Fig. 1. Schematic diagram of the front-end circuit of the visual pulse detection system

Fig. 2. Performance test results of photodetector. (a) XRD data of PbS quantum dots; (b) TEM of PbS quantum dots, the illustration is a histogram showing the distribution of diameter sizes of PbS quantum dots, (c) SEM of PbS photodetectors, (d) SEM-EDS of PbS photodetector

Fig. 3. (a) Current-voltage (I-V) diagram of PbS quantum dot photodetector at different optical power densities; (b) current-time (I-T) diagram of PbS quantum dot photodetector at different optical power densities when bias is −3 V; (c) response time of PbS quantum dot photodetector at 9390 μW·cm⁻² light intensity, (d) responsivity curve and specific detection rate curve of PbS photodetector at different optical power densities

Fig. 4. (a) The physical image of the visual pulse detection system based on the PbS quantum dot photodetector; (b) the display diagram of the electronic display screen during the actual measurement of the system

Fig. 5. Pulse changes of the same test subject at different motor states

Fig. 6. (a) Pulse change plot of different testers at the same exercise state; (b) pulse change plot of the same tester at different test times

Fig. 7. Voltage diagram of the same tester tested by different test systems