Detection of low ppm carbon monoxide with charge ordered LuFe2O4 gas sensor - A novel sensing mechanism

The field of solid state gas sensing is dominated by metal oxide semiconductors, whose modality of detecting volatiles is primarily governed by the chemisorption kinetics of the surface dwelling oxygen adatoms. The performance of these sensors is thus related to the quality of the sensor surface and is influenced by constraints like surface deterioration, foreign contamination and humidity absorption. In order to mitigate these limitations, charge ordered spin frustrated lutetium ferrite has been investigated as a sensing material for detection of low concentrations of carbon monoxide. The lutetium ferrite based sensors have a unique sensing mechanism where its already collapsed charge order is partially restored in presence of carbon monoxide, allowing it to mitigate the constraints pertinent to the quality of the sensor surface. The partial restoration of charge order is recognized by a significant nonlinear increase in the sensor impedance, when the toxic gas is dispensed in its ambience. Normally, the phenomenon of charge order collapsing and restoration in multiferroics is produced by external impetus in form of optical, thermal or magnetic stimuli. The scope of producing a similar effect through modulation of external ambience has immense possibility not only in the field of multiferroics but also in gas sensing where the dilemmas associated with surface detection might be mitigated through this approach.