Fig. 1. Schematic view of PID sensing principle

Fig. 2. System hardware ciucuit diagram. (a) Weak current detection module and UV lamp drive module circuit diagram, (b) system block view of the whole circuit

Fig. 3. External package view of PID. (a) External package structure view of the PID, (b) external package physical view of the PID

Fig. 4. Measurement system of PID. (a) Architecture view of the PID measurement system, (b) physical view of the PID measurement system)

Fig. 5. Curve diagram and fitting diagram of the experimental output voltage. (a) Curve diagram of the values measured for seven times, (b) curve diagram of the average output point and the curve diagram by linear fit

Fig. 6. Experimental results of repeatability. (a) Measurement curve of repeatability, (b) concentration curve of reverse-acting gas