Smart control of chemical MOX gas sensors

The objective of this work is to present different control loops designed for improving the time response of metal-oxide gas sensors. This type of sensors generally present slow responses and in some cases, drift. Focusing on voltage actuation on the chemical layer, we discover an asymmetry of resistivity of the sensing layer as a function of the applied bias polarity. This phenomenon may be linked to sensor drift as well as to a built-in voltage in the layer. Different control loops have been designed to keep constant this asymmetric behaviour during the operation of the sensor. Experiments will be presented showing how the sensor operates under the proposed controls and how it responds to changes in the concentration of the gases to be measured.