Fig. 1. Schematic of SPR sensor enhanced by two-dimensional Ti₃C₂Tx MXene nanosheet

Fig. 2. For the BAK1 prism/35 nm silver film/Ti₃C₂T_x MXene/monolayer graphene hybrid configuration, the calculated sensing performance by changing the number of Ti₃C₂T_x MXene layers when the excitation wavelength is 632.8 nm and the sensing medium is deionized water with the refractive index of 1.333. (a) Reflectivity; (b) phase

Fig. 3. SPR phase and reflectivity curves generated by the coupling BAK1 prism/35 nm silver film/3-layer Ti₃C₂T_x MXene/monolayer graphene when the excitation wavelength is 632.8 nm, and the sensing medium is deionized water with the refractive index of 1.333

Fig. 4. For the coupling BAK1 prism/silver film/Ti₃C₂T_x MXene/monolayer graphene SPR configuration, sensing performance changed with thicknesses of silver film and number of Ti₃C₂T_x MXene layers at Δn_bio=0.0012 RIU when the excitation wavelength is 632.8 nm. (a) Phase difference; (b) angle deflection

Fig. 5. Curves of phase difference changed with refractive index of medium by varying different thicknesses of silver film in the coupling BAK1 prism/silver film/Ti₃C₂T_x MXene/monolayer graphene SPR configuration when the excitation wavelength is 632.8 nm. (a) 30 nm; (b) 35 nm; (c) 40 nm; (d) 45 nm; (e) 50 nm; (f) 55 nm

Fig. 6. Simulated results at the sensing interface between Ti₃C₂T_x MXene and graphene. (a) Distribution of electric field intensity; (b) evanescent decay curve of electric field

Fig. 7. Comparison of the SPR sensing performances for different structures when the excitation wavelength is 632.8 nm

Table 1. Refractive indexes of SF11, BAF10, BAK1, BK7, gold film, and silver film

Table 2. Results of optimized SPR sensing performance