mercury ions using mercury ion sensor based on aptamer and magnetic nanoparticles

Fig. 5. Selective detection of TFBG-SPR mercury ion sensor based on aptamer and magnetic nanoparticles

Fig. 6. Reproducibility test of TFBG-SPR mercury ion sensor based on aptamer and magnetic nanoparticles. (a) SEM image of magnetic nanoparticles on sensing surface before reaction with mercury ions; (b) SEM image of magnetic nanoparticles on sensing surface after reaction with 1 μmol/L mercury ions; (c) SEM image of magnetic nanoparticles on sensing surface after reaction with iodine ions; (d) SEM image of magnetic nanoparticles on sensing surface after secondary detection of mercury ions at the same concentration; (e) total intensity change of TFBG-SPR cladding mode