Behavior of MOX CO sensors during thermal transients

The low-power TGS2442 metal oxide (MOX) sensor is normally used with a pulsed heating excitation (i.e. a 14 ms-wide pulse of 5 V every second), and its resistance value is measured 2 ms before each heating pulse, with a 1s sampling period. This sensor is equipped with a charcoal filter in order to reduce the humidity influence on sensor operations. In this work the authors explore the possibility to use the sensor without the chemical filter, exploiting the sensor behavior in a very short time interval around the heating pulse. On the basis of both a theoretical study and an experimental data analysis, the authors propose a new CO detection technique with some benefits with respect to the standard technique suggested by the manufactures such as: independence from sensor calibration and reduced sensitivity to environmental conditions (temperature, humidity).