Smart control of chemical gas sensors for the reduction of their time response

The objective of this paper is to show the first results obtained with a gas sensor made of Au-functionalized WO3 nanoneedles working under a closed-loop control designed to reduce its time response. The average temperature applied to the sensor is modulated to keep constant the average surface potential of the sensing nanostructures. This is done by periodically monitoring the resistivity of the sensing layer and generating temperature waveforms that enforce the condition: constant resistivity of the sensing layer at a reference temperature. Changes induced by the target gases must be compensated by changes in the average temperature being applied to the sensing layer. This signal, the average temperature applied to the sensor, is the new sensor output.