Fig. 1. Schematic diagram of knee bend detection system

Fig. 2. (a) Schematic diagram of sensor package; (b) Schematic diagram of sensor is encapsulated and fixed on the knee joint

Fig. 3. Schematic diagram of the knee joint bending detection

Fig. 4. (a) Schematic diagram of the MZI-BDB sensor design; (b) Microscope image of the cross-sections of the eccentric core fiber

Fig. 5. Schematic diagram of bending simulation of MZI-BDB sensor

Fig. 6. Schematic diagram of MZI-BDB sensor characteristic detection device

Fig. 7. (a) Wavelength shifting variation of the resonance wave under different curvatures for bending directions of 0°, 90°, and 180°; (b) Wavelength shifting variation of the resonance wave under different temperatures

Fig. 8. Wavelength shift of the resonance wave of the MZI-BDB sensor. (a) Left knee joint bending; (b) Right knee joint bending

Fig. 9. Wavelength shift of the resonant Valley in the MZI-BDB sensor when the subjects are walking. (a) Right knee joint bending; (b) Left knee joint bending

Fig. 10. Installation structure diagram of photoelectric encoder

Fig. 11. Angle obtained through the optical-electricity encoders during walking: (a) Right knee joint; (b) Left knee joint