Design of a Gas Sensor Transducer Circuitry With Calibration Ability for CO2 Concentration Detection

In this paper, a gas sensor and the proposed calibration chip are presented. For this paper, a commercially available MG811 CO₂ gas sensor is used. The output of the CO₂ gas sensor was inputted to the proposed chip, and the output signal of the chip is a pulse stream with its frequency corresponding to gas concentration. All functions of the CO₂ gas sensor and the proposed chip have been validated experimentally. After calibration, the concentration range of 426-1359 ppm corresponded to the output frequency range of 285-242 kHz. The measured maximum frequency error was 1.3%.