Fig. 1. Hardware topology diagram of concentration measurement system

Fig. 2. Physical images of collection devices and sensors

Fig. 3. Structure diagram of photoelectric sensor

Fig. 4. Structure diagram of isolation reflector

Fig. 5. Measurement principle diagram of photoelectric sensor

Fig. 6. Schematic diagram of AC and DC amplification circuits

Fig. 7. Structure diagram of collection box

Fig. 8. Calibration flume

Fig. 9. Concentration-voltage relationship curves of 1^#～10^# sensors

Fig. 10. Simple experimental setup

Fig. 11. Sensors layout and effect diagram of concentration field