Development of a simple CO2 sensor based on the thermal conductivity detection by a thermopile

A simple and effective thermal conductivity based CO2 gas sensor has been successfully developed. The CO2 sensor consists of a modified IR thermopile sensor without an IR window. The thermopile is heated by the AC current that is applied through the output terminals of the device, which in turn leads to a temperature gradient generating a DC output voltage. The gas exposed to the thermopile simultaneously cool down the thermopile. Thus, the thermopile can simultaneously serve as a heater and temperature sensor. The built-in sensors possess low production costs, low power consumption and are easily manufactured. From the conducted experiments, the sensor can work well, and the results can be validated with the established theory, as evidenced by the RMS error of 0.787. The measurement results are also in a good agreement with the model predictions Mason and Saxena for the thermal conductivity of gas mixtures.