Fig. 1. Schematic diagram of the sensor structure

Fig. 2. Schematic diagram of reflection spectrum of the sensor

Fig. 3. Schematic diagram of the cascading grating implanted into silicone

Fig. 4. Diagram of the measurement system

Fig. 5. Photo of pulse diagnosis

Fig. 6. Pulse waveforms of healthy male young and elderly subjects

Fig. 7. Pulse waveforms of the same healthy male subjects at 8 am and 8 pm