Fig. 1. Schematic diagram of principle of dual-wavelength differential detection method

Fig. 2. Overall design of infrared CO₂ sensor. (a) Schematic diagram; (b) cross-sectional view

Fig. 3. Light source drive circuit

Fig. 4. Signal processing circuit

Fig. 5. Flowchart of software operation

Fig. 6. Sensor calibration experimental platform. (a) Platform structure; (b) picture

Fig. 7. Calibration data of standard gas at different temperatures and concentrations. (a) Relationship between peak-to-peak value difference and concentration at different temperatures; (b) relationship between peak-to-peak value difference and temperature at different concentrations

Fig. 8. Relationship between peak-to-peak value difference after temperature compensation and gas concentration