Fig. 1. Optical transport characteristics of the FBG

Fig. 2. Thumb's fingerstall model

Fig. 3. Schematic diagram of the FBG force under pressure at different positions

Fig. 4. Constraint and force of the thumb touch pressure sensing unit

Fig. 5. Schematic diagram of the FBG strain simulation of the thumb sensing unit

Fig. 6. Variations of strain with stress at different positions

Fig. 7. Variations of simulated wavelength with stress at different positions

Fig. 8. Touch and pressure sensing experimental device

Fig. 9. Center wavelengths at different positions of the touch experiment

Fig. 10. Center wavelength change over time at 10 HA

Fig. 11. The central wavelength changes with the depth of touch pressure

Fig. 12. Data of central wavelength under different hardness touch pressure（six experiments）