Fig. 1. Working principle diagram of the fiber grating sensor

Fig. 2. Neck pulse monitoring device. (a) Schematic; (b) Bridge strain amplification structure; (c) Force analysis

Fig. 3. Pulse wave signal feature division

Fig. 4. Simulation results of neck monitoring device. (a) Sensing unit; (b) Force transfer structure

Fig. 5. Force calibration of neck monitoring device. (a) Calibration test bench; (b) Calibration of sensing unit; (c) Calibration experimental data analysis

Fig. 6. Temperature control experiment. (a) Experimental platform; (b) Experimental data

Fig. 7. Aging test. (a) Temperature aging data. (b) Force aging data

Fig. 8. Experimental data of signal attenuation

Fig. 9. Experimental platform of neck pulse monitoring device

Fig. 10. Monitoring data. (a) Volunteer 1 sit; (b) Volunteer 1 lies in supine position; (c) Volunteer 2 sit; (d) Volunteer 2 lies in supine position

Fig. 11. First full cycle of resting, exercise, and vigorous exercise state. (a) Volunteer 1 sit; (b) Volunteer 1 lies in supine position; (c) Volunteer 2 sit; (d) Volunteer 2 lies in supine position

Fig. 12. Frequency comparison of resting, exercise, and vigorous exercise states. (a) Volunteer 1 sit; (b) Volunteer 1 lies in supine position; (c) Volunteer 2 sit; (d) Volunteer 2 lies in supine position

Fig. 13. Correlation analysis of resting, exercise, and vigorous exercise state in each cycle. (a) Volunteer 1 sit; (b) Volunteer 1 lies in supine position; (c) Volunteer 2 sit; (d) Volunteer 2 lies in supine position

Fig. 14. Random forest error and decision tree number analysis of resting, exercise and vigorous exercise states. (a) Volunteer 1 sit;(b) Volunteer 1 lies in supine position; (c) Volunteer 2 sit; (d) Volunteer 2 lies in supine position